CASE REPORT
Cervical spinal intradural arachnoid cysts in related, young pugs C. Rohdin*,†, H. T. Nyman‡, P. Wohlsein§ and K. Hultin Jäderlund¶ *Department of Clinical Sciences, University Animal Hospital, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden †Albano Small Animal Hospital, Rinkebyvägen 21, 182 36 Danderyd, Sweden ‡Regional Small Animal Hospital, Bagarmossen, Ljusnevägen 17, 128 48 Bagarmossen, Sweden §Department of Pathology, University of Veterinary Medicine, Buenteweg 17, D-30559 Hannover, Germany ¶Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway
Seven related young pugs were diagnosed with cervical spinal intradural arachnoid cysts by magnetic resonance imaging (n=6) and myelography (n=1). All dogs were presented with skin abrasions on their thoracic limbs and non-painful neurological deficits, indicating a C1-T2 myelopathy. In all six dogs examined by magnetic resonance imaging not only the spinal arachnoid cyst but also a concomitant, most likely secondary, syringohydromyelia was confirmed. Pedigree analysis suggested a genetic predisposition for spinal arachnoid cysts in this family of pugs. Generalised proprioceptive deficits more pronounced in the thoracic limbs suggesting a focal cervical spinal cord lesion, with concomitant skin abrasions on the dorsal aspect of the thoracic limbs in a young pug, should alert veterinarians to the possibility of cervical spinal arachnoid cysts. Journal of Small Animal Practice (2014) 55, 229–234 DOI: 10.1111/jsap.12167 Accepted: 22 October 2013; Published online: 27 December 2013
INTRODUCTION Intra-spinal, extraneural, cystic processes are space-occupying lesions that may have different histogenetic origin, topography and clinical relevance. In dogs, arachnoidal, discal, epidermoid, ganglion and synovial cysts have been described (Summers et al. 1995, Perez et al. 2000, Dickinson et al. 2001, Konar et al. 2008). Intracranially located arachnoidal cysts have also been described in humans and dogs (Vernau et al. 1997, 2002, Daneyemez et al. 1999, Duque et al. 2005). Spinal arachnoid cysts are considered rare causes of spinal cord compression in both dogs and humans (Skeen et al. 2003, Wang et al. 2003) and have previously been described as “arachnoidmeningeal-leptomeningeal cysts”, “leptomeningeal cavitations”, or “pseudocysts” (Parker et al. 1983, Dyce et al. 1991, McKee & Renwick 1994, Ness 1998, Frykman 1999, Galloway et al. 1999, Webb 1999, Hashizume 2000, Rylander et al. 2002, Gnirs et al. 2003, Skeen et al. 2003, Jurina & Grevel 2004, Goncalves et al. 2008, Itamoto 2010, Oxley & Pink 2012). As these structures generally do not compromise closed epithelial lined cavities the term “cyst” is a misnomer and should rather be referred to as a diverticulum (Parker et al. 1983, Gnirs et al. 2003). However, in analogy with a recent report the term “spinal intradural arachnoid cyst” (SIAC) will be used in this report to maintain Journal of Small Animal Practice
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consistency with the existing human and veterinary literature (Oxley & Pink 2012). The aetiology of SIACs in dogs is unclear (de Lahunta & Glass 2009b), although most are thought to develop secondary to congenital malformations of the arachnoid membrane (Parker et al. 1983, Bentley et al. 1991, McKee & Renwick 1994, Hardie et al. 1996, Ness 1998). In addition, cysts considered to have developed as a sequel to spinal cord trauma, intervertebral disc herniation, hemivertebrae, scoliosis, arachnoiditis and spinal dysraphism have been reported (Gage et al. 1968, Parker & Smith 1974, Dyce et al. 1991, Bagley et al. 1997, Galloway et al. 1999, Rylander et al. 2002, Gnirs et al. 2003). SIACs can occur at any level of the spinal cord but commonly are found in cranial cervical and caudal thoracic regions, which are areas of high spinal mobility (Gnirs et al. 2003, Skeen et al. 2003). The majority of large breed dogs with SIACs have cysts located in the cervical region while small breed dogs more commonly develop cysts in the thoracolumbar region (Table 1). Clinical signs of SIACs are consistent with a chronic progressing myelopathy with neurological deficits reflecting the localisation of the lesion. SIACs are rarely associated with signs of pain (Rylander et al. 2002, Skeen et al. 2003).
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Table 1. Summary of previous published cases of SIACs Breed
No.
Age at presentation
Gender
Localisation
Japanese akita Beagle Bulldog Bull terrier Chesapeake Bay retriever Chihuahua Chow chow Corgi Dachshund Dobermann Flat-coated retriever Great Dane Labrador retriever Mixed breed Newfoundland Pekingese Poodle, miniature Pug
1 1 1 1 1
18 m 4y 2y Unknown 10 m
M F F F M
C TL T T C
1 1 1 2 1 1 4 3 1 1 1 1 8
Rhodesian ridgeback Rottweiler
3 29
Schipperke Siberian husky Shar Pei Shih-tzu Staffordshire Terrier cross Toy poodle Weimaraner Welsh Corgi West Highland white terrier Wolfhound Unknown Total
2 1 1 5 2 1 2 1 1 3
11 m 3y 10 y 5 to 12 y 8m 10 m 6 m to 10 y 7 m to 11 y 9y 6y 15 m 2y 9 m to 10 y (3 unknown) 10 to 18 m 7 m to 8 y (14 unknown) 14 m to 2·5 y 8y 2y 18 w to 7·5 y 22 m to 3 y 4m 3 to 6 y 10 y 3y 4 m to 9 y
M M F 1 F, 1 M M Unknown 1 F, 3 M 3F M M F F 1 F, 4 M (3 unknown) 1 F, 2 M 3 F, 12 M, (14 unknown) 2M M F 2 F, 3 M 1 F, 1 M Unknown 2F F F 1 F, 2 M
T T L 1 T, 1 TL C C 3 C, 1 TL 2 C, 1 L T C T T 2 C, 2 T, 1 TL, (3 unknown) 3C 13 C, 1 T, 1 TL, (14 unknown) 1 C, 2 T TL T 3 C, 2 T 1 C, 1 TL T 2C C T 2 T, 1 L
3y 25 18 w to 11 y 25 unknown
M 26 25 F, 39 M, 26 unknown
C 24 37 C, 20 T, 7 TL, 3 L, 24 unknown
1 7 90
References Hashizume (2000) Parker (1974) Chen (2005) Galloway (1999) Skeen (2003) Skeen (2003) Dyce (1991) Galloway (1999) Rylander (2002), Skeen (2003) Dyce (1991) Itamoto (2010) Galloway (1999), Chen (2005), Skeen (2003) Skeen (2003) Skeen (2003) Galloway (1999) Parker (1983) Rylander (2002) Rylander (2002),Gnirs (2003), Skeen (2003), Chen (2005), Foss (2009), Oxley (2012) Dyce (1991), Galloway (1999) Frykman (1999), Rylander (2002), Gnirs (2003) Skeen (2003), Jurina (2004) Frykman (1999) Perez (2000) Hardie (1996) Ness (1998), Webb (1999), Chen (2005) Galloway (1999), Goncalves (2008) Dyce (1991) Parker (1983), Skeen (2003) Gage (1968) Skeen (2003) McKee (1994), Skeen (2003) Galloway (1999) Rylander (2002), Gnirs (2003)
m month, y year, M male, F female, C cervical, TL thoracolumbar, L lumbar
A dilation of the central canal is referred to as hydromyelia and a cavitation of the spinal cord parenchyma as syringomyelia (de Lahunta & Glass 2009a). The term syringohydromyelia is frequently used when histopathology has not been performed, confirming the ependymal lining to be either intact or disrupted. Syringohydromyelia is thought to result from an obstruction of the normal cerebrospinal fluid pulsation. In dogs, it has been described in association with Chiari-like malformation, neoplasia, spinal dysraphism, vertebral malformation, intervertebral disc herniation (McGrath 1965, Furneaux et al. 1973, Chauvet et al. 1996, Rylander et al. 2002, Da Costa et al. 2004, Jung et al. 2006) and in conjunction with arachnoid cysts (Parker et al. 1983, Dyce et al. 1991, Galloway et al. 1999, Skeen et al. 2003, Jurina & Grevel 2004, Foss et al. 2009, Oxley & Pink 2012). Hereditary congenital SIACs have never been specifically described in dogs, although cases in two young Shih-tzu littermates (Ness 1998) and two adult Schipperkes descending from the same bitch (Frykman 1999) have been reported. Heredity has also been suggested in Rottweilers, a breed frequently reported with SIACs (Rylander et al. 2002, Gnirs et al. 2003). 230
This case series presents clinical, neurological and imaging findings in seven young pugs with SIACs with a pedigree analysis suggesting a genetic predisposition.
