Neurol Med Chir (Tokyo) 51, 867¿871, 2011

Surgical Treatment of Sacral Perineural —Case Report—

Hiroaki MATSUMOTO,1 Shigeo MATSUMOTO,1 Takanori MIKI,1 Yuki MIYAJI,1 Hiroaki MINAMI,1 Atsushi MASUDA,1 Shogo TOMINAGA,1 Yasuhisa YOSHIDA,1 Ikuya YAMAURA,1 Shigeatsu NATSUME,1 and Kozo YOSHIDA1

1Department of Neurosurgery, Eisyokai Yoshida Hospital, Kobe, Hyogo

Abstract A 67-year-old man presented with persistent penis and scrotum pain due to S-2 and S-3 caused by a sacral perineural cyst. The cyst was treated with microsurgical partial cyst removal and cyst wall imbrication, together with closure of the point through which (CSF) flowed from the subarachnoid space into the cyst cavity. His pain resolved without recurrence of the cyst or complications. Symptomatic perineural are quite rare. Surgical closure of the point through which CSF flows from the subarachnoid space into the cyst cavity is the most important intervention for symptomatic perineural cysts. If the source of CSF leakage cannot be detected, placement of a cyst- subarachnoid shunt should be considered in addition to partial cyst removal and cyst wall imbrication. Key words: perineural cyst, spine , Tarlov cyst, , microsurgery

Introduction both lower extremities. Sensations of light touch, pin- prick, proprioceptive stimuli, and vibration were intact. Perineural cysts are lesions of the nerve roots most often Neither urinary nor fecal incontinence was noted. Mag- found in the sacral region, which were first described in netic resonance (MR) imaging revealed a 25 × 15-mm cys- autopsy studies of the filum terminale.17) Perineural cysts tic lesion in the sacrum isointense with the cerebrospinal arise at the junction of the dorsal ganglion and posterior fluid (CSF) (Fig. 1A, B). The cyst was on the right side at S2 nerve root, and develop between the endoneurium and level and compressed the right S-2 and S-3 nerve roots perineurium, most commonly at the S2 or S3 level.17,18) The toward the wall of the canal (Fig. 1C–E). Computed prevalence has been reported as approximately 1.5% to tomography (CT) myelography demonstrated delayed fill- 4.6% in the general adult population.6,13) Although most ing of the cyst, indicating communication between the perineural cysts are asymptomatic, approximately 1% cyst and the arachnoid space (Fig. 1F, G). cause symptoms related to local compression.13) Only sym- Our diagnosis was penis and scrotum pain due to S-2 ptomatic perineural cysts should be treated surgically. and S-3 nerve root radiculopathy caused by a sacral However, no consensus exists regarding the appropriate perineural cyst. Microsurgical treatment was performed. surgical procedures.2,3,16,18) The cyst was exposed via an S2 laminectomy. The cyst We describe a case of sacral perineural cyst treated suc- wall appeared tough and tense (Fig. 2A). To avoid nerve cessfully with microsurgical partial cyst removal and cyst and venous plexus injury, dissection of the cyst from the wall imbrication, together with closure of the communica- surrounding structures was not performed. After fenestra- tion between the cyst and the arachnoid space with ab- tion of the cyst wall, clear CSF-like fluid was found, which sorbable collagen sponge and fibrin glue. was evacuated with suction, and the cyst wall was then partially removed. The right S-2 nerve root ran caudally Case Report along the inner surface of the cyst wall (Fig. 2B). There was a dural tear in the vicinity of the S-2 nerve root sleeve. A 67-year-old man had been suffering from progressive pe- Pulsatile CSF flow passed out through the dural tear, but nis and scrotum pain for 3 years. Although he had been the reverse phenomenon did not occur. To close the com- treated at the urology department for a long time, his pain munication between the subarachnoid space and the cyst, had not improved. He rated the pain as 7 of 10 on the the dural tear was closed with absorbable collagen sponge visual analog scale (VAS). The pain was neither exacerbat- and fibrin glue (Fig. 2C). After the repair, no further in- ed by changes of the posture nor relieved by recumbence. flow of CSF was observed. Imbrication of the cyst wall Muscle strength and deep tendon reflexes were normal in was performed using 6–0 nylon (Fig. 2D). Histological examination revealed that the cyst walls Received December 27, 2010; Accepted May 2, 2011 mostly consisted of dense, fibrocollagenous bundles with

867 868 H. Matsumoto et al.

