Review Pediatr Ncurosurg 1992:18:218-223
Division of Pediatric Neurosurgery. Primary Children’s Medical Center. University of Utah. Salt Lake City, Utah. USA
The History of Ventriculoscopy: Where Do W e Go from Here?
Key Words
Abstract
Endoscopy Hydrocephalus Neuroendoscopv Third ventriculostomy Ventriculoscopy
With the availability of better endoscopes, improved lighting and increased instrumentation, the use of ventriculoscopy and ventriculostomy in the man agement of hydrocephalus is becoming increasingly more common. Neurosur geons recognized the potential for endoscopic surgery early in this century, but were frustrated in many of their attempts at treatment due to the poor quality of the instruments available. Nevertheless, much progress has been made, and the stage was set for better results with modern instrument design. This paper reviews the history of endoscopes in neurosurgery and ponders the direction these instruments will take us in the near future.
Introduction
In 1918, Dandy [1] stated that ‘hydrocephalus is a cur able disease’. Although he tried to prove this statement to be true, we know that hydrocephalus remains a major health care issue and the one with which the pediatric neurosurgeon is most commonly linked. Frustration over decisions regarding types of shunts and their proper place ment continues. Even though CSF shunting has been life saving for millions of patients, the long-term complica tions have continued to provide a stimulus to find a more physiological way of controlling CSF flow. As part of an alternative method for controlling hydro cephalus, ventriculoscopy was introduced early in this century [2-6]. However, only over the last 15-18 years have reports begun to surface indicating some success with the management of hydrocephalus using ventriculoscopic methods as opposed to permanent shunt place ment [7-12], The purpose of this paper is to review the use of ventriculoscopy and associated methods for con trolling hydrocephalus.
History
Nitze [13] in the 1870s developed a ‘train of lenses' and constructed the first endoscope. However, the exter nal diameter of the scope was greater than the effective optical diameter causing significant limitations to its practical value. Illumination for this scope was provided by a distal, incandescent light source. Improvements in design allowed Lespinasse [5] in 1910. to use a ventriculoscope to inspect the ventricles of a hydrocephalic child. In 1918. Dandy [ 1] reported on bilateral, open choroid plexectomy as an attempt to treat hydrocephalus. He reported on 4 patients. All of them survived the proce dure. but 3 of the patients died within 3 weeks of surgery. One patient, however, had a good long-term result with no further evidence of increased intracranial pressure. From that experience, he concluded that choroid plexec tomy could be of some value. In 1922, Dandy [2] described a third ventriculostomy. He did not, however, claim success for the procedure. Later in 1922, he combined these two ideas and per-
Marion L Walker, MD Division of Pediatric Neurosurgery Primary Children's Medical Center 100 N. Medical Drive Salt Lake City. UT 84113 (USA)
© 1992 S. Karger AG, Basel 1016-2291/92/0184-0218 $2.75/0
Downloaded by: Kings's College London 137.73.144.138 - 11/15/2017 10:05:08 PM
Marion L. Walker Joel MacDonald Lyn C. Wright
219
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formed the first endoscopic choroid plexectomy in 1 alus by endoscopic means must be compared with the out patient with communicating hydrocephalus [2, 14]. How comes of hydrocephalic patients treated with modern ever, he abandoned the procedure after one unsuccessful shunt systems. Guiot et al. [17], in 1963. utilized the internal reflec attempt. In 1923, Fay and Grant used a ventriculoscopc to tive properties of the solid quartz rod to devise an exter make intraventricular black and white photographs [3]. nal light source to provide a bright light to be used in ven Mixter [4], that same year, did the first successful endo triculoscopy. This enabled color photography. The effec scopic ventriculostomy. Scarff [6] became interested in tive scope diameter, however, at that time was approxi ventriculostomy during this era and developed a 'ventri mately 9 mm. The technology changed quickly. In 1974. culoscopc’ for use in cauterizing the choroid plexus. These Olinger and Ohlhaber [ 18] used a 17-gauge needle scope early attempts at ventriculoscopy, though not usually suc in the spinal canal of dogs [18], The technology available cessful in completely controlling the hydrocephalus, laid for endoscopic visualization had obviously