Epiconus Syndrome and Conus Syndrome

The most caudal part of the spinal cord shows special anatomical characteristics and it contains epiconus (L4-S2 segments), the conus medullaris (S3-S5 segments), and surrounding nerve roots. Lesions of the thoracolumbar junction cause epiconus or conus syndrome. Epiconus syndrome is characterized by segmental muscular weakness and atrophy of one or both lower extremities, often accompanied by foot drop. It may manifest as motor neuron disease in the absence of sensory loss. Ossification of the ligamentum flavum is an important cause of epiconus syndrome. Conus syndrome is characterized by urinary and rectal disturbances, usually accompanied by some motor and sensory symptoms involving the lower extremities. Both syndromes are often misdiagnosed as lumbar radiculopathy or cauda equina lesions. A thorough understanding of the anatomical features and pathophysiology is important for early and accurate diagnosis of epiconus or conus syndrome.