CASE HISTORIES The medical records of seven pug dogs with SIACs were reviewed. Four dogs were examined by the first author, a board-certified neurologist, between 2008 and 2012. The other three related pugs were examined by other veterinarians during the same time period. All pugs were fawn and five were male. At three to four months of age the owners first noticed that the dogs would scuff their front feet, causing skin abrasions. The clinical signs progressed to a point where the dogs could not be walked on hard surfaces without wearing protection booties. The neurological signs progressed with age to the point of the dogs becoming incoordinated and falling to the side. At initial examination, all pugs were alert and responsive. The four pugs examined by the first author presented with a varying degree of proprioceptive ataxia and showed tetraparesis more
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FIG 1. T1W and T2W sagital (A and B) MRI images of the cervical spine of a seven-month-old male Pug. A focal T1 hypointense and T2 hyperintense lesion (arrow) dorsal to the spinal cord and confluent with the subarachnoid space is present from cranial C2 to mid body C3. The adjacent spinal cord is compressed by the dorsally located SIAC. Within the spinal cord parenchyma a hyperintensity is present in the T2W images from mid C3 to cranial C6. (C) Transverse T2W MRI image of the dog in (A) and (B), at the level of C2-C3 showing the hyperintense dilation of the dorsal subarachnoid space compressing the spinal cord. (D) Transverse T2W MRI image of the dog in (A) and (B), at the level of C3-C4 showing the dilation of the central canal and suspected fluid accumulation within the spinal cord, indicating a syringohydromyelia
pronounced in the thoracic limbs. There were skin abrasions on the dorsum of the thoracic limb paws. Cranial nerves were unremarkable. Postural reactions were delayed in all four limbs and spinal reflexes were decreased in the thoracic limbs in two dogs and considered normal in the remaining two pugs. No signs of pain were elicited on palpation and manipulation of the cervical portion of the vertebral column. Neurological deficits indicated a C1-T2 myelopathy. Five pugs underwent MRI examination, using a 1.5 Tesla magnet. An MRI was performed on an additional dog using a low-field MRI. Sagittal T1W and T2W images were obtained of the entire cervical spine, including the caudal fossa of the skull. Transverse T1W and T2W (and in one dog FLAIR) images were obtained over the lesions in the cranial cervical spine in four pugs. In two dogs, sagittal T1W and T2W images were obtained of the entire brain and the cervical spine to C5. In relation to the spinal cord all dogs had a well-defined T1 (and FLAIR) hypointense and T2 hyperintense focal dilation (isointense to the cerebrospinal fluid (CSF) within the subarachnoid space) of the dorsal subarachnoid space located at or just to the side of midline over the disc space of C2-C3. This dilation was gradually enlarging from the mid to caudal portion of C2, creating a teardrop-shaped compression over the cranial portion of C3. These lesions were interpreted as SIACs (Fig 1). The C2-C3 disc had normal signal intensity in all dogs, but was bulging mildly in five of the dogs causing mild compression of the ventral subarachnoid space, this resulted in a flattened shape of the spinal cord over the C2-C3 Journal of Small Animal Practice
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disc in these pugs. The spinal cord was comparatively larger just caudal to the area of the SIAC and then tapered to the size seen in the remainder of the cervical spine. One dog, examined at 6·5 months of age, showed an intervertebral disc degeneration at C6-C7 with minimal protrusion and no signs of spinal cord compression. All dogs had varying degrees of dilation of the central canal caudal to the SIAC. These extended over a distance of approximately one half to three vertebrae in length. The more T2 hyperintense central canal was surrounded by a more ill-defined T2 hyperintensity. This ill-defined hyperintensity was mainly seen around the cranial aspect of the lesion and interpreted as oedema. None of the pugs showed pathology in the caudal fossa, specifically no Chiari-like malformation. One pug was referred to surgery for a cervical SIAC, previously diagnosed by an MRI. However, the MRI study was not available to the surgeons. Instead a myelogram performed preoperatively showed a tear drop-shaped enlargement of the dorsal subarachnoid space over C2-C3, which is consistent with an SIAC causing spinal cord compression. Three of the pugs underwent surgery, between six and seven months of age. A dorsal laminectomy and marsupialisation of the cyst were performed. All three dogs improved after surgery. However, one pug was euthanased within 1 month postoperatively because of neurological deterioration. A pathological examination was not performed. One pug, examined 6 months postoperatively, was diagnosed with mild neurological deficits including
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were related to each other. The most recent common ancestor was a male, born in 1991 (Fig 3).
