J Nenrosurg 73:785-787, 1990
Postlaminectomy ossified extradural pseudocyst Case report HARUO TSuJI, M.D., NORIKAZU HANDA, M.D., OiJj~ HANDA, M.D., GOHICHI TAJIMA, M.D., AND KAZUYOSHI MORI, M.D. Department of Orthopedic Surgery, Toyama Medical and Pharmaceutical University, Toyama, Japan o, A large ossified spurious meningocele accompanied by recurrent lumbar disc herniation occurred 7 years after posterior intervention for laminectomy and discectomy in a 53-year-old man. The cyst wall, histologically composed of mature bone tissue, was sparsely covered with connective tissue and lined with fibrocyte- or fibroblast-like cells on the inside. The ossified pseudocyst was presumed to have originated from a minute defect in the dura mater which occurred at the time of the first operation. KEy W o R o s 9 lumbar spine 9 ossified spurious meningocele intervertebral disc herniation 9 laminectomy
O
SSIFIED SpUriOUSmeningocele is extremely rare; to our knowledge, only two cases have been described, one by Verbiest (unpublished data) and one by Rosenblum and DerowY Extradural pseudocyst following laminectomy was first reported by Hyndman and Gerber 3 in 1946. In 1974, Pau 7 found reports of 36 cases: two of his own and 34 collected by Grumme, et al. 2 In the present paper, we report a rare ossified spurious meningocele that developed 7 years after laminectomy and discectomy for lumbar intervertebral disc herniation.
9 pseudocyst
9
ited. A posteroanterior plain x-ray film disclosed the doughnut-shaped shadow of a 5 • 5-cm ossified cystiform circle at the L4-5 level (Fig. l a). A metrizamide myelogram showed an hourglass-shaped defect which coincided with the ossified portion, with some of the contrast medium entering the cyst (Fig. lb). A computerized tomography scan after a cystogram obtained by direct injection of metrizamide into the cyst suggested the presence of an interconnection between the cyst and the subarachnoid space. Analysis of fluid withdrawn from the cyst revealed it to be clear and color-
Case Report
This 53-year-old man complained in December, 1976, of chronic recurring pain in the lower back and fight lower leg and urinary retention. In January, 1977, he was hospitalized due to increasing fight leg pain and urinary retention. Myodil myelography revealed a complete block at the L4-5 intervertebral disc level, suggesting extruded herniation of the L4-5 disc. At that time, L4-5 partial laminectomy and discectomy were performed. A large extruded mass of nucleus tissue was removed with no complications. The patient's complaints subsided after the operation; however, a slight degree of urinary retention persisted. In September, 1983, 6 89years later, pain reappeared in the lower back and right leg without apparent cause. Examination. On admission, a large palpable lump was found in the lower back. A straight-leg raising test was strongly positive on the fight side. There was noticeable hypesthesia in the fight S-1 region but no abnormalities of the deep-tendon reflexes could be elicJ. Neurosurg. / Volume 73/November, 1990
FIG. 1. Preoperative radiographs, a: X-ray film, posteroanterior view, showing a doughnut-shaped ossified shadow at the L4-5 level, b: Metrizamide myelogram revealing an hourglass-shaped defect, suggesting disc herniation. 785
H. Tsuji, et al. less with a 43 mg/dl protein content and a positive Pandy test. Operation. Surgery via a posterior approach was carried out on September 21, 1983. A 5 • 5-cm balloonshaped bone pseudocyst was found on the L-4 and L-5 vertebral arches. The outer wall of the pseudocyst was grayish white, resilient, and firm, while the surface was covered with a thin fibrous pseudocapsule. When the canopy of the cyst wall was incised there was an outflow of clear cerebrospinal fluid (CSF), but no filaments of the cauda equina were found. The cyst wall was about 2 mm thick and composed of nearly mature bone tissue. The inner side of the pseudocyst was very smooth; the bottom was of either fibrous or cartilaginous tissue and there was a small hole in the center, communicating with the subarachnoid space (Fig. 2). Although a cyst wall typically compresses the dura mater, in this case the adhesion with the dura mater was so loose that ablation could easily be performed. After removal of the pseudocyst, the recurrent extruded disc material compressing the right S-1 nerve root was removed, followed by autologous free fat grafting. Six years after the operation, the patient had no complaints of lowerback pain, but does have occasional slight pain in the left leg. Pathological Examination. The cyst wall was comprised of three layers: an inner layer of smooth sparse connective tissue lined with sparse fibrocyte- or fibroblast-like cells, an outer connective tissue layer, and mature bone tissue between them (Fig. 3). The bone tissue had formed a bone marrow and was disclosed to be primary fibrous and ossified. Discussion Among the reported cases of postoperative spurious meningocele, only 31 have been described in detail; of these, 29 cases occurred in the lumbar area and one each in the thoracic and the cervical regions. The initial operation for the 29 lumbar cases was posterior intervention for disc herniation of the lumbar spine. ~-3'5-~3 Swanson and Fincher ~ reported the incidence of spurious meningocele to be 0.068% of lumbar surgery cases. Among the 31 reported cases only two cases of ossified extradural pseudocyst have been described (Verbiest (unpublished data) and Rosenblum and Derowg). The case presented here may be only the third to be identified.