increased sig the groundwork for others to achieve success when im nificantly. These two authors speculated on the future use of such devices. provements in design and function eventually occurred. By the late 1960s and early 1970s. as technologyIn the late 1940s and early 1950s, the development of the endoscope was greatly aided when Hopkins, a British advanced. endoscopic visualization of body areas pre optical scientist, developed a coherent fiber-optic bundle viously untried became routine. The urological surgeons for image transmisión and an incoherent bundle for light had used endoscopy for many years, but were quickly fol transmission [8]. This led to the development of the flexi lowed by their general surgical [ 19], pediatric surgical [20] ble endoscope. He also developed the ‘air-in-glass’ lens and gynecological colleagues [21], Interest in endoscopy system. The illumination through these newer endoscopes grew in orthopedics [22], otorhinolaryngology [23, 24] was significantly greater than what had been previously and cardiovascular surgery [25]. Visualization of the spi nal cord, conus and cauda equina became possible available. These basic scope designs are still used today. In 1943, Putnam [15] reported on 42 cases of endo through a 'myeloscope' developed by Pool [26, 27], In 1976, Sayers and Kosnik [28] reported on 40 cases scopic choroid plexectomy. He noted 10 perioperative deaths (25%). Fifteen patients failed to arrest their hydro of percutaneous ventriculostomy. They stressed the ne cephalus (35%), but 17 patients were reported to be suc cessity of preoperative shunting in order to achieve suc cessful in the control of their intracranial pressure. In cessful results. Vries [29], in 1978, reported the technique 1945. Dandy [ 16] reported on 52 cases of open third ven for third ventriculostomy with a fiber-optic endoscope. triculostomy. There was an operative mortality of 12%. He showed technical success in performing the ventricu Arrest of hydrocephalus, however, was reported to have lostomy. but none of the 5 patients remained shunt free over the long term. More recent attempts at the manage occurred in 50% of the patients. These early investigators were trying to arrest a disease ment of hydrocephalus with ventriculoscopic methods process that essentially had no treatment at that time. Our have shown better success. Jones et al. [11] in 1990 interpretation of the claims for success for early ventricu reported 24 patients with obstructive hydrocephalus. loscopy, third ventriculostomy and choroid plexectomy Fifty percent were able to be managed without a shunt must be tempered by the prevailing negative attitude after the performance of third ventriculostomy. toward children with hydrocephalus and their long-term successful treatment. Dandy [16] stated that 'When a Instrumentation for Ventriculoscopy child is clearly mentally defective, operative treatment is contraindicated. There can scarcely be any prospect of a At this point in time, multiple ventriculoscopic instru normal mind in a child with congenital hydrocephalus after the age of six months’. Of course we know the facts ments are available to the surgeon. Most neurosurgeons to be different today. It is obvious that early treatment of have had little if any experience with endoscopic visuali hydrocephalus affords the patient the best potential out zation as opposed to their general surgical, urological and come. Yet many patients with advanced hydrocephalus, orthopedic colleagues who use these instruments com and certainly many patients with congenital hydrocepha monly. There is a significant learning curve for the use of lus beyond 6 months of age. have been successfully man these instruments when applied to intracranial visualiza aged and have had good long-term outcomes. Judgements tion and treatment. Both rigid and flexible scopes have an regarding the effectiveness of the treatment of hydroceph appropriate place in the armamentarium of the neurosur-
Fig. 1. An example of some of the instru mentation currently available for ventricu loscopy and ventriculostomy. Flexible endo scope (large arrow); side-viewing endoscope (hollow arrow); cystoscope with bayonet at tachment (small arrow); custom vcntriculoscopc by Stortz (curved arrow).
__
Indications for Ventriculoscopy
Specific indications for ventriculoscopy can be divided into two general categories: diagnostic or therapeutic. Diagnostic indications can include biopsy and/or ana tomical surveys. Therapeutic indications at this point time include CSF communication, catheter placement, catheter and/or foreign body retrieval and tumor resec tion.
