Spinal intramedullary arachnoid cyst: case report and literature review.

BACKGROUND CONTEXT: Intramedullary arachnoid cysts are extremely rare; only 14 cases have been reported in the literature so far. PURPOSE: We report on the case of a 31-year-old woman who presented with back pain and progressive paraparesis secondary to a dorsal intramedullary arachnoid cyst detected on magnetic resonance imaging (MRI): the surgical planning and clinico-radiological outcome are discussed along with a review of the relevant literature. STUDY DESIGN: Case report and literature review. PATIENT SAMPLE: One patient affected by intramedullary arachnoid cyst. OUTCOME MEASURES: Magnetic resonance imaging and pathological findings from operative specimens were used to confirm the diagnosis. METHODS: A 31-year-old woman presented with a 7-year history of back pain that had worsened 3 months before admission to our department; for this reason, the patient had undergone a spinal MRI revealing the presence of a 1-cm cystic intramedullary lesion at the level T11-T12, with no contrast enhancement. After 2 months, the patient presented with a worsening of clinical symptoms complaining of severe back pain radiating to the lower extremities associated with a progressive paraparesis, urinary incontinence, and abdominal pain. Referred to our department, at the time of admission the patient was bedridden because of the impossibility of maintaining a standing position. The patient underwent a T11-T12 laminectomy with fenestration of the cyst. RESULTS: She experienced an immediate relief of pain symptoms, and by the seventh postoperative day she was able to stand without help and walk a few meters with assistance. By the sixth postoperative month, the patient had significantly improved, having gained the ability to walk alone without assistance with complete resolution of the bladder dysfunctions, with no cyst recurrence after approximately 2 years of follow-up. CONCLUSIONS: Intramedullary arachnoid cysts should be considered in the differential diagnosis for intramedullary cystic lesions. A particular consideration deserves their occurrence in asymptomatic patients, who should be adequately informed on the possible natural evolution: when symptomatic, surgical therapy should be promptly offered, considering that a postoperative complete recovery is usually observed, regardless of the surgical technique.