Objective and importance: The ventriculus terminalis of the conus, or "fifth ventricle" refers to the ependymal-lined space in the middle of the conus that is present in childhood and whose persistence into adulthood is rare. A number of cases of cystic dilatation of the ventriculus terminalis have been described in adulthood. Patients tend to present with either pain alone or gradually progressive conus or cauda equina syndromes with varying degrees of recovery after cyst drainage. Presentation with an acute cauda equina syndrome and its successful surgical management has not been previously reported.
Clinical presentation: A 57-year-old woman experienced back pain and bilateral sciatica ascribed to diabetic neuropathy for 2 years. Over a 24-hour period she developed bilateral lower extremity weakness, saddle anesthesia, and bowel and bladder incontinence. Lumbosacral magnetic resonance imaging demonstrated a large cystic dilatation of the ventriculus terminalis.
Intervention: She was taken for emergency surgical decompression and cyst drainage. Immediately after surgery, she experienced significant increase in lower extremity strength and has since regained continence.
Conclusion: Cystic dilation of the ventriculus terminalis should be part of the differential diagnosis for a cauda equina syndrome; surgical decompression with simple cyst drainage can result in excellent clinical results.