CSF Communication
The most common indication for ventriculoscopy cur rently in neurosurgery is that of opening multiloculated cysts within the ventricular system. The endoscope lends
220
itself ideally for this procedure. These cysts can be com municated with each other and into one of the ventricular cavities in order to minimize the number of shunts required. In fact, the need for one shunt versus multiple is the usual outcome following cyst communication. It has been our experience that these cysts tend to remain open after the communication has been achieved. Another form of CSF communication using ventricu loscopic methods is that of third ventriculostomy. The potential benefits for endoscopic third ventriculostomy include direct vision for the placement of the opening in the floor of the third ventricle and the availability of a variety of tools, including the laser. Third ventriculoscopy via direct vision allows the surgeon to make vital intra operative decisions regarding the placement of the fenes tration. the avoidance of vital structures and. most impor tant, the ability to discern when scarring and/or adhesions in the floor of the third ventricle makes the performance of the procedure unwise. Although third ventriculostomy can be performed rela tively easily and safely using endoscopic techniques, the selection of the ideal patient for such a procedure still remains unclear. Experience with percutaneous ventricu loscopy, however, has taught us much concerning appro priate patient selection [30-35], Theoretically, a candi date for third ventriculostomy should have normal ex traventricular CSF-absorptive pathways. There should be a noncommunicating form of hydrocephalus, no history of previous infection and no history of hemorrhage. In actual fact, however, many patients are somewhat
Walkcr/MacDonald/Wrighi
History of Ventriculoscopy
Downloaded by: Kings's College London 137.73.144.138 - 11/15/2017 10:05:08 PM
geon, but the neurosurgeon must be careful to learn proper technique before becoming too aggressive in the use of these instruments. Currently, a wide variety of instruments are available. There are rigid scopes available with an outside diameter of 2.5 mm with color balance, no distortion and ports for passage of instruments. Small, steerable, flexible ventriculoscopes with appropriate ports for instrumentation are also available. Current ventriculoscopic tools, aside from the ventri culoscopes themselves, include probes, needles, scissors, grasping forceps, aspirators, suction tubes, coagulators, laser fibers and the saline torch (fig. 1).
blended in their history and may not fit the ideal candi date. Some of these types of patients have been success fully treated using ventriculoscopic techniques. It now appears that the chances of managing hydrocephalus without shunt placement is much higher than we pre viously had estimated [11. 34], It may be that approxi mately 40% of the children seen on their initial presenta tion with hydrocephalus may be able to be managed suc cessfully by third ventriculostomy. Treatment of suprasellar arachnoid cysts by percuta neous veniriculocystostomy has been very successful [30, 36] (fig. 2). We believe that the ideal management of suprasellar arachnoid cysts is with endoscopic fenestra tion. These cysts are easily reached through an endoscope passed via the foramen of Monro. These cyst membranes are much thicker than normal arachnoid membranes. It is very difficult to pass a shunt directly into these cysts with out the shunt bouncing off and remaining external to the cyst cavity. Ventriculoscopic fenestration of suprasellar cysts will usually result in a gradual decreasing of the size of the cyst and obviate the need for shunt placement. In patients who have had long-term shunt placement prior to such fenestration, the shunt may still be required, but a shunt into the cyst cavity is not necessary.
Fig. 3. This ventricular shunt catheter was placed via direct vision with the endoscope. The placement is just above and anterior to the foramen of Monro.
Catheter Placement and Removal
Another potential use for ventriculoscopy is that of ventricular catheter placement. Under direct vision, the catheter can essentially be placed in the ‘ideal position' [37] (fig. 3). Using a peel-away catheter for ventricular puncture, through which the ventriculoscope is inserted, there is no need for a second pass through the brain paren chyma in order to achieve appropriate catheter place ment. The ventriculoscope can also be used for removal of ventricular catheters and/or foreign bodies. Retained ven tricular catheters can be freed from surrounding scar tis sue using laser dissection. Retained foreign objects, such as metal fragments, may also be retrieved when indi cated.
Tumor Resection
Although experience is limited regarding tumor resec tion with the ventriculoscope, there is no question that this is the direction in which neurosurgery is headed with the use of this instrument. Experience has already been made with the removal of colloid cysts using endoscopic
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Fig. 2. Sagittal MRI study showing a large suprasellar arachnoid cyst. The cyst has not recurred since fenestration into the lateral ven tricle by laser ventriculoscopy.
techniques [38]. As better methods for hemostasis and visualization through ventriculoscopes are achieved, the use of the ventriculoscope for tumor removal will become increasingly common.
What Is the Future?
