A 47-year-old woman presented with a complaint of severe headache of sudden onset. On neurological examination, she had signs of meningeal irritation. Brain computed tomography (CT) revealed Fisher grade 3 SAH. Three-dimensional brain CT angiography showed an anterior communicating artery aneurysm. Emergent craniotomy and neck clipping of the aneurysm were performed.\nIn the early postoperative period, she complained of pain mainly on the right side of the sacrum, buttock, and upper part of the posterior aspect of the right thigh. She complained of worsening pain when sitting down, walking, or coughing. She had a previous history of lumbago 3 years ago and it was relieved with conservative treatment. CT of the lumbosacral spine performed at that time revealed a bulging disc at the L4-L5 level and a PC at the S2 level (Fig. A). Thereafter, she did not have lumbago and there was no history of recent trauma. The nature and location of her pain were slightly different from the nature and location of pain she had experienced 3 years ago. During this episode, sacral and buttock pain was more severe than lumbago. She complained of severe tingling sensation and right-side predominant pain. The pain did not subside fully when lying down. She suffered from the pain despite using analgesics for 4 weeks.\nMagnetic resonance imaging (MRI) of the lumbosacral spine performed at 1 month postoperatively showed an 18×13×25 mm-sized PC with high signal intensity (SI) at the S2 level affecting the right S2 root and a so-called dark’ and bulging disc at multiple levels of the lumbosacral spine on the T2-weighted sagittal image (Fig. B). On the nonenhance T1-weighted sagittal image, mixed high and low SI with a fluid–fluid level within the cyst, suggestive of intracystic hemorrhage, was revealed (Fig. C). There is a perineural cyst that is located to the right aspect at S2 level (Fig. D). The size of the cyst measured on MRI showed no apparent enlargement of the cyst compared with the size on the CT performed 3 years ago.\nIt seemed that the size of the cyst had not increased as compared with the size of the cyst on the CT performed 3 years ago. An electrodiagnostic study was performed 6 weeks after the onset of the pain, and it showed subacute right S2 radiculopathy. There were abnormal findings such as delayed onset latency of the right bulbocavernosus response, spontaneous denervation activity, and fibrillations in the right side of the anal sphincter muscle, soleus muscle and foot intrinsic muscles (abductor digiti minimi, abductor halluces). The fibrillation potentials had increased amplitude of 300uV, which suggested that 6 weeks to 3 months had elapsed after denervation.[\nWith conservative treatment, her pain gradually diminished. Follow-up MRI performed 3 months later showed no change in the size of the PC. However, mixed SI and a fluid–fluid level within the PC disappeared on the enhanced T1-weighted sagittal image (Fig. E). As this is a case report, ethical approval was not required. Informed patient consent was obtained for the publication of this report.
A 40-year-old male presented with a 3-year history of sensory changes involving the S2–S3 distribution in the right leg (e.g., hypoesthesia without motor weakness or dysuria). The lumbosacral MRI showed a noncontrast enhancing right-sided cystic mass at the S2–S3 level; it had the same intensity as CSF on both the T1- and T2-weighted images []. Coronal fat-suppressed T2-weighted images revealed the mass likely originated from the right S3 nerve root and was additionally compressing the right S2 nerve root [].\nA laminoplastic laminotomy was performed at three levels using an ultrasonic bone curette. At surgery, the S3 nerve root was enveloped within cyst wall and the S2 nerve root was clearly compressed [Figure and ]. Partial resection of the cyst wall and imbrication of residual tissue was performed []. An inlet from the subarachnoid space was identified, and its obliteration was confirmed by a Valsalva maneuver []. This subarachnoid connection was sealed with adipose tissue and fibrin glue []. Plication of the cyst wall was performed with nonpenetrating titanium clips (Vascular Clip System; LeMaitre Vascular Inc., Burlington, MA) []. No postoperative CSF leakage occurred, and spinal lumbar drainage was not warranted. The patient's preoperative sensory disturbance resolved. The postoperative MRI showed a reduction in the cyst's size [Figure and ] and no residual compression of the S2 nerve root []. Histopathological examination confirmed collagen connective tissue without nerve fibers, findings consistent with a Tarlov cyst []. The patient remained asymptomatic 6 months later, and the 6-month postoperative sacral MRI demonstrated no cyst recurrence.