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.
This 21-year-old man complained of worsening radiating pain and hypesthesia on left leg for 1 year. His motor weakness was grade 4 on left leg, especially when extending the left ankle. Because of worsening symptoms he eventually visited our department. He had mild claudication, positive on left straight leg raising test at 45 degree. We confirmed a mild left S1 radiculopathy on electromyography. He had no neurologic deficit associated with cauda equina syndrome. Preoperative MR imaging showed a 20×13×14 mm sized sacral cyst (). We performed myelogram and CT and found the contrast-filled stalk between the thecal sac and the cyst. The cyst compressed a contiguous structure including nerve roots ().\nWe performed surgery the same as patient 1 () and symptoms disappeared after one week. Follow up MR imaging after 2 months demonstrated complete resolution of the lesion. We checked with MR imaging after 1 year and ascertained that there was no further cystic formation and complication ().