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Spinal pseudomeningoceles and fistulas

DANIEL COUTURE, M.D., AND CHARLES L. BRANCH, JR., M.D. Department of , Wake Forest University School of Medicine, Winston-Salem, North Carolina

Spinal pseudomeningoceles and cerebrospinal fluid (CSF) fistulas are rare extradural collections of CSF that result following a breach in the dural–arachnoid layer. They may occur due to an incidental durotomy, during intradural sur- gery, or from trauma or congenital abnormality. The majority are iatrogenic and occur in the posterior lumbar region following . Although they are often asymptomatic, they may cause low-, , and even nerve root entrapment. Leakage of CSF from the wound may cause a fistulous tract, which is a conduit for infection and should be repaired immediately. Diagnosis can be confirmed on clinical examination or imaging studies including magnetic resonance imaging, computerized tomography myelography, and radionuclide myelography. Treatment must be specific to each patient because the timing, size, symptoms, and location of the dural breach all affect the choice of therapy. Nonsurgical meth- ods may be used, but more frequently operative repair is required. In this article, the authors review the diagnosis and treatment of spinal pseudomeningoceles and CSF fistulas.

KEY WORDS • pseudomeningocele • cerebrospinal fluid fistula • incidental durotomy

Spinal pseudomeningoceles and CSF fistulas are reviewed data from 3038 lumbar discectomy operations caused by similar mechanisms and can be considered and found the incidence of durotomy during bone removal to be on a continuum. A precise definition of a pseudo- or retraction to be 5.9%. The true incidence of pseudo- meningocele is difficult given the various mechanisms meningoceles following incidental durotomy is unknown that have been used to explain its pathophysiology. A because many cases are asymptomatic. Schumacher, et true meningocele is an extradural collection of CSF in an al.,54 reported the incidence of pseudomeningoceles to be arachnoid-lined capsule. Most investigators would define less than 0.1% in a study of 3000 patients who had un- a pseudomeningocele as an extradural collection of CSF dergone lumbar laminectomy. Note that the incidence is that results from a dural breach. This extradural fluid may much higher in more complicated cases such as spinal be contained in an arachnoid-lined membrane or a fi- dysraphism or dural scarring, which can occur in patients brous capsule. Other names for a pseudomeningocele in- who have undergone previous surgery or radiation treat- clude “pseudocyst,” “false cyst,” and “meningocele spuri- ment.64 Zide, et al.,63 described a 43% incidence of pseu- ous.”39,45,47 A CSF fistula results if the extradural fluid domeningoceles and a 13% incidence of CSF fistulas in communicates with the external environment or with patients undergoing release of a tethered . some other body cavity. There is also a high incidence of postoperative pseudo- meningoceles in patients who have undergone certain cer- Incidence of Pseudomeningoceles vical procedures. Treatment of ossification of the posteri- or longitudinal ligament is linked to particular risk, with By far, the majority of pseudomeningoceles are iatro- an incidence ranging from 4.5 to 32%.34,57 genic, resulting from incidental durotomies during spinal or intradural surgery. Incidental durotomy is a frequent complication of lumbar spine surgery, with a reported PATHOPHYSIOLOGICAL FEATURES incidence between 0.3 and 13%.24,31,42,43 Oppel, et al.,43 A pseudomeningocele can occur any time there is an opening of the dura mater. It can be occult or apparent and Abbreviation used in this paper: CSF = cerebrospinal fluid. found incidentally or purposely. Its most common cause is

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Unauthenticated | Downloaded 09/29/21 08:00 PM UTC D. Couture and C. L. Branch by far iatrogenic, but traumatic and congenital causes may a high incidence of dural tears and CSF leaks.59 also be implicated.2,6,10,12,17,23 During extradural surgery Congenital disorders such as neurofibromatosis and such as a laminectomy, the dura may be breached Marfan syndrome have also been associated with pseu- by direct trauma, excessive dural or nerve root traction, domeningoceles.49 Note that patients with such disorders or dural laceration from sharp bone fragments. Lumbar often have true meningoceles rather than