Ventriculoscopy has proven itself to be a valuable adjunct in the armamentarium of the neurosurgeon. Learning the appropriate techniques and the appropriate selection of rigid versus flexible scopes will add to the con fidence required to use these instruments with greater skill. The question can now be asked, where do we go from here? The future of ventriculoscopy is undoubtedly inti mately associated with the development of frameless ste reotaxy and appropriate guidance systems. One of the sig nificant limitations of ventriculoscopy at the present time is that of not knowing the exact position of the tip of the intracranial portion of the endoscope. Attempts at com municating multiple cysts are often met with frustration when the surgeon visualizes a cyst or a ventricular cavity that is scarred from multiple previous surgeries, infec tions and/or hemorrhages. The surgeon may be well aware that there is a cyst beyond a memebrane, but that mem brane may have the same exact appearance as the scarred ependyma that is covering some vital brain parenchyma. Being able to differentiate between cyst wall and brain parenchyma becomes critically important. Likewise, ap proaching smaller targets with the ventriculoscope re quires a high degree of accuracy in order to avoid poten tial injury to nearby vital brain areas. We choose to do
many of our present ventriculoscopic procedures with the Brown-Roberts-Wells stereotaxic frame in order to have precise localization of the target. Frameless stereotactic guidance will free the patient from the more combersome Brown-Roberts-Wells stereotactic apparatus and provide ongoing updates for intraoperative approaches, trajecto ries and targets. At the University of Utah, we are working on adapting frameless stereotaxy to be used with ventriculoscopy. Using a machine vision technique to localize the patient’s head in space and stereotaxically join the video images with the CT and/or MRI images allows the computer to know the position of the intracranial contents in stereo taxic space. Two small light emitting diodes on the exter nal end of the ventriculoscope constantly update the video cameras and the computer so that exact trajectories, as well as the exact position of the intracranial end of the ventriculoscope can be known at all times. Thus, the sur geon. through ongoing computer updates, can know ex actly where the tip of the endoscope is located and be able to tell whether or not he is approchaing the target or brain parenchyma. Using frameless stereotaxy with continuous computer updates regarding ventriculoscopic position will ob viously increase the surgeons confidence in the use of endoscopy. With the addition of improved visualization provided by miniature television cameras on the intracra nial end of ventriculoscopes and the utilization of newer computer techniques, such as virtual reality, the function ality of these instruments will be greatly enhanced. Un questionably, we will find more and more indications for endoscopy and what is now being termed minimally inva sive surgery.
References
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6 Scarff JE: Endoscopic treatment of hydroceph alus: Description of a ventriculoscope and pre liminary report of cases. Arch Neurol Psychia try 1935;35:853-861. 7 Griffith HB: Technique of fontanelle and persutural ventriculoscopy and endoscopic ven tricular surgery in infants. Childs Brain 1975:1: 359-363. 8 Griffith HB: Endoneurosurgery. endoscopic in tracranial surgery. Proc R Soc Lond 1977:195: 261-268. 9 Guiot G: Ventriculo-cisternostomy for stenosis of the aqueduct of Sylvius. Acta Neurochir (Wien) 1973:28:275-289.
Walkcr/MacDonald/Wright
10 Heilman CB. Cohen AR: Endoscopic ventricu lar fenestration using a 'saline torch'. J Neurosurg 1991:74:224-229. 11 Jones RFC. Stening WA. Brydon M: Endo scopic third ventriculostomy. Neurosurgery 1990:26:86-92. 12 Kleinhaus S. Germann R. Sheran M, Shapiro K, Boley SJ: A role for endoscopy in the place ment of ventriculoperitoneal shunts. Surg Neu rol 1982:18:179-180. 13 Nitze M: Veränderungen an meinen elektroendoskopischen Instrumenten zur Untersuchung der männlichen Harnblase. Monat Arztl Polytechn 1887;3:60.
History of Ventriculoscopy
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1 Dandy WE: Extirpation of the choroid plexus of the lateral ventricles in communicating hy drocephalus. Ann Surg 1918:68:569-579. 2 Dandy WE: Cerebral ventriculoscopy. Bull Johns Hopkins Hosp 1922:33:189. 3 Fay T. Grant FC: Ventriculoscopy and intra ventricular photography in internal hydroceph alus. JAMA 1923;80:461-463. 4 Mixter WJ: Ventriculoscopy and puncture of the floor of the third ventricle. Boston Med Surg J 1923:188:277-278. 5 Davis L: Hydrocephalus and spina bifida: Prin ciples of Neurological Surgery. Philadelphia. Lea & Fcbigcr. pp 438-447, 1992.
22 Watanabe M. Takeda S, Ikeuchi H: Atlas of Arthroscopy. New York. Springer, 1970. 23 Ilium P. Jcppcsen F: Endoskopisk undersogelse of sinus maxillaris. Nord Med 1971:85:221. 24 Mer SS. Derbyshire AJ. Brushenko A: Fiberop tic endoscopes for examining the middle ear. Rach Otolaryngol 1967;85:387-393. 25 Greenstone SM, Shore JM. Hcringman EC: Ar terial endoscopy (artcrioscopy). Arch Surg 1966:98:811-812. 26 Pool JL: Direct visualization of dorsal nerve roots of the cauda equina by means of a myeloscope. Arch Neurol Psvchiatry 1938:59: 1308-1312. 27 Pool JL: Myeloscopy: Intraspinal endoscopy. Surgery' 1942:2:169-182. 28 Sayers MP. Kosnik EJ: Percutaneous third ventriculostomy: Experience and technique. Childs Brain 1976;2:24-30. 29 Vries JK: An endoscopic technique for third ventriculostomy. Surg Neurol 1978:9:165— 168. 30 Hirsch JF: Percutaneous ventriculocisternos tomies in noncommunicating hydrocephalus. Monogr Neurol Sci 1982:8:321-327. 3 1 Hoffman HJ: The advantages of percutaneous third ventriculostomy over other forms of sur gical treatment for infantile obstructive hydro cephalus: in Morley TP (ed): Current Contro versies in Neurosurgery. Philadelphia. Saun ders. 1976. pp 691-703.
