Dissociated sensory loss (cape distribution)

What it is

Dissociated sensory loss is a pattern in which a person loses the sensation of pain and temperature while the sensation of light touch is relatively preserved. In syringomyelia, this loss classically occurs over the shoulders and arms — a "cape-like" or "shawl" distribution.

Understanding Dissociated sensory loss (cape distribution)

Pain and temperature sensations travel along nerve fibers that cross through the central part of the spinal cord, near the central canal — exactly where a syrinx tends to form. As the syrinx interrupts these crossing fibers, the sensations of pain and temperature are lost, while the fibers carrying light touch (which travel in a different part of the cord) are relatively spared — producing the "dissociated" pattern. Because a Chiari-associated syrinx is usually in the cervical cord, this loss often appears over the shoulders, upper back, and arms, in a cape-like distribution. This characteristic pattern can be an important clue to syringomyelia. Understanding dissociated sensory loss clarifies a hallmark sensory feature of syringomyelia and why it follows this distinctive pattern.

Why it matters

Understanding dissociated sensory loss helps families recognize a hallmark feature of syringomyelia — loss of pain and temperature sensation in a cape-like distribution — that can be an important clue to a syrinx.