pseudomeningo- puncture, inadvertent dural puncture after placing an epi- celes. It is believed that pseudomeningoceles form due dural catheter, or myelography needle puncture are other to CSF pulsations on a more elastic dura. Dural ectasia is causes of CSF leaks. In cases that require invasion into the frequently present in Marfan syndrome, although often it dura, such as repair of a tethered cord or resection of intra- causes no symptoms. Congenital pseudomeningoceles are dural tumors, a dural defect may occur if a watertight clo- frequently located anteriorly and are associated with de- sure has not been achieved. Leakage may result even if fects in the vertebral bodies. one recognizes improper suturing of dural defects, partic- ularly in anterior defects, which are difficult to repair. Clinical Features Cerebrospinal fluid fistulas occur in the immediate postoperative period when fluid communicates through Patients with pseudomeningoceles and CSF fistulas the wound. Occasionally, there is very low fluid flow present with a wide variety of signs and symptoms. The and it is difficult to detect the fistula. Pseudomeningoceles diagnosis of a cutaneous CSF fistula can often be made by are caused by the egress of CSF into the soft tissue, but not inspection of the wound. A watery discharge from the through the skin closure, eventually forming a fibrous wound, especially if the discharge is augmented during capsule. When the dura is breached but the arachnoid re- the Valsalva maneuver or associated with , are mains intact, the arachnoid can become herniated through common signs of a fistula. Headaches are believed to be the dura and an arachnoid-lined sac becomes the pseudo- the result of a reduction in CSF volume and lowered in- meningocele. The CSF pulsations can push the pseudo- tracranial pressure, which in turn causes traction on the meningocele into the soft tissue and affect its size, shape, meninges and blood vessels and pain. Frequently, a halo and location. sign—a light brown halo that surrounds a central stain on Different theories exist as to the likelihood of a connec- bedding or another absorbent surface—is present. A sam- tion remaining patent. One theory holds that when intact ple of the fluid may be sent for laboratory examination, a arachnoid herniates through the dura, it is more likely for very sensitive and specific test, to determine if 2 trans- the communication to remain open and form a pseudo- ferrin is present. Note that 2 transferrin is a protein iso- meningocele; if an arachnoid tear occurs as well, it is more form arising by the action of cerebral neuraminidase and likely that the communication will close.58 Others assert is found only in the central . A very small that the volume of leaked fluid is most important; for ex- sample of fluid is required ( 1 ml) and no special han- ample, with a small leak the fluid is more easily absorbed dling is needed.50 Measuring the glucose level is an unre- and the dura heals more readily.60 Another theory holds liable method, as is comparing the serum and fluid chlo- that a ball-valve mechanism can lead to a one-way flow of ride levels. Fever or meningismus indicates bacterial or CSF and thus a higher probability of developing a pseudo- aseptic . meningocele.8 As stated previously, pseudomeningoceles are often The majority of dural tears heal spontaneously, but cer- asymptomatic; however, they can be diagnosed based on tain conditions can prevent healing. Large dural defects, a subcutaneous or subfascial fluid collection that increas- poor overlying soft tissue coverage (as in dysraphism), es with Valsalva maneuvers such as sneezing and cough- scar tissue, radiation, infection, nutritional deficits, steroid ing. Cervical and thoracic pseudomeningoceles are more agents, and elevated CSF pressure can all contribute to easily palpable than lumbar ones, but occasionally lumbar poor healing of dural tears. Occasionally, nerve roots can collections can track into the subcutaneous tissues. Ser- herniate out of the sac and cause pain and radicular symp- oma, liquefied hematoma, wound infection, and toms in addition to preventing healing of the breach. should be ruled out to reach a definite diagnosis. Patients Traumatic causes of CSF fistulas and pseudomeningo- with pseudomeningoceles can present with localized back celes are rarer and their true incidence is unknown. pain and postural headaches. Localized nerve root entrap- The majority of these entities occur after an injury