32 Hoffman HJ. Harwood-Nash D. Gilday DL: Percutaneous third ventriculostomy in the management of non-communicating hydro cephalus. Neurosurgery 1980;7:313-321. 33 Kelly P. Gocrss S. Kail B. Kisperl D: Com puted tomography based stereotactic third ven triculostomy. Neurosurgery 1986:18:791-794. 34 Kelly PJ: Stereotactic third ventriculostomy in patients with nontumoral adolesccnt/adult on set aqucductal stenosis and symptomatic hy drocephalus. J Ncurosurg 1991;75:865-873. 35 Patterson RH. Bergland RM: The selection of patients for third ventriculostomy based on experience with 33 operations. J Neurosurg 1968:29:252-254. 36 Pierre-Kahn A. Capelle L, Sainte-Rose C, Re nier D. Hoppe-Hirsch E. Hirsch JF: Treatment of suprasellar arachnoid cysts by percutaneous transfrontal ventriculocystostomy. Apropos of 17 cases. Neurochirurgie 1990:36:370-377. 37 Vries JK: Endoscopy as an adjunct to shunting for hydrocephalus. Surg Neurol 1980:13:6972. 38 Powell MP. Torrens MJ. Thomson JLG, Horgan JG: Isodcnse colloid cysts of the third ven tricle: A diagnostic and therapeutic problem resolved by ventriculoscopy. Neurosurgery 1983:13:234-237.
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14 Dandy WE: An operative procedure for hydro cephalus. Bull Johns Hopkins Hosp 1922:33: 189-190. 15 Putnam TJ: The surgical treatment of infantile hydrocephalus. Surg Gynecol Obstet 1942:76: 171-182. 16 Dandy WE: Diagnosis and treatment of stric tures of the aqueduct of Sylvius causing hydro cephalus. Arch Surg 1945:51:1-14. 17 Guiot G, Rougeric J. FouresticrM. Fournier A. Comoy C, Vulmicre J. Groux R: Une nouvelle technique endoscopique: Explorations endos copiques intracrâniennes. Presse Méd 1963:71: 1225-1228. 18 Olinger CP. Ohlhaber RL: Eighteen-gauge mi croscopic-telescopic needle endoscope with electrode channel: Potential clinical and re search application. Surg Neurol 1974:2:151 — 160. 19 Cohen MR: The laparoscope and other equip ment: in Friedman EA (ed): Laparoscopy. Culdoscopy and Gynecography. Philadelphia. Saunders, 1970. pp 38-39. 20 Gans SL. Berci G: Advances in endoscopy of infants and children. J Pediatr Surg 1971:6: 199-233. 21 Mandelbaum R. Pontarelli D. Brushcnko A: Amnioscopy for prenatal transfusion. Am J Obstet Gynecol 1967;98:1140-1143.
Division of Pediatric Neurosurgery. Primary Children’s Medical Center. University of Utah. Salt Lake City, Utah. USA
The History of Ventriculoscopy: Where Do W e Go from Here?
Key Words
Abstract
Endoscopy Hydrocephalus Neuroendoscopv Third ventriculostomy Ventriculoscopy
With the availability of better endoscopes, improved lighting and increased instrumentation, the use of ventriculoscopy and ventriculostomy in the man agement of hydrocephalus is becoming increasingly more common. Neurosur geons recognized the potential for endoscopic surgery early in this century, but were frustrated in many of their attempts at treatment due to the poor quality of the instruments available. Nevertheless, much progress has been made, and the stage was set for better results with modern instrument design. This paper reviews the history of endoscopes in neurosurgery and ponders the direction these instruments will take us in the near future.
Introduction
In 1918, Dandy [1] stated that ‘hydrocephalus is a cur able disease’. Although he tried to prove this statement to be true, we know that hydrocephalus remains a major health care issue and the one with which the pediatric neurosurgeon is most commonly linked. Frustration over decisions regarding types of shunts and their proper place ment continues. Even though CSF shunting has been life saving for millions of patients, the long-term complica tions have continued to provide a stimulus to find a more physiological way of controlling CSF flow. As part of an alternative method for controlling hydro cephalus, ventriculoscopy was introduced early in this century [2-6]. However, only over the last 15-18 years have reports begun to surface indicating some success with the management of hydrocephalus using ventriculoscopic methods as opposed to permanent shunt place ment [7-12], The purpose of this paper is to review the use of ventriculoscopy and associated methods for con trolling hydrocephalus.