DISCUSSION
FIG 2. Cervical spinal cord at C2 with distended arachnoidal space (asterisks), focal villous arachnoidal proliferation (arrow) and distortion of the dorsal funiculi (arrowheads), H&E. x40
mild generalised ataxia without scuffing, according to the owner the dogs neurological status has remained stable for more than a year. Another pug was euthanased 1 year postoperatively because of persistent non-progressive gait abnormalities. Pathology was not performed. Two conservatively treated pugs are still alive. At the time of this study they are 3·5 years and greater than 1 year of age. According to the owner the older pug is fully ambulatory, does not show any signs of pain but is unable to walk on hard surfaces without wearing protection devices. The younger pug is ambulatory, but unable to go for regular walks due to frequent falling. Two pugs were euthanased immediately after diagnosis, one at six months and the other at one year of age. The spinal cord of the six-month-old pug was fixed in formalin and sent for histopathological evaluation. Pathological findings In the cervical spine at the level of C2-3, a distended arachnoid space with a moderate villous proliferation of meningothelial cells of the arachnoidea, a focal mild infiltration of lymphocytes and macrophages was found (Fig 2). The dorsal funiculi appeared slightly compressed, a mild dilation of myelin sheaths with axonal swelling and infiltration of few myelinophages were observed. The ventro-lateral funiculi showed mild dilation with few myelinophages. In the ventral funiculi a severe dilation of myelin sheaths with axonal swelling, few myelinophages and mild gliosis were found. The central canal was moderately to severely dilated with focal rupture of the ependymal lining. This distention of the central canal was present even at the lumbar portion of the spinal cord. The histopathological findings were suggestive of an arachnoidal diverticulum with degenerative leucomyelopathy and hydromyelia. Pedigree analysis Pedigrees were obtained from the Swedish and Norwegian Kennel Club registry (www.skk.se, www.nkk.no). The pedigrees of the affected dogs were scrutinised and compared. Seven dogs 232
The uniform phenotype combined with the young age at onset of clinical signs and the relationship between affected dogs, suggest an inherited predisposition for cervical SIACs in these pugs. Although SIACs have been reported previously in pugs (Rylander et al. 2002, Gnirs et al. 2003, Skeen et al. 2003, Chen et al. 2005, Foss et al. 2009, Oxley & Pink 2012), to the authors’ knowledge, only one has been described at this young age (Rylander et al. 2002) and all but two had the SIAC in the thoracolumbar area. In the five pugs previously reported with SIACs, in which MRI was performed, concomitant syringohydromyelia was described in two (Foss et al. 2009, Oxley & Pink 2012) (Table 1). The initial mechanism for the formation of an SIAC is not completely understood and likely multifactorial. SIACs have been shown to develop secondary to some acquired conditions (Perret et al. 1962, Gage et al. 1968, Parker & Smith 1974, Fortuna et al. 1977, Dyce et al. 1991, Bagley et al. 1997, Galloway et al. 1999, Lee & Cho 2001, Rylander et al. 2002, Gnirs et al. 2003, Wang et al. 2003, Kahraman et al. 2008). However, SIACs in younger dogs have been described as representing congenital lesions (Gnirs et al. 2003, Skeen et al. 2003, Jurina & Grevel 2004). A congenital lesion is defined as existing at or before birth (Davis 1993). It is not possible to determine whether the affected pugs developed their SIACs early in life, or if the SIACs were actually present at birth. Considering the slowly progressive nature of the neurological signs from an SIAC, it is reasonable to assume that the development of the SIAC precedes the presence of signs observed by the owners. Subtle proprioceptive deficits in a young pug may also be considered signs of immaturity and thereby dismissed by the owners. By the time the dog shows skin abrasions the SIAC is likely to have been developing for many months and may therefore indicate a congenital lesion. However, a developmental aetiology in the reported pugs cannot be excluded. A common sire was found in the pedigree of the seven affected pugs, consistent with a genetic background of SIACs in this family. A genetic susceptibility to form SIACs in dogs, due to an overrepresentation of certain breeds, has previously been suggested (Ness 1998, Frykman 1999, Rylander et al. 2002, Jurina & Grevel 2004). However, evidence of heredity has been lacking as pedigree or genetic analysis has not been performed. An MRI examination of an additional, eighth, pug with tetraparesis and scuffing of the thoracic limbs showed an SIAC dorsal to C2-C3 and a massive cervical syringohydromyelia at the age of five months. This pug was, however, not included in the case series as its pedigree was unavailable. In contrast to the majority of affected small breed dogs having thoracolumbar SIACs the cysts were located cervically in all seven pugs in this report, this is consistent with the situation in Rottweilers were SIACs have been reported in the cervical area in 13 of 15 dogs (87%) (Frykman 1999, Skeen et al. 2003, Jurina & Grevel 2004). The overrepresentation of Rottweilers suggests
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FIG 3. Pedigree of the relationship among the seven pugs affected by spinal intradural arachnoid cysts, through their most recent common ancestor (arrow). Full litters are only depicted for litters containing affected dogs. Dogs with unknown status are labelled as unaffected
a genetic predisposition to developing SIACs. It has also been linked to the dog’s conformation, e.g. the size and weight of the head (Gnirs et al. 2003). The male predominance among affected pugs may be a coincidence because of the small number of dogs, although hormonal factors or sex-linked inheritance cannot be excluded. Five of the pugs also showed mild bulging of the disc at C2-C3 causing a compression of the ventral spinal subarachnoid space. Together with the dorsal bulging of the SIAC this caused a flattening of the spinal cord in this area, which is likely to interfere with the normal flow of CSF. It might be argued that, although normally hydrated, the bulging discs could be an early sign of disc protrusion, predisposing the pugs to develop SIACs (Galloway et al. 1999). On the MRI, one of the pugs showed a T2 hypointense intervertebral disc at C6-C7 with mild protrusion. The affected pugs started to show clinical signs at around four months of age when it would conventionally be considered unlikely for disc degeneration to be clinically relevant (Hansen 1952). SIACs (Gnirs et al. 2003, Skeen et al. 2003) and degenerated discs (Rohdin et al. 2010) are, irrespectively of one another, commonly found in areas of high mobility and may explain the presence of both SIACs and bulging discs in the same area. All six dogs undergoing MRI displayed dilation of the central canal caudal to the SIACs in the cervical spinal cord. The development of syringohydromyelia is suggested to be caused Journal of Small Animal Practice
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by alterations in CSF flow within the spinal subarachnoid space (Holly et al. 2006). Syringohydromyelia has been widely reported in dogs in association with Chiari-like malformation. However, none of the pugs in this report showed any of the MRI features characterising this disorder (Dewey et al. 2004). The incidence of concurrent syringohydromyelia and SIAC is not known because many of the previously reported dogs with SIACs were not examined by MRI which is necessary for the detection of syrinx formation in vivo. As a conclusion, pedigree analysis confirmed a relationship between the dogs affected by SIACs, suggesting a genetic predisposition for the disorder in this family of pugs. Signs of a focal cervical spinal cord lesion in a young pug should alert the clinician to the possibility of cervical, spinal arachnoid cysts. Conflict of interest None of the authors of this article has a financial or personal relationship with other people or organisations that could inappropriately influence or bias the content of the paper. References Bagley, R. S., Silver, G. M., Seguin, B., et al. (1997) Scoliosis and associated cystic spinal cord lesion in a dog. Journal of the American Veterinary Medical Association 211, 573-575 Bentley, J. F., Simpson, S. T. & Hathcock, J. T. (1991) Spinal arachnoid cyst in a dog. Journal of the American Animal Hospital Association 27, 549-551