bance, motor deficits, neurogenic claudication, bowel and bladder dysfunction, or sexual impotence.1–19) Specific radicular pain may be the result of distortion, compres- sion, or stretching of the nerve root by the space-occup- ying features of cysts. Symptoms can be exacerbated by changes in posture, coughing, Valsalva maneuvers, stand- ing, lifting, and climbing stairs, all of which increase CSF pressure. The symptoms can be relieved by recumbence. These phenomena can be explained by the ball-valve mechanism.3,5,11,12) In our case, although the pain was neither exacerbated by movements which increase the CSF pressure nor relieved by recumbence, we diagnosed S-2 and S-3 nerve root radiculopathy caused by a sacral perineural cyst, because MR imaging had revealed the perineural cyst at the S2 level affecting the right S-2 and S-3 nerve roots without lumbar or sacral lesions. Consensus has been achieved that asymptomatic perineural cysts should be followed up. However, whether patients with symptomatic perineural cysts should be treated surgically remains under discussion.2,3,16,18) In fact, the majority of symptomatic perineural cysts have been treated surgically, but conservative treatment with steroid or gabapentin has been reported.8,9) Successful surgical treatment of perineural cysts depends on appropriate patient selection.11,16,18) Several predictors of an effective operative outcome have been proposed, including large cysts greater than 15 mm in diameter, delayed filling of the cyst on CT myelography, and radicular pain or bowel/bladder dysfunction.11,16,18) The curable symptoms

Fig. 1 Preoperative investigations. A, B: Sagittal T1-weight- are , dyspareunia, sacral pain, and perianal 16) ed (A) and T2-weighted (B) magnetic resonance images demon- pain. On the other hand, and vogue lumbago are strating a 25 × 15-mm cystic lesion at the S2 level, and the cyst residual symptoms. In our case, preoperative investiga- contents isointense with the cerebrospinal fluid. C: Axial T1- tions revealed the cyst was 25 × 15 mm in size, and weighted magnetic resonance image demonstrating the cyst delayed filling of the cyst was observed on CT my- compressing the right S-2 nerve (arrow) toward the wall of the elography. Moreover, the cyst caused S-2 and S-3 nerve canal. D, E: Coronal T -weighted magnetic resonance images 1 radicular pain. Therefore, a good operative outcome was demonstrating the cyst (asterisk) compressing both the right S-2 expected, and surgical treatment was performed. nerve root (D: arrow) and the right S-3 nerve root (E: arrow). F, G: Computed tomography myelograms at the S2 level immedi- Several surgical procedures for perineural cysts have 1–7,10–16,18,19) ately (E) and 3 hours (F) after intrathecal injection showing been reported, but no consensus exists of the delayed filling of contrast medium. most appropriate. The procedures are of three types: procedures to lower CSF hydrostatic and pulsatile pres- sures, such as external CSF drainage1) or lumbar sparse cellularity, with no nervous tissue identified (Fig. peritoneal shunt1); procedures to decompress cysts, such 3). The histological diagnosis was perineural cyst. as simple decompressive laminectomy,15) CT-guided per- Postoperatively, he rated his pain at 3 of 10 on the VAS im- cutaneous aspiration,7,13) or cyst-subarachnoid shunt5,10); mediately after the operation. He was discharged without and direct surgical procedures such as bipolar cautery to complications or pain (0 of 10 on the VAS) on postopera- shrink cysts,14) total cyst removal,2,12) partial cyst removal tive Day 10. Postoperative MR imaging revealed collapse with neck ligation,4,18) or cyst wall imbrication.3,6,11,16,19) of the cyst and the decompressed right S-2 and S-3 nerve These surgical options are summarized in Table 1. Each roots (Fig. 4). He experienced neither pain nor recurrence procedure has some advantages and disadvantages. Re- of the cyst at the 12-month follow-up examination. cently, simple decompressive laminectomy and CT-guided percutaneous aspiration have not been recommended, be- Discussion cause of the relatively high rates of complication and low- er rates of success.2,3,18) Asymptomatic perineural cysts or Tarlov cysts are gener- The goals of surgical treatment are to relieve neural ally found coincidentally when lumbar MR imaging or CT compression and prevent recurrence and CSF leakage. is performed for other reasons, whereas symptomatic The former is achieved by decompressing the cysts, and perineural cysts are quite rare.6,13) Depending on the loca- the latter by repair of defects or closure of communica- tion, size, and relationship to the nerve roots, perineural tions between the cyst and arachnoid space. Microsurgi- cysts may cause local or radicular pain, sensory distur- cal partial cyst removal and cyst wall imbrication with

Neurol Med Chir (Tokyo) 51, December, 2011 Sacral Perineural Cyst 869

Fig. 2 Intraoperative photographs (upper row) and corresponding illustrations (lower row) showing the surgical steps and findings. A: After S2 laminectomy, the cyst (arrowheads) was exposed. B: After fenestration of the cyst wall and evacuation of the fluid, the right S-2 nerve root ran caudally along inner the surface of the cyst wall (asterisk). Pulsatile cerebrospinal fluid flow was observed through the right S-2 nerve root sleeve (arrow). C: The dural tear was closed with absorbable hemostat and fibrin glue. D: The cyst wall was imbricated with 6–0 nylon. Arrows indicate the closure line.