Classification and Pathogenesis Extradural pseudocysts have been categorized by Wilkinson '2 as congenital, traumatic, or postoperative. Rosenblum and Derow 9 and Hyndman and Gerber 3 classified extradural pseudocysts into two types (congenital and acquired), and cited trauma, bleeding in the dorsal muscle, and surgical intervention as possible causes of the acquired type. Miller and Elder 5 proposed the possibility that an extradural pseudocyst is a true herniation of the arachnoid membrane which has ex786
FIG. 2. Intraoperative view of the inner wall of the bottom part of the cyst showing the tiny hole by which the cyst cavity and subarachnoid space communicated. The inner surface of the cyst was made up of a white, smooth, and glossy part and bone tissue. truded through a minute fissure made during the first operation. They suggested that the size of the cyst is determined by the size of the dural defect, the CSF pressure, the resistance of the paraspinal soft tissue, and other factors. Pagni, et al., 6 asserted that a pseudocyst is formed when a chronic interconnection between the subarachnoid space and the paraspinal muscle is created as a result of intraoperative dural injury. These circumstances are not rare in posterior spinal intervention procedures 6 and it is probable that a small volume of CSF leakage is easily absorbed. When chronic CSF leakage persists, however, an abnormal connective tissue reaction may occur, resulting in the formation of a pseudocyst, ~~ which in turn inhibits the absorption of CSF. In the case reported here, however, it is thought that a large herniation of the arachnoid membrane had gradually extended through an iatrogenic defect in the dura mater. This hypothesis is supported by the fact that the inner surface of the cyst was made up of a smooth sparse connective tissue layer simulating the arachnoid membrane, whereas the arachnoid membrane was confirmed to be intact at the first operation. Histological examination of the cyst wall suggests that the ossification was primarily fibrous.
Symptomatology The clinical symptoms of a pseudocyst in the lumbar region are reported to be similar to those of previous disc herniation, ~'8'~~ which generally suggests a recurrence of the herniation. In several reports, patients have complained of headache and neck pain, presumably as symptoms of meningeal irritation, 3,5'6'8-~ which vary with coughing, posture, or percussion in the region of the cyst. Wilkinson '2 reported cases with nerve root extrusion into the cyst, causing acute leg pain. Miller and Elder 5 reported a negative correlation of the size of J. Neurosurg. / Volume 73/November, 1990
Postlaminectomy ossified extradural pseudocyst
FIG. 3. Photomicrograph of the cyst wall showing three main layers: an inner layer of smooth sparse connective tissue lined with cells (upper), a layer of mature bone tissue (center), and an outer layer of connective tissue (below). H & E, x 31. Inset shows fibrocyte- or fibroblast-like cells lining the inside of the cavity. H & E, x 125.
both the cyst and the defect in the dura mater with the degree of symptoms. It is inferred from the operative findings in our patient that the cause of pain in the right leg and lower back was nerve root compression due to the recurrent herniation with lumbar spinal stenosis, complicated by the ossified extradural pseudocyst wall.
