Stiff man syndrome

Stiff man syndrome is a rare disease of the CNS characterized by fluctuating rigidity and muscle spasms. Patients get the rigidity when they get simultaneous contraction of agonist and antagonist muscles- when this happens, they become stiff and can actually topple over like a wooden man. Patients get painful muscle spasms that are precipitated by noise, voluntary movement, and even fear! Stiff man syndrome is thought to be an autoimmune disease for a number of different reasons: (1) there's a genetic association between the incidence of disease and the HLA complex, (2) patients develop antibodies against neurons that secrete the inhibitory neurotransmitter GABA. These antibodies are typically against GAD, which is the enzyme that makes GABA. Intriguingly enough, 10% of stiff man syndrome patients have epilepsy, which is higher than normal. A loss of GABA signaling has been shown in epilepsy, providing further evidence that in stiff man syndrome, there's a directed attack on GABAergic neurons.

So if you have stiff man syndrome, what's the treatment? Well, typically patients are given diazepam, which potentiates the effect of endogenously released GABA on GABA receptors. If patients don't respond to diazepam, then often other GABA affecting drugs are given.

Cool, huh?