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Chauvet, A. E., Darien, D. L. & Steinberg, G. H. (1996) What is your neurologic diagnosis? Spinal abnormalities and syringomyelia of the lumbar spinal cord. Journal of the American Veterinary Medical Association 208, 1387-1389 Chen, A. V., Bagley, R. S., West, C. L., et al. (2005) Fecal incontinence and spinal cord abnormalities in seven dogs. Journal of the American Veterinary Medical Association 227, 1945-1951 Da Costa, R. C., Parent, J. M., Poma, R., et al. (2004) Cervical syringohydromyelia secondary to a brainstem tumor in a dog. Journal of the American Veterinary Medical Association 225, 1061-1064 Daneyemez, M., Gezen, F., Akbörü, M., et al. (1999) Presentation and management of supratentorial and infratentorial arachnoid cysts. Review of 25 cases. Journal of Neurosurgical Sciences 43, 115-121 Davis, F. A. (1993) Taber´s Cyclopedic Medical Dictionary. 17th edn. Ed C. L. Thomas. F. A. Davis Company, Philadelphia, PA, USA. p435 de Lahunta, A. & Glass, E. (2009a) Development of the nervous system: malformation. In: Veterinary Neuroanatomy and Clinical Neurology 3rd edn. Eds A. de Lahunta and E. Glass. W. B. Saunders, St. Louis, MO, USA. p 47 de Lahunta, A. & Glass, E. (2009b) Lower motor neuron: General somatic efferent, cranial nerve. Veterinary Neuroanatomy and Clinical Neurology 3rd edn. Eds A. de Lahunta and E. Glass. W. B. Saunders, St. Louis, MO, USA. p263 Dewey, C. W., Berg, J. M., Stefanacci, J. D., et al. (2004) Caudal occipital malformation syndrome in dogs. Compendium 886-896 Dickinson, P. J., Sturges, B. K., Berry, W. L., et al. (2001) Extradural spinal synovial cysts in nine dogs. Journal of Small Animal Practice 42, 502-509 Duque, C., Parent, J., Brisson, B., et al. (2005) Intracranial arachnoid cysts: are they clinically significant? Journal of Veterinary Internal Medicine 19, 772-774 Dyce, J., Heritage, M. E., Houlton, J. E. F., et al. (1991) Canine spinal “arachnoid cysts”. Journal of Small Animal Practice 32, 433-437 Fortuna, A., La Torre, E. & Ciapetta, P. (1977) Arachnoid diverticula: a unitary approach to spinal cysts communicating with the subarachnoid space. Acta Neurochirurgica (Wien) 39, 259-268 Foss, K. D. & Berry, W. L. (2009) What is your neurological diagnosis? Spinal arachnoid cysts. Journal of American Veterinary Medical Association 234, 1009-1011 Frykman, O. F. (1999) Spinal arachnoid cyst in four dogs: diagnosis, surgical, treatment and follow-up results. Journal of Small Animal Practice 40, 544-549 Furneaux, R. W., Doige, C. E. & Kaye, M. M. (1973) Syringomyelia and spina bifida occulta in a Samoyed dog. The Canadian Veterinary Journal 14, 317-321 Galloway, A. M., Curtis, N. C., Sommerlad, S. F., et al. (1999) Correlative imaging in seven dogs and one cat with spinal arachnoid cysts. Veterinary Radiology & Ultrasound 40, 445-452 Gage, E. D., Hoerlein, B. F. & Bartels, J. E. (1968) Spinal cord compression resulting from a leptomeningeal cyst in the dog. Journal of the American Veterinary Medical Association 152, 1664-1670 Gnirs, K., Ruel, Y., Blot, S., et al. (2003) Spinal subarachnoid cysts in 13 dogs. Veterinary Radiology & Ultrasound 44, 402-408 Goncalves, R., Hammond, G. & Penderis, J. (2008) Imaging diagnosis: erroneous localization of spinal arachnoid cyst. Veterinary Radiology & Ultrasound 49, 460-463 Hansen, H. J. (1952) A pathologic-anatomical study on disc degeneration in dog. Acta Orthopaedica Scandinavica. Supplementum (Suppl 11) 1-117 Hardie, R. J., Linn, K. A. & Rendano, V. T. (1996) Spinal meningeal cyst in a dog: a case report and literature review. Journal of the American Animal Hospital Association 32, 477-480 Hashizume, C. T. (2000) Cervical spinal arachnoid cyst in a dog. The Canadian Veterinary Journal 41, 225-227
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Holly, L. T. & Batzdorf, U. (2006) Syringomyelia associated with intradural arachnoid cysts. Journal of Neurosurgery: Spine 5, 111-116 Itamoto, K. (2010) A case involving a dog with a cervical arachnoid cyst treated with marsupilization surgery. Journal of the Japan Veterinary Medical Association 63, 375-378 Jung, D. I., Park, C., Kang, B. T., et al. (2006) Acquired cervical syringomyelia secondary to a brainstem meningioma in a Maltese dog. The Journal of Veterinary Medical Science 68, 1235-1238 Jurina, K. & Grevel, V. (2004) Spinal arachnoid pseudocysts in 10 rottweilers. Journal of Small Animal Practice 45, 9-15 Kahraman, S., Anik, I., Gocmen, S., et al. (2008) Extradural giant multiloculated arachnoid cyst causing spinal cord compression in a child. The Journal of Spinal Cord Medicine 31, 306-308 Konar, M., Lang, J., Flühmann, G., et al. (2008) Ventral intraspinal cysts associated with the intervertebral disc: magnetic resonance imaging observations in seven dogs. Veterinary Surgery 37, 94-101 Lee, H. J. & Cho, D. Y. (2001) Symtomatic spinal intradural arachnoid cysts in the pediatric age group: description of three new cases and review of the literature. Pediatric Neurosurgery 35, 181-187 McGrath, J. T. (1965) Spinal dysraphism in the dog. With comments on syringomyelia. Pathologia Veterinaria 2 (Suppl), 1-36 McKee, W. M. & Renwick, P. W. (1994) Marsupialisation of an arachnoid cyst in a dog. Journal of Small Animal Practice 35, 108-111 Ness, M. G. (1998) Spinal arachnoid cysts in two Shih Tzu littermates. The Veterinary Record 142, 515-516 Oxley, W. & Pink, J. (2012) Amelioration of caudal thoracic syringohydromyelia following surgical management of an adjacent arachnoid cyst. Journal of Small Animal Practice 53, 67-72 Parker, A. J. & Smith, C. W. (1974) Meningeal cyst in a dog. Journal of the American Animal Hospital Association 10, 595-597 Parker, A. J., Adams, W. M. & Zachary, J. F. (1983) Spinal arachnoid cysts in the dog. Journal of the American Animal Hospital Association 19, 1001-1008 Perez, B., Rollan, E., Ramiro, F., et al. (2000) Intraspinal synovial cyst in a dog. Journal of the American Animal Hospital Association 36, 235-238 Perret, G., Green, D. & Keller, J. (1962) Diagnosis and treatment of intradural arachnoid cysts of the thoracic spine. Radiology 79, 287-290 Rohdin, C., Jeserevic, J., Viitmaa, R., et al. (2010) Prevalence of radiographic detectable intervertebral disc calcifications in Dachshunds surgically treated for disc extrusion, Acta Veterinaria Scandinavica 52, 24 Rylander, H., Lipsitz, D., Berry, W. L., et al. (2002) Retrospective analysis of spinal arachnoid cysts in 14 dogs. Journal of Veterinary Internal Medicine 16, 690-696 Skeen, T. M., Olby, N. J., Muñana, K. R., et al. (2003) Spinal arachnoid cysts in 17 dogs. Journal of the American Animal Hospital Association 39, 271-282 Summers, B. A., Cummings, J. F. & deLahunta, A. (1995) Tumors of the central nervous system. In: Veterinary Neuropathology. Eds B. A. Summers, J. F. Cummings and A. de Lahunta. Mosby-Year Book, St. Louis, MO, USA. p345 Vernau, K. M., Kortz, G. D., Koblik, P. D., et al. (1997) Magnetic resonance imaging and computed tomography characteristics of intracranial intra-arachnoid cysts in 6 dogs. Veterinary Radiology & Ultrasound 38, 171-176 Vernau, K. M., LeCouteur, R. A., Sturges, B. K., et al. (2002) Intracranial intraarachnoid cyst with intracystic hemorrhage in two dogs. Veterinary Radiology & Ultrasound 43, 449-54. Wang, M. Y., Levi, A. D. & Green, B. A. (2003) Intradural spinal arachnoid cysts in adults. Surgical Neurology 60, 49-56 Webb, A. A. (1999) Intradural spinal arachnoid cyst in a dog. The Canadian Veterinary Journal 40, 588-589