Treatment Extirpation of extradural pseudocysts has been reported to improve symptoms significantly and to offer a good prognosis. 5'7'9"~ During posterior intervention for disc herniation, careful closure of the defect in the dura mater is critical to prevent formation of pseudocysts. 1'5'6'8 If the defect cannot be completely closed, precise and accurate grafting of autogenous fat tissue is essential. 4 References
1. Borgesen SE, Vang PS: Extradural pseudocysts. A cause of pain after lumbar disc operation. Acta Orthop Scand 44:12-20, 1973 2. Grumme T, Bingas B, Knupling R" Meningozele nach lumbaren Bandscheibenoperationen. Acta Neurochir 27: 177-187, 1972 3. Hyndman OR, Gerber WF: Spinal extradural cysts, congenital and acquired. Report of cases. J Nearosurg 3: 474-486, 1946 4. Keller JT, Ongkiko CM Jr, Saunders MC, et al: Report
J. Neurosurg. / Volume 73/November, 1990
5. 6. 7. 8. 9. 10. 11. 12. l 3.
of spinal dural defects. An experimental study. J Neurosurg 60:1022-1028, 1984 Miller PR, Elder FW Jr: Meningeal pseudocysts (meningocele spurious) following laminectomy. Report of ten cases. J Bone Joint Surg (Am) 50:268-276, 1968 Pagni CA, Cassinari V, Bernasconi V: Meningocele spurius following hemilaminectomy in a case of lumbar discal hernia. J Neurosurg 18:709-710, 1961 Pau A: Postoperative meningocele spurius: report of two cases. J Nenrosurg Sei 18:150-152, 1974 Rinaldi I, Peach WF Jr: Postoperative lumbar meningocele. Report of two cases. J Neurosurg 30:504-507, 1969 Rosenblum DJ, Derow JR: Spinal extradural cysts, with report of an ossified spinal extradural cyst. AJR 90: 1227-1230, 1963 Shahinfar AH, Schechter MM: Traumatic extradural cysts of the spine. AJR 98:713-719, 1966 Swanson HS, Fincher EF: Extradural arachnoidal cysts of traumatic orgin. J Neurosurg 4:530-538, 1947 Wilkinson HA: Nerve-root entrapment in traumatic extradural arachnoid cyst. J Bone Joint Surg (Am) 53: 163-166, 1971 Winkler H, Powers JA: Meningocele following hemilaminectomy. A report of two cases. NC Med J 11: 292-294, 1950
Manuscript received January 5, 1990. Address reprint requests to: Haruo Tsuji, M.D., Department of Orthopedic Surgery, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama 930-01, Japan.
787
Postlaminectomy ossified extradural pseudocyst Case report HARUO TSuJI, M.D., NORIKAZU HANDA, M.D., OiJj~ HANDA, M.D., GOHICHI TAJIMA, M.D., AND KAZUYOSHI MORI, M.D. Department of Orthopedic Surgery, Toyama Medical and Pharmaceutical University, Toyama, Japan o, A large ossified spurious meningocele accompanied by recurrent lumbar disc herniation occurred 7 years after posterior intervention for laminectomy and discectomy in a 53-year-old man. The cyst wall, histologically composed of mature bone tissue, was sparsely covered with connective tissue and lined with fibrocyte- or fibroblast-like cells on the inside. The ossified pseudocyst was presumed to have originated from a minute defect in the dura mater which occurred at the time of the first operation. KEy W o R o s 9 lumbar spine 9 ossified spurious meningocele intervertebral disc herniation 9 laminectomy
O
SSIFIED SpUriOUSmeningocele is extremely rare; to our knowledge, only two cases have been described, one by Verbiest (unpublished data) and one by Rosenblum and DerowY Extradural pseudocyst following laminectomy was first reported by Hyndman and Gerber 3 in 1946. In 1974, Pau 7 found reports of 36 cases: two of his own and 34 collected by Grumme, et al. 2 In the present paper, we report a rare ossified spurious meningocele that developed 7 years after laminectomy and discectomy for lumbar intervertebral disc herniation.