History
Nitze [13] in the 1870s developed a ‘train of lenses' and constructed the first endoscope. However, the exter nal diameter of the scope was greater than the effective optical diameter causing significant limitations to its practical value. Illumination for this scope was provided by a distal, incandescent light source. Improvements in design allowed Lespinasse [5] in 1910. to use a ventriculoscope to inspect the ventricles of a hydrocephalic child. In 1918. Dandy [ 1] reported on bilateral, open choroid plexectomy as an attempt to treat hydrocephalus. He reported on 4 patients. All of them survived the proce dure. but 3 of the patients died within 3 weeks of surgery. One patient, however, had a good long-term result with no further evidence of increased intracranial pressure. From that experience, he concluded that choroid plexec tomy could be of some value. In 1922, Dandy [2] described a third ventriculostomy. He did not, however, claim success for the procedure. Later in 1922, he combined these two ideas and per-
Marion L Walker, MD Division of Pediatric Neurosurgery Primary Children's Medical Center 100 N. Medical Drive Salt Lake City. UT 84113 (USA)
© 1992 S. Karger AG, Basel 1016-2291/92/0184-0218 $2.75/0
Downloaded by: Kings's College London 137.73.144.138 - 11/15/2017 10:05:08 PM
Marion L. Walker Joel MacDonald Lyn C. Wright
219
Downloaded by: Kings's College London 137.73.144.138 - 11/15/2017 10:05:08 PM
formed the first endoscopic choroid plexectomy in 1 alus by endoscopic means must be compared with the out patient with communicating hydrocephalus [2, 14]. How comes of hydrocephalic patients treated with modern ever, he abandoned the procedure after one unsuccessful shunt systems. Guiot et al. [17], in 1963. utilized the internal reflec attempt. In 1923, Fay and Grant used a ventriculoscopc to tive properties of the solid quartz rod to devise an exter make intraventricular black and white photographs [3]. nal light source to provide a bright light to be used in ven Mixter [4], that same year, did the first successful endo triculoscopy. This enabled color photography. The effec scopic ventriculostomy. Scarff [6] became interested in tive scope diameter, however, at that time was approxi ventriculostomy during this era and developed a 'ventri mately 9 mm. The technology changed quickly. In 1974. culoscopc’ for use in cauterizing the choroid plexus. These Olinger and Ohlhaber [ 18] used a 17-gauge needle scope early attempts at ventriculoscopy, though not usually suc in the spinal canal of dogs [18], The technology available cessful in completely controlling the hydrocephalus, laid for endoscopic visualization had obviously increased sig the groundwork for others to achieve success when im nificantly. These two authors speculated on the future use of such devices. provements in design and function eventually occurred. By the late 1960s and early 1970s. as technologyIn the late 1940s and early 1950s, the development of the endoscope was greatly aided when Hopkins, a British advanced. endoscopic visualization of body areas pre optical scientist, developed a coherent fiber-optic bundle viously untried became routine. The urological surgeons for image transmisión and an incoherent bundle for light had used endoscopy for many years, but were quickly fol transmission [8]. This led to the development of the flexi lowed by their general surgical [ 19], pediatric surgical [20] ble endoscope. He also developed the ‘air-in-glass’ lens and gynecological colleagues [21], Interest in endoscopy system. The illumination through these newer endoscopes grew in orthopedics [22], otorhinolaryngology [23, 24] was significantly greater than what had been previously and cardiovascular surgery [25]. Visualization of the spi nal cord, conus and cauda equina became possible available. These basic scope designs are still used today. In 1943, Putnam [15] reported on 42 cases of endo through a 'myeloscope' developed by Pool [26, 27], In 1976, Sayers and Kosnik [28] reported on 40 cases scopic choroid plexectomy. He noted 10 perioperative deaths (25%). Fifteen patients failed to arrest their hydro of percutaneous ventriculostomy. They stressed the ne cephalus (35%), but 17 patients were reported to be suc cessity of preoperative shunting in order to achieve suc cessful in the control of their intracranial pressure. In cessful results. Vries [29], in 1978, reported the technique 1945. Dandy [ 16] reported on 52 cases of open third ven for third ventriculostomy with a fiber-optic endoscope. triculostomy. There was an operative mortality of 12%. He showed technical success in performing the ventricu Arrest of hydrocephalus, however, was reported to have lostomy. but none of the 5 patients remained shunt free over the long term. More recent attempts at the manage occurred in 50% of the patients. These early investigators were trying to arrest a disease ment of hydrocephalus with ventriculoscopic