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Cervical spinal intradural arachnoid cysts in related, young pugs C. Rohdin*,†, H. T. Nyman‡, P. Wohlsein§ and K. Hultin Jäderlund¶ *Department of Clinical Sciences, University Animal Hospital, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden †Albano Small Animal Hospital, Rinkebyvägen 21, 182 36 Danderyd, Sweden ‡Regional Small Animal Hospital, Bagarmossen, Ljusnevägen 17, 128 48 Bagarmossen, Sweden §Department of Pathology, University of Veterinary Medicine, Buenteweg 17, D-30559 Hannover, Germany ¶Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway
Seven related young pugs were diagnosed with cervical spinal intradural arachnoid cysts by magnetic resonance imaging (n=6) and myelography (n=1). All dogs were presented with skin abrasions on their thoracic limbs and non-painful neurological deficits, indicating a C1-T2 myelopathy. In all six dogs examined by magnetic resonance imaging not only the spinal arachnoid cyst but also a concomitant, most likely secondary, syringohydromyelia was confirmed. Pedigree analysis suggested a genetic predisposition for spinal arachnoid cysts in this family of pugs. Generalised proprioceptive deficits more pronounced in the thoracic limbs suggesting a focal cervical spinal cord lesion, with concomitant skin abrasions on the dorsal aspect of the thoracic limbs in a young pug, should alert veterinarians to the possibility of cervical spinal arachnoid cysts. Journal of Small Animal Practice (2014) 55, 229–234 DOI: 10.1111/jsap.12167 Accepted: 22 October 2013; Published online: 27 December 2013
INTRODUCTION Intra-spinal, extraneural, cystic processes are space-occupying lesions that may have different histogenetic origin, topography and clinical relevance. In dogs, arachnoidal, discal, epidermoid, ganglion and synovial cysts have been described (Summers et al. 1995, Perez et al. 2000, Dickinson et al. 2001, Konar et al. 2008). Intracranially located arachnoidal cysts have also been described in humans and dogs (Vernau et al. 1997, 2002, Daneyemez et al. 1999, Duque et al. 2005). Spinal arachnoid cysts are considered rare causes of spinal cord compression in both dogs and humans (Skeen et al. 2003, Wang et al. 2003) and have previously been described as “arachnoidmeningeal-leptomeningeal cysts”, “leptomeningeal cavitations”, or “pseudocysts” (Parker et al. 1983, Dyce et al. 1991, McKee & Renwick 1994, Ness 1998, Frykman 1999, Galloway et al. 1999, Webb 1999, Hashizume 2000, Rylander et al. 2002, Gnirs et al. 2003, Skeen et al. 2003, Jurina & Grevel 2004, Goncalves et al. 2008, Itamoto 2010, Oxley & Pink 2012). As these structures generally do not compromise closed epithelial lined cavities the term “cyst” is a misnomer and should rather be referred to as a diverticulum (Parker et al. 1983, Gnirs et al. 2003). However, in analogy with a recent report the term “spinal intradural arachnoid cyst” (SIAC) will be used in this report to maintain Journal of Small Animal Practice
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consistency with the existing human and veterinary literature (Oxley & Pink 2012). The aetiology of SIACs in dogs is unclear (de Lahunta & Glass 2009b), although most are thought to develop secondary to congenital malformations of the arachnoid membrane (Parker et al. 1983, Bentley et al. 1991, McKee & Renwick 1994, Hardie et al. 1996, Ness 1998). In addition, cysts considered to have developed as a sequel to spinal cord trauma, intervertebral disc herniation, hemivertebrae, scoliosis, arachnoiditis and spinal dysraphism have been reported (Gage et al. 1968, Parker & Smith 1974, Dyce et al. 1991, Bagley et al. 1997, Galloway et al. 1999, Rylander et al. 2002, Gnirs et al. 2003). SIACs can occur at any level of the spinal cord but commonly are found in cranial cervical and caudal thoracic regions, which are areas of high spinal mobility (Gnirs et al. 2003, Skeen et al. 2003). The majority of large breed dogs with SIACs have cysts located in the cervical region while small breed dogs more commonly develop cysts in the thoracolumbar region (Table 1). Clinical signs of SIACs are consistent with a chronic progressing myelopathy with neurological deficits reflecting the localisation of the lesion. SIACs are rarely associated with signs of pain (Rylander et al. 2002, Skeen et al. 2003).
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Table 1. Summary of previous published cases of SIACs Breed
No.
Age at presentation
Gender
Localisation
Japanese akita Beagle Bulldog Bull terrier Chesapeake Bay retriever Chihuahua Chow chow Corgi Dachshund Dobermann Flat-coated retriever Great Dane Labrador retriever Mixed breed Newfoundland Pekingese Poodle, miniature Pug
1 1 1 1 1
18 m 4y 2y Unknown 10 m
M F F F M
C TL T T C
1 1 1 2 1 1 4 3 1 1 1 1 8
Rhodesian ridgeback Rottweiler
3 29
Schipperke Siberian husky Shar Pei Shih-tzu Staffordshire Terrier cross Toy poodle Weimaraner Welsh Corgi West Highland white terrier Wolfhound Unknown Total
2 1 1 5 2 1 2 1 1 3
11 m 3y 10 y 5 to 12 y 8m 10 m 6 m to 10 y 7 m to 11 y 9y 6y 15 m 2y 9 m to 10 y (3 unknown) 10 to 18 m 7 m to 8 y (14 unknown) 14 m to 2·5 y 8y 2y 18 w to 7·5 y 22 m to 3 y 4m 3 to 6 y 10 y 3y 4 m to 9 y
M M F 1 F, 1 M M Unknown 1 F, 3 M 3F M M F F 1 F, 4 M (3 unknown) 1 F, 2 M 3 F, 12 M, (14 unknown) 2M M F 2 F, 3 M 1 F, 1 M Unknown 2F F F 1 F, 2 M
T T L 1 T, 1 TL C C 3 C, 1 TL 2 C, 1 L T C T T 2 C, 2 T, 1 TL, (3 unknown) 3C 13 C, 1 T, 1 TL, (14 unknown) 1 C, 2 T TL T 3 C, 2 T 1 C, 1 TL T 2C C T 2 T, 1 L
3y 25 18 w to 11 y 25 unknown
M 26 25 F, 39 M, 26 unknown
C 24 37 C, 20 T, 7 TL, 3 L, 24 unknown
1 7 90
References Hashizume (2000) Parker (1974) Chen (2005) Galloway (1999) Skeen (2003) Skeen (2003) Dyce (1991) Galloway (1999) Rylander (2002), Skeen (2003) Dyce (1991) Itamoto (2010) Galloway (1999), Chen (2005), Skeen (2003) Skeen (2003) Skeen (2003) Galloway (1999) Parker (1983) Rylander (2002) Rylander (2002),Gnirs (2003), Skeen (2003), Chen (2005), Foss (2009), Oxley (2012) Dyce (1991), Galloway (1999) Frykman (1999), Rylander (2002), Gnirs (2003) Skeen (2003), Jurina (2004) Frykman (1999) Perez (2000) Hardie (1996) Ness (1998), Webb (1999), Chen (2005) Galloway (1999), Goncalves (2008) Dyce (1991) Parker (1983), Skeen (2003) Gage (1968) Skeen (2003) McKee (1994), Skeen (2003) Galloway (1999) Rylander (2002), Gnirs (2003)
m month, y year, M male, F female, C cervical, TL thoracolumbar, L lumbar
A dilation of the central canal is referred to as hydromyelia and a cavitation of the spinal cord parenchyma as syringomyelia (de Lahunta & Glass 2009a). The term syringohydromyelia is frequently used when histopathology has not been performed, confirming the ependymal lining to be either intact or disrupted. Syringohydromyelia is thought to result from an obstruction of the normal cerebrospinal fluid pulsation. In dogs, it has been described in association with Chiari-like malformation, neoplasia, spinal dysraphism, vertebral malformation, intervertebral disc herniation (McGrath 1965, Furneaux et al. 1973, Chauvet et al. 1996, Rylander et al. 2002, Da Costa et al. 2004, Jung et al. 2006) and in conjunction with arachnoid cysts (Parker et al. 1983, Dyce et al. 1991, Galloway et al. 1999, Skeen et al. 2003, Jurina & Grevel 2004, Foss et al. 2009, Oxley & Pink 2012). Hereditary congenital SIACs have never been specifically described in dogs, although cases in two young Shih-tzu littermates (Ness 1998) and two adult Schipperkes descending from the same bitch (Frykman 1999) have been reported. Heredity has also been suggested in Rottweilers, a breed frequently reported with SIACs (Rylander et al. 2002, Gnirs et al. 2003). 230
This case series presents clinical, neurological and imaging findings in seven young pugs with SIACs with a pedigree analysis suggesting a genetic predisposition.