9 pseudocyst
9
ited. A posteroanterior plain x-ray film disclosed the doughnut-shaped shadow of a 5 • 5-cm ossified cystiform circle at the L4-5 level (Fig. l a). A metrizamide myelogram showed an hourglass-shaped defect which coincided with the ossified portion, with some of the contrast medium entering the cyst (Fig. lb). A computerized tomography scan after a cystogram obtained by direct injection of metrizamide into the cyst suggested the presence of an interconnection between the cyst and the subarachnoid space. Analysis of fluid withdrawn from the cyst revealed it to be clear and color-
Case Report
This 53-year-old man complained in December, 1976, of chronic recurring pain in the lower back and fight lower leg and urinary retention. In January, 1977, he was hospitalized due to increasing fight leg pain and urinary retention. Myodil myelography revealed a complete block at the L4-5 intervertebral disc level, suggesting extruded herniation of the L4-5 disc. At that time, L4-5 partial laminectomy and discectomy were performed. A large extruded mass of nucleus tissue was removed with no complications. The patient's complaints subsided after the operation; however, a slight degree of urinary retention persisted. In September, 1983, 6 89years later, pain reappeared in the lower back and right leg without apparent cause. Examination. On admission, a large palpable lump was found in the lower back. A straight-leg raising test was strongly positive on the fight side. There was noticeable hypesthesia in the fight S-1 region but no abnormalities of the deep-tendon reflexes could be elicJ. Neurosurg. / Volume 73/November, 1990
FIG. 1. Preoperative radiographs, a: X-ray film, posteroanterior view, showing a doughnut-shaped ossified shadow at the L4-5 level, b: Metrizamide myelogram revealing an hourglass-shaped defect, suggesting disc herniation. 785
H. Tsuji, et al. less with a 43 mg/dl protein content and a positive Pandy test. Operation. Surgery via a posterior approach was carried out on September 21, 1983. A 5 • 5-cm balloonshaped bone pseudocyst was found on the L-4 and L-5 vertebral arches. The outer wall of the pseudocyst was grayish white, resilient, and firm, while the surface was covered with a thin fibrous pseudocapsule. When the canopy of the cyst wall was incised there was an outflow of clear cerebrospinal fluid (CSF), but no filaments of the cauda equina were found. The cyst wall was about 2 mm thick and composed of nearly mature bone tissue. The inner side of the pseudocyst was very smooth; the bottom was of either fibrous or cartilaginous tissue and there was a small hole in the center, communicating with the subarachnoid space (Fig. 2). Although a cyst wall typically compresses the dura mater, in this case the adhesion with the dura mater was so loose that ablation could easily be performed. After removal of the pseudocyst, the recurrent extruded disc material compressing the right S-1 nerve root was removed, followed by autologous free fat grafting. Six years after the operation, the patient had no complaints of lowerback pain, but does have occasional slight pain in the left leg. Pathological Examination. The cyst wall was comprised of three layers: an inner layer of smooth sparse connective tissue lined with sparse fibrocyte- or fibroblast-like cells, an outer connective tissue layer, and mature bone tissue between them (Fig. 3). The bone tissue had formed a bone marrow and was disclosed to be primary fibrous and ossified. Discussion Among the reported cases of postoperative spurious meningocele, only 31 have been described in detail; of these, 29 cases occurred in the lumbar area and one each in the thoracic and the cervical regions. The initial operation for the 29 lumbar cases was posterior intervention for disc herniation of the lumbar spine. ~-3'5-~3 Swanson and Fincher ~ reported the incidence of spurious meningocele to be 0.068% of lumbar surgery cases. Among the 31 reported cases only two cases of ossified extradural pseudocyst have been described (Verbiest (unpublished data) and Rosenblum and Derowg). The case presented here may be only the third to be identified.
Classification and Pathogenesis Extradural pseudocysts have been categorized by Wilkinson '2 as congenital, traumatic, or postoperative. Rosenblum and Derow 9 and Hyndman and Gerber 3 classified extradural pseudocysts into two types (congenital and acquired), and cited trauma, bleeding in the dorsal muscle, and surgical intervention as possible causes of the acquired type. Miller and Elder 5 proposed the possibility that an extradural pseudocyst is a true herniation of the arachnoid membrane which has ex786
FIG. 2. Intraoperative view of the inner wall of the bottom part of the cyst showing the tiny hole by which the cyst cavity and subarachnoid space communicated. The inner surface of the cyst was made up of a white, smooth, and glossy part and bone tissue. truded through a minute fissure made during the first operation. They suggested that the size of the cyst is determined by the size of the dural defect, the CSF pressure, the resistance of the paraspinal soft tissue, and other factors. Pagni, et al., 6 asserted that a pseudocyst is formed when a chronic interconnection between the subarachnoid space and the paraspinal muscle is created as a result of intraoperative dural injury. These circumstances are not rare in posterior spinal intervention procedures 6 and it is probable that a small volume of CSF leakage is easily absorbed. When chronic CSF leakage persists, however, an abnormal connective tissue reaction may occur, resulting in the formation of a pseudocyst, ~~ which in turn inhibits the absorption of CSF. In the case reported here, however, it is thought that a large herniation of the arachnoid membrane had gradually extended through an iatrogenic defect in the dura mater. This hypothesis is supported by the fact that the inner surface of the cyst was made up of a smooth sparse connective tissue layer simulating the arachnoid membrane, whereas the arachnoid membrane was confirmed to be intact at the first operation. Histological examination of the cyst wall suggests that the ossification was primarily fibrous.