methods process that essentially had no treatment at that time. Our have shown better success. Jones et al. [11] in 1990 interpretation of the claims for success for early ventricu reported 24 patients with obstructive hydrocephalus. loscopy, third ventriculostomy and choroid plexectomy Fifty percent were able to be managed without a shunt must be tempered by the prevailing negative attitude after the performance of third ventriculostomy. toward children with hydrocephalus and their long-term successful treatment. Dandy [16] stated that 'When a Instrumentation for Ventriculoscopy child is clearly mentally defective, operative treatment is contraindicated. There can scarcely be any prospect of a At this point in time, multiple ventriculoscopic instru normal mind in a child with congenital hydrocephalus after the age of six months’. Of course we know the facts ments are available to the surgeon. Most neurosurgeons to be different today. It is obvious that early treatment of have had little if any experience with endoscopic visuali hydrocephalus affords the patient the best potential out zation as opposed to their general surgical, urological and come. Yet many patients with advanced hydrocephalus, orthopedic colleagues who use these instruments com and certainly many patients with congenital hydrocepha monly. There is a significant learning curve for the use of lus beyond 6 months of age. have been successfully man these instruments when applied to intracranial visualiza aged and have had good long-term outcomes. Judgements tion and treatment. Both rigid and flexible scopes have an regarding the effectiveness of the treatment of hydroceph appropriate place in the armamentarium of the neurosur-
Fig. 1. An example of some of the instru mentation currently available for ventricu loscopy and ventriculostomy. Flexible endo scope (large arrow); side-viewing endoscope (hollow arrow); cystoscope with bayonet at tachment (small arrow); custom vcntriculoscopc by Stortz (curved arrow).
__
Indications for Ventriculoscopy
Specific indications for ventriculoscopy can be divided into two general categories: diagnostic or therapeutic. Diagnostic indications can include biopsy and/or ana tomical surveys. Therapeutic indications at this point time include CSF communication, catheter placement, catheter and/or foreign body retrieval and tumor resec tion.
CSF Communication
The most common indication for ventriculoscopy cur rently in neurosurgery is that of opening multiloculated cysts within the ventricular system. The endoscope lends
220
itself ideally for this procedure. These cysts can be com municated with each other and into one of the ventricular cavities in order to minimize the number of shunts required. In fact, the need for one shunt versus multiple is the usual outcome following cyst communication. It has been our experience that these cysts tend to remain open after the communication has been achieved. Another form of CSF communication using ventricu loscopic methods is that of third ventriculostomy. The potential benefits for endoscopic third ventriculostomy include direct vision for the placement of the opening in the floor of the third ventricle and the availability of a variety of tools, including the laser. Third ventriculoscopy via direct vision allows the surgeon to make vital intra operative decisions regarding the placement of the fenes tration. the avoidance of vital structures and. most impor tant, the ability to discern when scarring and/or adhesions in the floor of the third ventricle makes the performance of the procedure unwise. Although third ventriculostomy can be performed rela tively easily and safely using endoscopic techniques, the selection of the ideal patient for such a procedure still remains unclear. Experience with percutaneous ventricu loscopy, however, has taught us much concerning appro priate patient selection [30-35], Theoretically, a candi date for third ventriculostomy should have normal ex traventricular CSF-absorptive pathways. There should be a noncommunicating form of hydrocephalus, no history of previous infection and no history of hemorrhage. In actual fact, however, many patients are somewhat
Walkcr/MacDonald/Wrighi
History of Ventriculoscopy
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geon, but the neurosurgeon must be careful to learn proper technique before becoming too aggressive in the use of these instruments. Currently, a wide variety of instruments are available. There are rigid scopes available with an outside diameter of 2.5 mm with color balance, no distortion and ports for passage of instruments. Small, steerable, flexible ventriculoscopes with appropriate ports for instrumentation are also available. Current ventriculoscopic tools, aside from the ventri culoscopes themselves, include probes, needles, scissors, grasping forceps, aspirators, suction tubes, coagulators, laser fibers and the saline torch (fig. 1).
