The Stiff Man (or Stiff Person) Syndrome is a heterogenous disorder associated with involuntary muscle stiffness or spasms. It is believed to be an autoimmune disorder involving the central nervous system and resulting in impairment of the neuronal pathways.
Patients affected: both men and women, usually with an insidious onset during the fourth or fifth decade.
Types based on underlying diseases:
(1) associated with an underlying autoimmune disease
(2) paraneoplastic
(3) idiopathic
Features:
(1) Intermittent muscle rigidity/stiffness and spasms, usually symmetric.
(2) A stereotypic motor pattern during attacks may occur.
(3) The presence of autoantibodies.
(4) Lack of neurological signs.
Muscle rigidity/stiffness and spasms
(1) These occur most often in the back but may involve muscles in the abdomen, extremities, head and neck.
(2) EMG studies may be nonspecific but often show continuous motor unit activity in the affected muscles.
(3) Hyperlordosis of the lumbar spine may be produced by contraction of thoracolumbar paraspinal and abdominal wall muscles
(4) Episodes may be spontaneous or they may be precipitated by sudden or loud noises, sudden movements, anxiety, strong emotions, and/or sudden jarring.
(5) The spasms may be painful.
(6) Late changes include gait abnormalities, a restricted range of motion and slowness of movement.
Interventions that can reduce or stop an attack:
(1) Both rigidity and spasms stop during sleep or anesthesia.
(2) Myoneural or peripheral nerve blockade may stop attacks.
(3) Intravenous or oral diazepam may result in a significant improvement in symptoms, which may be a diagnostic finding.
(4) Corticosteroids with or without plasmapheresis may result in significant clinical improvement.
The stereotyped motor pattern may include opisthotonos, stiffness of slightly abducted legs and inversion of the plantar fixed feet.
Autoantibodies, which may be present in both serum and CSF
(1) anti-GAD antibodies
(2) antibodies to islet cells
(3) antithyroid antibodies
(4) antigastric antibodies
(5) anti-GABA-ergic neurons
(6) antibodies to amphiphysin (a protein in synaptic vesicles, found in the paraneoplastic syndrome)
(7) antibodies to 125/130 kd protein (found in the paraneoplastic syndrome)
Other findings:
(1) Some patients experience an aura-like feeling prior to spasmodic attacks.
(2) Some patients show a phobia to crossing open spaces unaided.
(3) Elevated immunoglobulins and increased lymphocytes may be found in the CSF.
(4) Epilepsy may occur in about 10% of patients.
(5) Insulin-dependent diabetes mellitus is relatively common.
Purpose: To evaluate a patient for findings associated with the Stiff Man (or Stiff Person) Syndrome.
Specialty: Immunology/Rheumatology
Objective: clinical diagnosis, including family history for genetics, laboratory tests, criteria for diagnosis
ICD-10: G25.82,