Symptomatology The clinical symptoms of a pseudocyst in the lumbar region are reported to be similar to those of previous disc herniation, ~'8'~~ which generally suggests a recurrence of the herniation. In several reports, patients have complained of headache and neck pain, presumably as symptoms of meningeal irritation, 3,5'6'8-~ which vary with coughing, posture, or percussion in the region of the cyst. Wilkinson '2 reported cases with nerve root extrusion into the cyst, causing acute leg pain. Miller and Elder 5 reported a negative correlation of the size of J. Neurosurg. / Volume 73/November, 1990
Postlaminectomy ossified extradural pseudocyst
FIG. 3. Photomicrograph of the cyst wall showing three main layers: an inner layer of smooth sparse connective tissue lined with cells (upper), a layer of mature bone tissue (center), and an outer layer of connective tissue (below). H & E, x 31. Inset shows fibrocyte- or fibroblast-like cells lining the inside of the cavity. H & E, x 125.
both the cyst and the defect in the dura mater with the degree of symptoms. It is inferred from the operative findings in our patient that the cause of pain in the right leg and lower back was nerve root compression due to the recurrent herniation with lumbar spinal stenosis, complicated by the ossified extradural pseudocyst wall.
Treatment Extirpation of extradural pseudocysts has been reported to improve symptoms significantly and to offer a good prognosis. 5'7'9"~ During posterior intervention for disc herniation, careful closure of the defect in the dura mater is critical to prevent formation of pseudocysts. 1'5'6'8 If the defect cannot be completely closed, precise and accurate grafting of autogenous fat tissue is essential. 4 References
1. Borgesen SE, Vang PS: Extradural pseudocysts. A cause of pain after lumbar disc operation. Acta Orthop Scand 44:12-20, 1973 2. Grumme T, Bingas B, Knupling R" Meningozele nach lumbaren Bandscheibenoperationen. Acta Neurochir 27: 177-187, 1972 3. Hyndman OR, Gerber WF: Spinal extradural cysts, congenital and acquired. Report of cases. J Nearosurg 3: 474-486, 1946 4. Keller JT, Ongkiko CM Jr, Saunders MC, et al: Report
J. Neurosurg. / Volume 73/November, 1990
5. 6. 7. 8. 9. 10. 11. 12. l 3.
of spinal dural defects. An experimental study. J Neurosurg 60:1022-1028, 1984 Miller PR, Elder FW Jr: Meningeal pseudocysts (meningocele spurious) following laminectomy. Report of ten cases. J Bone Joint Surg (Am) 50:268-276, 1968 Pagni CA, Cassinari V, Bernasconi V: Meningocele spurius following hemilaminectomy in a case of lumbar discal hernia. J Neurosurg 18:709-710, 1961 Pau A: Postoperative meningocele spurius: report of two cases. J Nenrosurg Sei 18:150-152, 1974 Rinaldi I, Peach WF Jr: Postoperative lumbar meningocele. Report of two cases. J Neurosurg 30:504-507, 1969 Rosenblum DJ, Derow JR: Spinal extradural cysts, with report of an ossified spinal extradural cyst. AJR 90: 1227-1230, 1963 Shahinfar AH, Schechter MM: Traumatic extradural cysts of the spine. AJR 98:713-719, 1966 Swanson HS, Fincher EF: Extradural arachnoidal cysts of traumatic orgin. J Neurosurg 4:530-538, 1947 Wilkinson HA: Nerve-root entrapment in traumatic extradural arachnoid cyst. J Bone Joint Surg (Am) 53: 163-166, 1971 Winkler H, Powers JA: Meningocele following hemilaminectomy. A report of two cases. NC Med J 11: 292-294, 1950
Manuscript received January 5, 1990. Address reprint requests to: Haruo Tsuji, M.D., Department of Orthopedic Surgery, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama 930-01, Japan.
787
