Given that my doctoral training is in neuroscience, I am always delighted when some neurological condition turns up in a book. For a detective series written by a non-scientist, the
Cormoran Strike books have been an amazingly rich source, with
phantom limb syndrome, BIID, and even a brief mention of Capgras syndrome. So it was exciting to see that Brown-Séquard syndrome was featured in The Ink Black Heart. But how accurate is it? Does it alone account for the symptoms Josh Blay has? And how do you wind up paralyzed on one side and without feeling on the other, anyway?
First, yes,
Brown-Séquard syndrome is a thing, though is is very rare, happening in less that 4% of all spinal cord injuries. It was first described by
Charles Éduoard Brown-Séquard in 1850. Brown-Sequard, a figured well-known in my own sub-field of hormones and behavior, had highs and lows in his career. He is often remembered for some now-discredited self-experiments he performed late in life, claiming that an extract from animal testicles that he self-administered increased his physical strength, mental acuity and the length of his urine stream. However, he would
perhaps be more fairly remembered for two earlier contributions. First, his work with the adrenal glands provided some of the first evidence for the existence of hormones: a tremendously important discovery that help launch the field of endocrinology. Second, his research on spinal cord anatomy showed that different modalities are carried by different tracts in the cord, and led to the description of the syndrome that now bears his name.
Brown-Séquard syndrome produces its odd collection of symptoms because it involves a hemisection of the spinal cord: in other words, a cut through half of it. The first thing to understand is that different parts of the cord carry different sensory and motor signals. Fibers that carry
motor commands from brain to muscle travel in the
lateral corticospinal tract (see blue on picture to the left). Fibers that carry
pain and temperature signals from skin to brain travel in the
spinothalamic tract (red). And fibers that carry information about
vibration, pressure and limb position (which is very important for reaching for objects, walking, etc) are carried in the
posterior column (green).