to the ment, herniation, or adhesions can produce pain or radic- brachial or lumbar plexus because the nerve roots are ular symptoms even several weeks or months after anchored between two mobile parts.13 Stretching of the surgery.1,16,42,51,62 Authors of several case reports have nerve root causes avulsion and ultimately the develop- described patients with progressive , including ment of a nerve root meningocele. In such cases, the one patient who was found to have spinal cord herniation arachnoid and dura that invest the nerve root are torn and into the pseudomeningocele together with cardiac and res- CSF leaks into the soft tissue surrounding the nerve, thus piratory effects that caused bulging.4,8,15,19,20,22 framing a cavity. Wallerian degeneration and CSF pulsa- tions may lead to enlargement of the cavity. Sporadic Imaging Studies cases of pseudomeningoceles following blunt trauma, which are not related to nerve roots, have been described A patient history and physical examination can be aug- but are much rarer.3,7,25,33,41,44,65 Although there is a high rate mented by imaging studies to localize the CSF fistula tract of dural tears following thoracolumbar burst fractures, or pseudomeningocele. Magnetic resonance imaging is these tears rarely progress to pseudomeningoceles or CSF the diagnostic study of choice because of its ability to fistulas.7 In contrast, penetrating injuries to the spine have visualize soft tissue. Note that magnetic resonance imag-

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ing typically reveals low signal intensity on T1-weighted Surgical Treatment images and high signal intensity on T2-weighted images, Surgical dural repair is the definitive treatment for CSF which is consistent with CSF. These images may dem- fistulas and pseudomeningoceles. It should be the prima- onstrate the level of communication with the thecal sac ry treatment undertaken in patients with profuse leaking of as well as spinal cord compression or nerve root entrap- 22,29 CSF or symptomatic pseudomeningoceles. It is also indi- ment. cated after the failure of conservative treatment. Careful Computerized tomography myelography is sometimes better for visualizing the location of the pseudomenin- imaging studies should be obtained to determine the loca- gocele or fistulous communication relative to the surgical tion of the dural breach. If a pseudomeningocele is pres- site because of its ability to demonstrate bone. Occa- ent, it should be delineated and the wall should be entered. sionally, calcification or erosion into the bone is ap- Any nerve roots present should be freed and reduced into parent.29,53,54,60 Delayed computerized tomography myelo- the dura. The durotomy site should be protected with a graphy is useful in detecting a slow-filling cottonoid, and additional exposure and bone removal pseudomeningocele.29 Nerve root pseudomeningoceles should be performed if necessary. Historically, some sur- can also be revealed on myelography. Retrograde radionu- geons have treated a small defect by merely opening the clide myelography can be used to detect pleural fistulas or dura mater widely to prevent a ball-valve effect; however, slow, intermittent leaks after lumbar puncture or traumat- most surgeons recommend primary closure of the dura. ic injury.9,18,21,26 The dura should be closed primarily with a nonab- sorbable suture on a taper or reverse cutting needle. If a large defect is present, a patch of fascia or cadaveric dura Avoidance and Conservative Treatment mater should be used to allow direct closure without com- The avoidance of iatrogenic pseudomeningoceles and pression of the neural elements. Several adjuvant agents CSF fistulas can be achieved with a careful surgical tech- have been used in addition to suturing to assist in dural nique and the use of an intraoperative microscope. If a healing. DuraGen, autologous fibrin glue, TachoComb, breach in the dura mater does occur, it should be closed Tisseal, BioGlue, and other agents have all been success- with a watertight primary closure. fully used in treatment. Either Gelfoam or muscle alone Bedrest is frequently the first step in the conservative placed over the dural breach is ineffective in stopping the management of pseudomeningoceles and CSF fistulas. leak.39,40,51,55 Fibrin sealant alone can withstand high hydro- Oversewing of the wound is required in the case of a CSF static pressures, but is effective for only 6 to 7 days and fistula. Data from