CASE HISTORIES The medical records of seven pug dogs with SIACs were reviewed. Four dogs were examined by the first author, a board-certified neurologist, between 2008 and 2012. The other three related pugs were examined by other veterinarians during the same time period. All pugs were fawn and five were male. At three to four months of age the owners first noticed that the dogs would scuff their front feet, causing skin abrasions. The clinical signs progressed to a point where the dogs could not be walked on hard surfaces without wearing protection booties. The neurological signs progressed with age to the point of the dogs becoming incoordinated and falling to the side. At initial examination, all pugs were alert and responsive. The four pugs examined by the first author presented with a varying degree of proprioceptive ataxia and showed tetraparesis more
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FIG 1. T1W and T2W sagital (A and B) MRI images of the cervical spine of a seven-month-old male Pug. A focal T1 hypointense and T2 hyperintense lesion (arrow) dorsal to the spinal cord and confluent with the subarachnoid space is present from cranial C2 to mid body C3. The adjacent spinal cord is compressed by the dorsally located SIAC. Within the spinal cord parenchyma a hyperintensity is present in the T2W images from mid C3 to cranial C6. (C) Transverse T2W MRI image of the dog in (A) and (B), at the level of C2-C3 showing the hyperintense dilation of the dorsal subarachnoid space compressing the spinal cord. (D) Transverse T2W MRI image of the dog in (A) and (B), at the level of C3-C4 showing the dilation of the central canal and suspected fluid accumulation within the spinal cord, indicating a syringohydromyelia
pronounced in the thoracic limbs. There were skin abrasions on the dorsum of the thoracic limb paws. Cranial nerves were unremarkable. Postural reactions were delayed in all four limbs and spinal reflexes were decreased in the thoracic limbs in two dogs and considered normal in the remaining two pugs. No signs of pain were elicited on palpation and manipulation of the cervical portion of the vertebral column. Neurological deficits indicated a C1-T2 myelopathy. Five pugs underwent MRI examination, using a 1.5 Tesla magnet. An MRI was performed on an additional dog using a low-field MRI. Sagittal T1W and T2W images were obtained of the entire cervical spine, including the caudal fossa of the skull. Transverse T1W and T2W (and in one dog FLAIR) images were obtained over the lesions in the cranial cervical spine in four pugs. In two dogs, sagittal T1W and T2W images were obtained of the entire brain and the cervical spine to C5. In relation to the spinal cord all dogs had a well-defined T1 (and FLAIR) hypointense and T2 hyperintense focal dilation (isointense to the cerebrospinal fluid (CSF) within the subarachnoid space) of the dorsal subarachnoid space located at or just to the side of midline over the disc space of C2-C3. This dilation was gradually enlarging from the mid to caudal portion of C2, creating a teardrop-shaped compression over the cranial portion of C3. These lesions were interpreted as SIACs (Fig 1). The C2-C3 disc had normal signal intensity in all dogs, but was bulging mildly in five of the dogs causing mild compression of the ventral subarachnoid space, this resulted in a flattened shape of the spinal cord over the C2-C3 Journal of Small Animal Practice
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disc in these pugs. The spinal cord was comparatively larger just caudal to the area of the SIAC and then tapered to the size seen in the remainder of the cervical spine. One dog, examined at 6·5 months of age, showed an intervertebral disc degeneration at C6-C7 with minimal protrusion and no signs of spinal cord compression. All dogs had varying degrees of dilation of the central canal caudal to the SIAC. These extended over a distance of approximately one half to three vertebrae in length. The more T2 hyperintense central canal was surrounded by a more ill-defined T2 hyperintensity. This ill-defined hyperintensity was mainly seen around the cranial aspect of the lesion and interpreted as oedema. None of the pugs showed pathology in the caudal fossa, specifically no Chiari-like malformation. One pug was referred to surgery for a cervical SIAC, previously diagnosed by an MRI. However, the MRI study was not available to the surgeons. Instead a myelogram performed preoperatively showed a tear drop-shaped enlargement of the dorsal subarachnoid space over C2-C3, which is consistent with an SIAC causing spinal cord compression. Three of the pugs underwent surgery, between six and seven months of age. A dorsal laminectomy and marsupialisation of the cyst were performed. All three dogs improved after surgery. However, one pug was euthanased within 1 month postoperatively because of neurological deterioration. A pathological examination was not performed. One pug, examined 6 months postoperatively, was diagnosed with mild neurological deficits including
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were related to each other. The most recent common ancestor was a male, born in 1991 (Fig 3).
