Terminal extramedullary conus spinal cord lipoma

Terminal extramedullary conus spinal cord lipoma is a rare congenital spinal dysraphism characterized by a lipomatous (fatty) mass located at the terminal end of the spinal cord (conus medullaris) but situated outside the medullary tissue itself. Unlike intradural lipomas that infiltrate the substance of the spinal cord, this type of lipoma is attached to the terminal conus or filum terminale without significant invasion into the neural tissue. It is classified among closed spinal dysraphisms (occult spinal dysraphisms), meaning the overlying skin is typically intact, though cutaneous stigmata such as a subcutaneous lipoma, skin dimple, or hairy patch may be present over the lower back. This condition primarily affects the nervous system, specifically the lumbosacral spinal cord and associated nerve roots. The lipoma can cause tethering of the spinal cord, restricting its normal movement within the spinal canal. As a child grows, this tethering may lead to progressive neurological symptoms including lower extremity weakness, gait abnormalities, sensory changes in the legs and perineal region, back or leg pain, and bladder or bowel dysfunction (neurogenic bladder or bowel). Orthopedic manifestations such as foot deformities (e.g., pes cavus, equinovarus) or scoliosis may also develop. Symptoms may present in infancy or childhood, though some patients remain asymptomatic until later in life. Diagnosis is typically made through magnetic resonance imaging (MRI) of the spine, which can delineate the lipoma and its relationship to the conus medullaris and surrounding neural structures. Management depends on the presence and severity of symptoms. Surgical intervention, usually involving untethering of the spinal cord and debulking of the lipoma, is considered when neurological deterioration is evident or anticipated. The goal of surgery is to prevent further neurological decline rather than to reverse existing deficits. Prophylactic surgery in asymptomatic patients remains a topic of clinical debate. Long-term urological and neurological follow-up is recommended, as retethering can occur after surgical intervention.

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