studies have shown the resolution of a thus must be supplemented with a dural, muscle, or fat CSF fistula with bedrest and a watertight skin closure.36,61 graft.5,14,48 A pedicle flap is rarely required in closing the The routine or prophylactic use of antibiotic agents has defect. Placement of a drain is controversial because it not been shown to decrease the incidence of meningi- may lead to a persistent communication between the tis and, in fact, contributes to multidrug-resistant organ- extradural and intradural space. Postoperative bedrest is isms.13 Abdominal binders and focal compression have generally recommended for several days in patients with been shown to be helpful in the treatment of pseudo- lumbar defects. meningocele.32 A suboccipital pseudomeningocele has Some durotomies, such as anterior or far-lateral ones, been treated successfully with a compression dressing and occur in surgically inaccessible areas. In these cases a drainage of the collected fluid.38 midline durotomy can be made to allow for the placement An epidural blood patch is a well-known modality of of a muscle or fat graft that may be pulled into the defect. treating intracranial hypotension due to lumbar puncture Shunt insertion (ventriculoperitoneal or lumboperitoneal) or epidural injection. It has also been used successfully to should be reserved for patients with impaired CSF absorp- treat postoperative CSF fistulas and pseudomeningoce- tion or those with a pleural fistula or a fistula at the occip- les.30,35 The injection of blood promotes clot formation ital–cervical junction, which require a complicated repair. over the dural tear. Note that clot formation has been found to be increased in the presence of CSF.11,52 The clot helps to prevent CSF efflux and allows the dura to heal.37 Data from several reports have demonstrated that epidur- al patching with the aid of fibrin glue can also be used for CONCLUSIONS treatment.27,46 Pseudomeningoceles and CSF fistulas are rare com- Closed subarachnoid drainage has been successfully plications that are usually caused iatrogenically following used in the treatment of CSF fistulas and pseudomeningo- lumbar surgery. Although these entities are frequently celes. The diversion of CSF decreases the CSF pressure asymptomatic, they can be associated with a range of differential between the intradural and extradural space, signs and symptoms including headaches, infection, back allowing the dural breach to heal. Drainage of 120 to 360 pain, radiculopathy, and myelopathy. Magnetic resonance cc/day for 3 to 5 days has a 90 to 92% success rate in the imaging is the neurodiagnostic modality of choice, but treatment of a CSF fistula.28,36,56 Lumbar drains are not computerized tomography myelography and radionuclide without complications and involve a risk of spinal head- myelography may be helpful in difficult cases. A meticu- aches (60%), infection such as meningitis (2.5%), discitis lous technique during the original surgery and a watertight (5%), and wound infection (2.5%), transient nerve root closure in the event of durotomy are key. If one encoun- irritation, and recurrence.56 Diversion of CSF alone may ters either of these entities, bedrest, epidural patch with not be sufficient, and frequently the combination of CSF blood or fibrin glue, and CSF diversion may be attempted, diversion and epidural blood patch is required.37 although direct surgical repair is the definitive treatment.

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References results of lumbar spine surgery complicated by unintended inci- dental durotomy. Spine 14:443–446, 1989 1. Aldrete JA, Ghaly R: Postlaminectomy pseudomeningocele. An 25. Kachooie A, Bloch R, Banna M: Post-traumatic dorsal unsuspected cause of low back pain. Reg Anesth 20:75–79, pseudomeningocele. J Can Assoc Radiol 36:262–263, 1985 1995 26. Kadrie H, Driedger AA, McInnis W: Persistent dural cere- 2. Barberá J, Broseta J, Argüelles F, et al: Traumatic lumbosacral brospinal fluid leak shown by retrograde radionuclide myelog- meningocele. Case report. J Neurosurg 46:536–541, 1977 raphy: case report. J Nucl Med 17:797–799, 1976 3. Barnett HG, Connolly ES: Lumbosacral nerve root avulsion: 27. Kamada M, Fujita Y, Ishii R, et al: Spontaneous intracranial report of a case and review of the literature. J Trauma 15: hypotension successfully treated by epidural patching with fi- 532–535, 1975 brin glue. Headache 40:844–847, 2000 4. Burres KP, Conley FK: Progressive