DISCUSSION
FIG 2. Cervical spinal cord at C2 with distended arachnoidal space (asterisks), focal villous arachnoidal proliferation (arrow) and distortion of the dorsal funiculi (arrowheads), H&E. x40
mild generalised ataxia without scuffing, according to the owner the dogs neurological status has remained stable for more than a year. Another pug was euthanased 1 year postoperatively because of persistent non-progressive gait abnormalities. Pathology was not performed. Two conservatively treated pugs are still alive. At the time of this study they are 3·5 years and greater than 1 year of age. According to the owner the older pug is fully ambulatory, does not show any signs of pain but is unable to walk on hard surfaces without wearing protection devices. The younger pug is ambulatory, but unable to go for regular walks due to frequent falling. Two pugs were euthanased immediately after diagnosis, one at six months and the other at one year of age. The spinal cord of the six-month-old pug was fixed in formalin and sent for histopathological evaluation. Pathological findings In the cervical spine at the level of C2-3, a distended arachnoid space with a moderate villous proliferation of meningothelial cells of the arachnoidea, a focal mild infiltration of lymphocytes and macrophages was found (Fig 2). The dorsal funiculi appeared slightly compressed, a mild dilation of myelin sheaths with axonal swelling and infiltration of few myelinophages were observed. The ventro-lateral funiculi showed mild dilation with few myelinophages. In the ventral funiculi a severe dilation of myelin sheaths with axonal swelling, few myelinophages and mild gliosis were found. The central canal was moderately to severely dilated with focal rupture of the ependymal lining. This distention of the central canal was present even at the lumbar portion of the spinal cord. The histopathological findings were suggestive of an arachnoidal diverticulum with degenerative leucomyelopathy and hydromyelia. Pedigree analysis Pedigrees were obtained from the Swedish and Norwegian Kennel Club registry (www.skk.se, www.nkk.no). The pedigrees of the affected dogs were scrutinised and compared. Seven dogs 232
The uniform phenotype combined with the young age at onset of clinical signs and the relationship between affected dogs, suggest an inherited predisposition for cervical SIACs in these pugs. Although SIACs have been reported previously in pugs (Rylander et al. 2002, Gnirs et al. 2003, Skeen et al. 2003, Chen et al. 2005, Foss et al. 2009, Oxley & Pink 2012), to the authors’ knowledge, only one has been described at this young age (Rylander et al. 2002) and all but two had the SIAC in the thoracolumbar area. In the five pugs previously reported with SIACs, in which MRI was performed, concomitant syringohydromyelia was described in two (Foss et al. 2009, Oxley & Pink 2012) (Table 1). The initial mechanism for the formation of an SIAC is not completely understood and likely multifactorial. SIACs have been shown to develop secondary to some acquired conditions (Perret et al. 1962, Gage et al. 1968, Parker & Smith 1974, Fortuna et al. 1977, Dyce et al. 1991, Bagley et al. 1997, Galloway et al. 1999, Lee & Cho 2001, Rylander et al. 2002, Gnirs et al. 2003, Wang et al. 2003, Kahraman et al. 2008). However, SIACs in younger dogs have been described as representing congenital lesions (Gnirs et al. 2003, Skeen et al. 2003, Jurina & Grevel 2004). A congenital lesion is defined as existing at or before birth (Davis 1993). It is not possible to determine whether the affected pugs developed their SIACs early in life, or if the SIACs were actually present at birth. Considering the slowly progressive nature of the neurological signs from an SIAC, it is reasonable to assume that the development of the SIAC precedes the presence of signs observed by the owners. Subtle proprioceptive deficits in a young pug may also be considered signs of immaturity and thereby dismissed by the owners. By the time the dog shows skin abrasions the SIAC is likely to have been developing for many months and may therefore indicate a congenital lesion. However, a developmental aetiology in the reported pugs cannot be excluded. A common sire was found in the pedigree of the seven affected pugs, consistent with a genetic background of SIACs in this family. A genetic susceptibility to form SIACs in dogs, due to an overrepresentation of certain breeds, has previously been suggested (Ness 1998, Frykman 1999, Rylander et al. 2002, Jurina & Grevel 2004). However, evidence of heredity has been lacking as pedigree or genetic analysis has not been performed. An MRI examination of an additional, eighth, pug with tetraparesis and scuffing of the thoracic limbs showed an SIAC dorsal to C2-C3 and a massive cervical syringohydromyelia at the age of five months. This pug was, however, not included in the case series as its pedigree was unavailable. In contrast to the majority of affected small breed dogs having thoracolumbar SIACs the cysts were located cervically in all seven pugs in this report, this is consistent with the situation in Rottweilers were SIACs have been reported in the cervical area in 13 of 15 dogs (87%) (Frykman 1999, Skeen et al. 2003, Jurina & Grevel 2004). The overrepresentation of Rottweilers suggests
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FIG 3. Pedigree of the relationship among the seven pugs affected by spinal intradural arachnoid cysts, through their most recent common ancestor (arrow). Full litters are only depicted for litters containing affected dogs. Dogs with unknown status are labelled as unaffected
a genetic predisposition to developing SIACs. It has also been linked to the dog’s conformation, e.g. the size and weight of the head (Gnirs et al. 2003). The male predominance among affected pugs may be a coincidence because of the small number of dogs, although hormonal factors or sex-linked inheritance cannot be excluded. Five of the pugs also showed mild bulging of the disc at C2-C3 causing a compression of the ventral spinal subarachnoid space. Together with the dorsal bulging of the SIAC this caused a flattening of the spinal cord in this area, which is likely to interfere with the normal flow of CSF. It might be argued that, although normally hydrated, the bulging discs could be an early sign of disc protrusion, predisposing the pugs to develop SIACs (Galloway et al. 1999). On the MRI, one of the pugs showed a T2 hypointense intervertebral disc at C6-C7 with mild protrusion. The affected pugs started to show clinical signs at around four months of age when it would conventionally be considered unlikely for disc degeneration to be clinically relevant (Hansen 1952). SIACs (Gnirs et al. 2003, Skeen et al. 2003) and degenerated discs (Rohdin et al. 2010) are, irrespectively of one another, commonly found in areas of high mobility and may explain the presence of both SIACs and bulging discs in the same area. All six dogs undergoing MRI displayed dilation of the central canal caudal to the SIACs in the cervical spinal cord. The development of syringohydromyelia is suggested to be caused Journal of Small Animal Practice
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by alterations in CSF flow within the spinal subarachnoid space (Holly et al. 2006). Syringohydromyelia has been widely reported in dogs in association with Chiari-like malformation. However, none of the pugs in this report showed any of the MRI features characterising this disorder (Dewey et al. 2004). The incidence of concurrent syringohydromyelia and SIAC is not known because many of the previously reported dogs with SIACs were not examined by MRI which is necessary for the detection of syrinx formation in vivo. As a conclusion, pedigree analysis confirmed a relationship between the dogs affected by SIACs, suggesting a genetic predisposition for the disorder in this family of pugs. Signs of a focal cervical spinal cord lesion in a young pug should alert the clinician to the possibility of cervical, spinal arachnoid cysts. Conflict of interest None of the authors of this article has a financial or personal relationship with other people or organisations that could inappropriately influence or bias the content of the paper. References Bagley, R. S., Silver, G. M., Seguin, B., et al. (1997) Scoliosis and associated cystic spinal cord lesion in a dog. Journal of the American Veterinary Medical Association 211, 573-575 Bentley, J. F., Simpson, S. T. & Hathcock, J. T. (1991) Spinal arachnoid cyst in a dog. Journal of the American Animal Hospital Association 27, 549-551
