What is syringomyelia?

• A. Degeneration of dorsal columns
• B. CSF builds up in central canal
• C. CSF accumulates in lateral ventricles
• D. Peripheral nerve entrapment

Answer: (B)

Syringomyelia is the formation of a fluid-filled cavity, or syrinx, inside the spinal cord. This syrinx is typically connected to or formed from the spinal cord’s central canal, so CSF accumulates within the cord itself. As the cavity enlarges, it first disrupts the crossing fibers of the spinothalamic tract at the anterior white commissure, producing a loss of pain and temperature sensation in a cape-like distribution over the shoulders and arms, while light touch and vibration remain intact. Over time, the expanding syrinx can affect the anterior horn cells, leading to weakness and muscle wasting at the level of the syrinx, and in children it can contribute to scoliosis. Additional context includes associations with Chiari malformation or prior spinal injury, which can impair CSF dynamics and facilitate syrinx formation.

The best description among the options is that CSF builds up in the central canal, forming a CSF-filled cavity within the spinal cord. The other choices describe degeneration of dorsal columns (not the hallmark of syringomyelia), CSF accumulation in the lateral ventricles (hydrocephalus), or peripheral nerve entrapment (a peripheral nerve problem), none of which capture the spinal cord cavity pathology of syringomyelia.