neurological dysfunction 28. Kitchel SH, Eismont FJ, Green BA: Closed subarachnoid secondary to postoperative cervical pseudomeningocele in a drainage for management of cerebrospinal fluid leakage after C-4 quadriplegic. Case report. J Neurosurg 48:289–291, 1978 an operation on the spine. J Bone Joint Surg Am 71:984–987, 5. Cain JE Jr, Rosenthal HG, Broom MJ, et al: Quantification of 1989 leakage pressures after durotomy repairs in the canine. Spine 29. Lau KK, Stebnyckyj M, McKenzie A: Post-laminectomy pseu- 15:969–970, 1990 domeningocele: an unusual cause of bone erosion. Australas 6. Carlson DH, Hoffman HB: Lumbosacral traumatic meningo- Radiol 36:262–264, 1992 cele. Report of a case. Neurology 21:174–176, 1971 30. Lauer KK, Haddox JD: Epidural blood patch as treatment for a 7. Cammisa FP Jr, Eismont FJ, Green BA: Dural laceration occur- surgical durocutaneous fistula. J Clin Anesth 4:45–47, 1992 ring with burst fractures and associated laminar fractures. J 31. Lee KS, Hardy IM II: Postlaminectomy lumbar pseudomenin- Bone Joint Surg Am 71:1044–1052, 1989 gocele: report of four cases. Neurosurgery 30:111–114, 1992 8. Cobb C III, Ehni G: Herniation of the spinal cord into an ia- 32. Leis AA, Leis JM, Leis JR: Pseudomeningoceles: a role of me- trogenic meningocele. Case report. J Neurosurg 39:533–536, chanical compression in the treatment of dural tears. Neurology 1973 56:1116–1117, 2001 9. Colletti PM, Siegel ME: Posttraumatic lumbar cerebrospinal 33. Louw JA: Traumatic atlanto-axial pseudomeningocele. A case fluid leak: detection by retrograde In-111-dTPA myeloscintog- report. S Afr J Surg 29:26–27, 1991 raphy. Clin Nucl Med 6:403–404, 1981 34. Macdonald RL, Fehlings MG, Tator CH, et al: Multilevel ante- 10. Cook DA, Heiner JP, Breed AL: Pseudomeningocele following rior cervical corpectomy and fibular allograft fusion for cervi- spinal fracture. A case report and review of the literature. Clin cal myelopathy. J Neurosurg 86:990–997, 1997 Orthop 247:74–79, 1989 35. Maycock NF, van Essen J, Pfitzner J: Post-laminectomy cere- 11. Cook MA, Watkins-Pitchford JM: Epidural blood patch: a rapid brospinal fluid fistula treated with epidural blood patch. Spine coagulation response. Anesth Analg 70:567–568, 1990 19:2223–2225, 1994 12. Dolynchuk KN, Teskey J, West M: Intrathoracic meningocele 36. McCallum JE, Tenicela R, Jannetta PJ: Closed external drain- associated with neurofibromatosis: case report. Neurosurgery age of cerebrospinal fluid in treatment of postoperative CSF fis- 27:485–487, 1990 tulae. Surg Forum 24:465–467, 1973 13. Eljamel MS: Antibiotic prophylaxis in unrepaired CSF fistulae. 37. McCormack BM, Taylor SL, Heath S, et al: Pseudomenin- Br J Neurosurg 7:501–505, 1993 gocele/CSF fistula in a patient with lumbar spinal implants 14. Epstein NE, Hollingsworth R: Anterior cervical micro-dural treated with epidural blood patch and a brief course of closed repair of cerebrospinal fluid fistula after surgery for ossification subarachnoid drainage. A case report. Spine 21: 2273–2276, of the posterior longitudinal ligament. Technical note. Surg 1996 Neurol 52:511–514, 1999 38. McCormack BM, Zide BM, Kalfas IH: Cerebrospinal fluid fis- 15. Goodman SJ, Gregorius FK: Cervical pseudomeningocele after tula and pseduomeningocele after spine surgery, in Benzel EC laminectomy as a cause of progressive myelopathy. Bull Los (ed): Spine Surgery: Techniques, Complication Avoidance Angeles Neurol Soc 39:121–127, 1974 and Management. Philadelphia: Churchill Livingstone, 1999, 16. Hadani M, Findler G, Knoler N, et al: Entrapped lumbar nerve Vol 2, pp 1465–1474 root in pseudomeningocele after laminectomy: report of three 39. Miller PR, Elder FW Jr: Meningeal pseudocysts (meningocele cases. Neurosurgery 19:405–407, 1986 spurius) following laminectomy. Report of ten cases. J Bone 17. Hadley MN, Carter LP: Sacral fracture with pseudomenin- Joint Surg Am 50:268–276, 1968 gocele and cerebrospinal fluid fistula: case report and review of 40. Nash CL Jr, Kaufman B, Frankel VH: Postsurgical meningeal the literature. Neurosurgery 16:843–846, 1985 pseudocysts of the lumbar spine. Clin Orthop 74:167–178, 18. Hawk MW, Kim KD. Review of spinal pseudomeningoceles 1971 and cerebrospinal fluid fistulas. Neurosurg Focus 9 (1):Article 41. Naso WB, Cure J, Cuddy BG: Retropharyngeal pseudomenin- 5, 2000 gocele after atlanto-occipital dislocation: report of two cases. 