procedures,11) but excision or ligation of cysts together with the involved nerve roots should be avoided, since such injury often results in neurological deficits, even if with monitoring confirmation that no major component of the nerve root enters the cyst.2,3) Bipolar cautery to shrink cysts may also be hazardous because of the possibility of nerve injury. On the other hand, cyst-subarachnoid shunt- ing may be an effective option, since continuous CSF ex- cretion can reduce the volume of cysts and prevent regrowth. The possibilities of dysfunction and infection Fig. 3 Photomicrographs showing the cyst wall consisting of dense, fibrocollagenous bundles with sparse cellularity, with should always be considered when performing this proce- 1–3) no identified nervous tissue. Hematoxylin and eosin stain, dure. original magnification A: ×40, B: ×200. In our case, the strategy of surgical treatment was both to decompress the cyst and to close the communication be- tween the cyst and the arachnoid space completely, since defect repair are frequently recommended.2,3,6,11,16,19) This CT myelography demonstrated delayed filling of the cyst. procedure may be the most reasonable, since the goals of We consider that detection and closure of the point where treatment can be achieved without venous and nerve inju- CSF flows from the subarachnoid space into the cyst cavi- ry. Total cyst removal or partial cyst removal with neck li- ty is most important. Therefore, we chose to perform gation may also be useful. However, nerve injury is possi- microsurgical treatment first; if we had not been able to lo- ble during dissection of the entire cyst or neck ligation, be- cate the source of leakage of CSF, a cyst-subarachnoid cause the sacral nerve root runs from the cyst neck along shunt would have been required in addition to partial cyst the medial cyst wall.2,3) Electrophysiological monitoring removal and cyst wall imbrication. However, we were may help minimize injury to sacral nerve roots during able to detect and close the point of CSF leakage, so partial

Neurol Med Chir (Tokyo) 51, December, 2011 870 H. Matsumoto et al. cyst removal and cyst wall imbrication were performed tion during the follow-up period ranging from 1 month to without shunt placement. 73 months. Our patient experienced immediate resolution A total of 32 cases of sacral perineural cysts treated with of pain without complication or recurrence of the cyst at partial cyst removal and cyst wall imbrication have been 12-month follow up, but recurrence is possible, because a reported, including the present case (Table 2).3,7,11,16,19) part of the cyst remained. Twenty-seven of the 32 patients experienced complete or We recommend microsurgical partial cyst removal and substantial resolution of their symptoms. Five patients had cyst wall imbrication together with closure of the point no significant improvement. Four patients suffered through which CSF flows from the subarachnoid space postoperative complications such as bladder dysfunction, into the cyst cavity for symptomatic perineural cysts. If CSF leak, prostatitis, and cerebellar bleeding. Only one the source of CSF leakage cannot be detected, placement patient had recurrence of the cyst and underwent reopera- of a cyst-subarachnoid shunt should be considered in addi- tion to partial cyst removal and cyst wall imbrication.

References

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Table 1 Summary of surgical procedures for perineural cysts

Procedure Advantage Disadvantage 1. Procedures to lower the hydrostatic and pulsatile pressures 1–1. External CSF drainage ease high recurrence rate 1–2. Lumboperitoneal shunt ease possibilities of dysfunction and infection 2. Procedures to decompress the cysts 2–1. Simple decompressive laminectomy ease low success rate 2–2. CT-guided percutaneous aspiration ease high recurrence rate and complications such as meningitis, nerve injury, and hemorrhage into the cyst 2–3. Cyst-subarachnoid shunt ease possibilities of dysfunction and infection 3. Direct surgical procedures 3–1. Bipolar cautery to shrink the cysts ease possibility of nerve injury 3–2. Total cyst resection complete cure possibilities of nerve injury and CSF leakage 3–3. Partial cyst removal and neck ligation complete cure possibility of nerve injury 3–4. Partial cyst removal and cyst wall imbrication complete cure possibility of CSF leakage

CSF: cerebrospinal fluid, CT: computed tomography.

Neurol Med Chir (Tokyo) 51, December, 2011 Sacral Perineural Cyst 871

Table 2 Summary of reported cases of sacral perineural cysts treated with partial cyst removal and cyst wall imbrication

No. of Age Sex Complica- Recur- Follow up Author (Year) patients (yrs) (M/F) Repair materials Improved tions rence (mos)

Yucesoy et al. 1 48 0/1 FG and cementation 1/1 no no 3 (1999)19) Mummaneni et al. 8 34–72 2/6 FG and fat or muscle 7/8 no no 1–73 (2000)11) Lee et al. (2004)7) 2 24–46 0/2 none 2/2 no no 6–12 Tanaka et al. 9 43–72 6/3 none 7/9 2/9 no 6–24 (2006)16) Guo et al. (2007)3) 11 28–44 6/5 FG, absorbable 9/11 2/9 1/11 28–44 gelatin sponge, and muscle Present case 1 67 1/0 FG and absorbable 1/1 no no 12 collagen sponge

FG: fibrin glue.

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