The Social Security Administration established the Compassionate Allowances program in an attempt to expedite cases where individuals have medical conditions that are very severe and would qualify under one of the listings. However, not all diseases are met under a specific listing, but still may be approved under the CAL.
Stiff Person Syndrome (SPS) is a rare disease of the nervous system. Progressively severe muscle stiffness typically develops in the spine and lower extremities; often beginning very subtly during a period of emotional stress. Most patients experience painful episodic muscle spasms that are triggered by sudden stimuli. Clinically, stiff person syndrome is characterized by muscle rigidity that waxes and wanes with concurrent spasms. Treatment with IVIg, anti-anxiety drugs, muscle relaxants, anti-convulsants, and pain relievers will improve the symptoms of SPS, but will not cure the disorder. Most individuals with SPS have frequent falls and because they lack the normal defensive reflexes; injuries can be severe.
Social Security recommends that in order for Stiff Person Syndrome to be properly evaluated an EMG and special anti-body testing should be performed, as well as a clinical history and examination that describes the diagnostic features of the impairment, progression of neurological symptoms, response to medication, and evaluative tests that rule out other causes of stiffness.
Stiff person disease medically equals Listing 11.04B under Central nervous system vascular accident, and 11.06 Parkinsonian Syndrome.
 Duddy ME, Baker MR. Stiff person syndrome. Front Neurol Neurosci. 2009;26:147-65