19. Hanakita J, Kinuta Y, Suzuki T: Spinal cord compression due to Neurosurgery 40:1288–1291, 1997 postoperative cervical pseudomeningocele. Neurosurgery 17: 42. O’Connor D, Maskery N, Griffiths WE: Pseudomeningocele 317–319, 1985 nerve root entrapment after lumbar discectomy. Spine 23: 20. Helle TL, Conley FK: Postoperative cervical pseudomeningo- 1501–1502, 1998 cele as a cause of delayed myelopathy. Neurosurgery 9: 43. Oppel F, Schramm J, Schirmer M, et al: Results and complicat- 314–316, 1981 ed course after surgery for lumbar disc herniation. Adv Neuro- 21. Hofstetter KR, Bjelland JC, Patton DD, et al: Detection of bron- surg 4:36–51, 1977 chopleural-subarachnoid fistula by radionuclide myelography: 44. Osaka K, Handa H, Watanabe H: Traumatic intrathoracic case report. J Nucl Med 18:981–983, 1977 meningocele (traumatic subarachnoid-pleural fistula). Surg 22. Hosono N, Yonenobu K, Ono K: Postoperative cervical Neurol 15:137–140, 1981 pseudomeningocele with herniation of the spinal cord. Spine 45. Pagni CA, Cassinari V, Bernasconi V: Meningocele spurius fol- 20:2147–2150, 1995 lowing hemilaminectomy in a case of lumbar discal hernia. J 23. Johnson JP, Lane JM: Traumatic lumbar pseudomeningocele Neurosurg 18:709–710, 1961 occurring with spina bifida occulta. J Spinal Disord 11:80–83, 46. Patel MR, Louie W, Rachlin J. Postoperative cerebrospinal 1998 fluid leaks of the lumbosacral spine: management with percuta- 24. Jones AA, Stambough JL, Balderston RA, et al: Long-term neous fibrin glue. AJNR 17:495–500, 1996

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47. Pau A: Postoperative “meningocele spurius.” Report of two 58. Teplick JG, Peyster RG, Teplick SK, et al: CT identification of cases. J Neurosurg Sci 18:150–152, 1974 postlaminectomy pseudomeningocele. AJR 140:1203–1206, 48. Pomeranz S, Constantini S, Umansky F: The use of fibrin 1983 sealant in cerebrospinal fluid leakage. Neurochirurgia 34: 59. Thakur RC, Khosla VK, Kak VK: Non-missile penetrating 166–169, 1991 injuries of the spine. Acta Neurochir 113:144–148, 1991 49. Pyeritz RE: The Marfan syndrome. Am Fam Physician 34: 60. Tsuji H, Handa N, Handa O, et al: Postlaminectomy ossified 83–94, 1986 extradural pseudocyst. Case report. J Neurosurg 73:785–787, 50. Reisinger PW, Hochstrasser K: The diagnosis of CSF fistulae 1990 on the basis of detection of beta 2-transferrin by polyacrylamide 61. Waisman M, Schweppe Y: Postoperative cerebrospinal fluid gel electrophoresis and immunoblotting. J Clin Chem Clin leakage after lumbar spine operations. Conservative treatment. Biochem 27:169–172, 1989 Spine 16:52–53, 1991 51. Rinaldi I, Hodges TO: Iatrogenic lumbar meningocele: report of 62. Wilkinson HA: Nerve-root entrapment in “traumatic” extradu- three cases. J Neurol Neurosurg Psychiatry 33:484–492, ral arachnoid cyst. J Bone Joint Surg Am 53:163–166, 1971 1970 63. Zide BM, Epstein FJ, Wisoff J: Optimal wound closure after 52. Rosenberg PH, Heavner JE: In vitro study of the effect of epi- tethered cord corrections. Technical note. J Neurosurg 74: dural blood patch on leakage through a dural puncture. Anesth 673–676, 1991 Analg 64:501–504, 1985 64. Zide BM, Wisoff JH, Epstein FJ: Closure of extensive and com- 53. Rosenblum DJ, Derow JR: Spinal extradural cysts: with report plicated laminectomy wounds. Operative technique. J Neuro- of an ossified spinal extradural cyst. AJR 90:1227–1230, 1963 surg 67:59–64, 1987 54. Schumacher HW, Wassmann H, Podlinski C: Pseudomenin- 65. Zilkha A, Reiss J, Shulman K, et al: Traumatic subarachnoid- gocele of the lumbar spine. Surg Neurol 29: 77–78, 1988 mediastinal fistula. Case report. J Neurosurg 32:473–475, 55. Shahinfar AH, Schechter MM: Traumatic extradural cysts of 1970 the spine. AJR 98:713–719, 1966 56. Shapiro SA, Scully T: Closed continuous drainage of cere- brospinal fluid via a lumbar subarachnoid catheter for treatment or prevention of cranial/spinal cerebrospinal fluid fistula. Neu- rosurgery 30:241–245, 1992 Manuscript received September 1, 2003. 57. Smith MD, Bolesta MJ, Leventhal M, et al: Postoperative cere- Accepted in final form September 22, 2003. brospinal-fluid fistula associated with erosion of the dura. Address reprint requests to: Charles L. Branch, Jr., M.D., Findings after anterior resection of ossification of the posterior Department of Neurosurgery Wake Forest University School of longitudinal ligament in the cervical spine. J Bone Joint Surg Medicine, Winston-Salem, North Carolina 27157-1029. email: Am 74:270–277, 1992 [email protected].

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