blended in their history and may not fit the ideal candi date. Some of these types of patients have been success fully treated using ventriculoscopic techniques. It now appears that the chances of managing hydrocephalus without shunt placement is much higher than we pre viously had estimated [11. 34], It may be that approxi mately 40% of the children seen on their initial presenta tion with hydrocephalus may be able to be managed suc cessfully by third ventriculostomy. Treatment of suprasellar arachnoid cysts by percuta neous veniriculocystostomy has been very successful [30, 36] (fig. 2). We believe that the ideal management of suprasellar arachnoid cysts is with endoscopic fenestra tion. These cysts are easily reached through an endoscope passed via the foramen of Monro. These cyst membranes are much thicker than normal arachnoid membranes. It is very difficult to pass a shunt directly into these cysts with out the shunt bouncing off and remaining external to the cyst cavity. Ventriculoscopic fenestration of suprasellar cysts will usually result in a gradual decreasing of the size of the cyst and obviate the need for shunt placement. In patients who have had long-term shunt placement prior to such fenestration, the shunt may still be required, but a shunt into the cyst cavity is not necessary.
Fig. 3. This ventricular shunt catheter was placed via direct vision with the endoscope. The placement is just above and anterior to the foramen of Monro.
Catheter Placement and Removal
Another potential use for ventriculoscopy is that of ventricular catheter placement. Under direct vision, the catheter can essentially be placed in the ‘ideal position' [37] (fig. 3). Using a peel-away catheter for ventricular puncture, through which the ventriculoscope is inserted, there is no need for a second pass through the brain paren chyma in order to achieve appropriate catheter place ment. The ventriculoscope can also be used for removal of ventricular catheters and/or foreign bodies. Retained ven tricular catheters can be freed from surrounding scar tis sue using laser dissection. Retained foreign objects, such as metal fragments, may also be retrieved when indi cated.
Tumor Resection
Although experience is limited regarding tumor resec tion with the ventriculoscope, there is no question that this is the direction in which neurosurgery is headed with the use of this instrument. Experience has already been made with the removal of colloid cysts using endoscopic
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Fig. 2. Sagittal MRI study showing a large suprasellar arachnoid cyst. The cyst has not recurred since fenestration into the lateral ven tricle by laser ventriculoscopy.
techniques [38]. As better methods for hemostasis and visualization through ventriculoscopes are achieved, the use of the ventriculoscope for tumor removal will become increasingly common.
What Is the Future?
Ventriculoscopy has proven itself to be a valuable adjunct in the armamentarium of the neurosurgeon. Learning the appropriate techniques and the appropriate selection of rigid versus flexible scopes will add to the con fidence required to use these instruments with greater skill. The question can now be asked, where do we go from here? The future of ventriculoscopy is undoubtedly inti mately associated with the development of frameless ste reotaxy and appropriate guidance systems. One of the sig nificant limitations of ventriculoscopy at the present time is that of not knowing the exact position of the tip of the intracranial portion of the endoscope. Attempts at com municating multiple cysts are often met with frustration when the surgeon visualizes a cyst or a ventricular cavity that is scarred from multiple previous surgeries, infec tions and/or hemorrhages. The surgeon may be well aware that there is a cyst beyond a memebrane, but that mem brane may have the same exact appearance as the scarred ependyma that is covering some vital brain parenchyma. Being able to differentiate between cyst wall and brain parenchyma becomes critically important. Likewise, ap proaching smaller targets with the ventriculoscope re quires a high degree of accuracy in order to avoid poten tial injury to nearby vital brain areas. We choose to do
many of our present ventriculoscopic procedures with the Brown-Roberts-Wells stereotaxic frame in order to have precise localization of the target. Frameless stereotactic guidance will free the patient from the more combersome Brown-Roberts-Wells stereotactic apparatus and provide ongoing updates for intraoperative approaches, trajecto ries and targets. At the University of Utah, we are working on adapting frameless stereotaxy to be used with ventriculoscopy. Using a machine vision technique to localize the patient’s head in space and stereotaxically join the video images with the CT and/or MRI images allows the computer to know the position of the intracranial contents in stereo taxic space. Two small light emitting diodes on the exter nal end of the ventriculoscope constantly update the video cameras and the computer so that exact trajectories, as well as the exact position of the intracranial end of the ventriculoscope can be known at all times. Thus, the sur geon. through ongoing computer updates, can know ex actly where the tip of the endoscope is located and be able to tell whether or not he is approchaing the target or brain parenchyma. Using frameless stereotaxy with continuous computer updates regarding ventriculoscopic position will ob viously increase the surgeons confidence in the use of endoscopy. With the addition of improved visualization provided by miniature television cameras on the intracra nial end of ventriculoscopes and the utilization of newer computer techniques, such as virtual reality, the function ality of these instruments will be greatly enhanced. Un questionably, we will find more and more indications for endoscopy and what is now being termed minimally inva sive surgery.
References
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