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Chauvet, A. E., Darien, D. L. & Steinberg, G. H. (1996) What is your neurologic diagnosis? Spinal abnormalities and syringomyelia of the lumbar spinal cord. Journal of the American Veterinary Medical Association 208, 1387-1389 Chen, A. V., Bagley, R. S., West, C. L., et al. (2005) Fecal incontinence and spinal cord abnormalities in seven dogs. Journal of the American Veterinary Medical Association 227, 1945-1951 Da Costa, R. C., Parent, J. M., Poma, R., et al. (2004) Cervical syringohydromyelia secondary to a brainstem tumor in a dog. Journal of the American Veterinary Medical Association 225, 1061-1064 Daneyemez, M., Gezen, F., Akbörü, M., et al. (1999) Presentation and management of supratentorial and infratentorial arachnoid cysts. Review of 25 cases. Journal of Neurosurgical Sciences 43, 115-121 Davis, F. A. (1993) Taber´s Cyclopedic Medical Dictionary. 17th edn. Ed C. L. Thomas. F. A. Davis Company, Philadelphia, PA, USA. p435 de Lahunta, A. & Glass, E. (2009a) Development of the nervous system: malformation. In: Veterinary Neuroanatomy and Clinical Neurology 3rd edn. Eds A. de Lahunta and E. Glass. W. B. Saunders, St. Louis, MO, USA. p 47 de Lahunta, A. & Glass, E. (2009b) Lower motor neuron: General somatic efferent, cranial nerve. Veterinary Neuroanatomy and Clinical Neurology 3rd edn. Eds A. de Lahunta and E. Glass. W. B. Saunders, St. Louis, MO, USA. p263 Dewey, C. W., Berg, J. M., Stefanacci, J. D., et al. (2004) Caudal occipital malformation syndrome in dogs. Compendium 886-896 Dickinson, P. J., Sturges, B. K., Berry, W. L., et al. (2001) Extradural spinal synovial cysts in nine dogs. Journal of Small Animal Practice 42, 502-509 Duque, C., Parent, J., Brisson, B., et al. (2005) Intracranial arachnoid cysts: are they clinically significant? Journal of Veterinary Internal Medicine 19, 772-774 Dyce, J., Heritage, M. E., Houlton, J. E. F., et al. (1991) Canine spinal “arachnoid cysts”. Journal of Small Animal Practice 32, 433-437 Fortuna, A., La Torre, E. & Ciapetta, P. (1977) Arachnoid diverticula: a unitary approach to spinal cysts communicating with the subarachnoid space. Acta Neurochirurgica (Wien) 39, 259-268 Foss, K. D. & Berry, W. L. (2009) What is your neurological diagnosis? Spinal arachnoid cysts. Journal of American Veterinary Medical Association 234, 1009-1011 Frykman, O. F. (1999) Spinal arachnoid cyst in four dogs: diagnosis, surgical, treatment and follow-up results. Journal of Small Animal Practice 40, 544-549 Furneaux, R. W., Doige, C. E. & Kaye, M. M. (1973) Syringomyelia and spina bifida occulta in a Samoyed dog. The Canadian Veterinary Journal 14, 317-321 Galloway, A. M., Curtis, N. C., Sommerlad, S. F., et al. (1999) Correlative imaging in seven dogs and one cat with spinal arachnoid cysts. Veterinary Radiology & Ultrasound 40, 445-452 Gage, E. D., Hoerlein, B. F. & Bartels, J. E. (1968) Spinal cord compression resulting from a leptomeningeal cyst in the dog. Journal of the American Veterinary Medical Association 152, 1664-1670 Gnirs, K., Ruel, Y., Blot, S., et al. (2003) Spinal subarachnoid cysts in 13 dogs. Veterinary Radiology & Ultrasound 44, 402-408 Goncalves, R., Hammond, G. & Penderis, J. (2008) Imaging diagnosis: erroneous localization of spinal arachnoid cyst. Veterinary Radiology & Ultrasound 49, 460-463 Hansen, H. J. (1952) A pathologic-anatomical study on disc degeneration in dog. Acta Orthopaedica Scandinavica. Supplementum (Suppl 11) 1-117 Hardie, R. J., Linn, K. A. & Rendano, V. T. (1996) Spinal meningeal cyst in a dog: a case report and literature review. Journal of the American Animal Hospital Association 32, 477-480 Hashizume, C. T. (2000) Cervical spinal arachnoid cyst in a dog. The Canadian Veterinary Journal 41, 225-227
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Holly, L. T. & Batzdorf, U. (2006) Syringomyelia associated with intradural arachnoid cysts. Journal of Neurosurgery: Spine 5, 111-116 Itamoto, K. (2010) A case involving a dog with a cervical arachnoid cyst treated with marsupilization surgery. Journal of the Japan Veterinary Medical Association 63, 375-378 Jung, D. I., Park, C., Kang, B. T., et al. (2006) Acquired cervical syringomyelia secondary to a brainstem meningioma in a Maltese dog. The Journal of Veterinary Medical Science 68, 1235-1238 Jurina, K. & Grevel, V. (2004) Spinal arachnoid pseudocysts in 10 rottweilers. Journal of Small Animal Practice 45, 9-15 Kahraman, S., Anik, I., Gocmen, S., et al. (2008) Extradural giant multiloculated arachnoid cyst causing spinal cord compression in a child. The Journal of Spinal Cord Medicine 31, 306-308 Konar, M., Lang, J., Flühmann, G., et al. (2008) Ventral intraspinal cysts associated with the intervertebral disc: magnetic resonance imaging observations in seven dogs. Veterinary Surgery 37, 94-101 Lee, H. J. & Cho, D. Y. (2001) Symtomatic spinal intradural arachnoid cysts in the pediatric age group: description of three new cases and review of the literature. Pediatric Neurosurgery 35, 181-187 McGrath, J. T. (1965) Spinal dysraphism in the dog. With comments on syringomyelia. Pathologia Veterinaria 2 (Suppl), 1-36 McKee, W. M. & Renwick, P. W. (1994) Marsupialisation of an arachnoid cyst in a dog. Journal of Small Animal Practice 35, 108-111 Ness, M. G. (1998) Spinal arachnoid cysts in two Shih Tzu littermates. The Veterinary Record 142, 515-516 Oxley, W. & Pink, J. (2012) Amelioration of caudal thoracic syringohydromyelia following surgical management of an adjacent arachnoid cyst. Journal of Small Animal Practice 53, 67-72 Parker, A. J. & Smith, C. W. (1974) Meningeal cyst in a dog. Journal of the American Animal Hospital Association 10, 595-597 Parker, A. J., Adams, W. M. & Zachary, J. F. (1983) Spinal arachnoid cysts in the dog. Journal of the American Animal Hospital Association 19, 1001-1008 Perez, B., Rollan, E., Ramiro, F., et al. (2000) Intraspinal synovial cyst in a dog. Journal of the American Animal Hospital Association 36, 235-238 Perret, G., Green, D. & Keller, J. (1962) Diagnosis and treatment of intradural arachnoid cysts of the thoracic spine. Radiology 79, 287-290 Rohdin, C., Jeserevic, J., Viitmaa, R., et al. (2010) Prevalence of radiographic detectable intervertebral disc calcifications in Dachshunds surgically treated for disc extrusion, Acta Veterinaria Scandinavica 52, 24 Rylander, H., Lipsitz, D., Berry, W. L., et al. (2002) Retrospective analysis of spinal arachnoid cysts in 14 dogs. Journal of Veterinary Internal Medicine 16, 690-696 Skeen, T. M., Olby, N. J., Muñana, K. R., et al. (2003) Spinal arachnoid cysts in 17 dogs. Journal of the American Animal Hospital Association 39, 271-282 Summers, B. A., Cummings, J. F. & deLahunta, A. (1995) Tumors of the central nervous system. In: Veterinary Neuropathology. Eds B. A. Summers, J. F. Cummings and A. de Lahunta. Mosby-Year Book, St. Louis, MO, USA. p345 Vernau, K. M., Kortz, G. D., Koblik, P. D., et al. (1997) Magnetic resonance imaging and computed tomography characteristics of intracranial intra-arachnoid cysts in 6 dogs. Veterinary Radiology & Ultrasound 38, 171-176 Vernau, K. M., LeCouteur, R. A., Sturges, B. K., et al. (2002) Intracranial intraarachnoid cyst with intracystic hemorrhage in two dogs. Veterinary Radiology & Ultrasound 43, 449-54. Wang, M. Y., Levi, A. D. & Green, B. A. (2003) Intradural spinal arachnoid cysts in adults. Surgical Neurology 60, 49-56 Webb, A. A. (1999) Intradural spinal arachnoid cyst in a dog. The Canadian Veterinary Journal 40, 588-589
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