Table 1

Main features of stiff-person syndrome

Diagnostic criteria*
Major criteria Stiffness in the axial and limb muscles, prominently in the abdominal and thoracolumbar paraspinal muscles leading to a fixed deformity (hyperlordosis) Superimposed painful spasms precipitated by unexpected noises, emotional stress, or tactile stimuli EMG: confirmation of continuous motor unit activity in agonist and antagonist muscles. Absence of other neurological disorders or cognitive impairment that could explain the stiffness Minor criteria Positive anti-GAD65 (or antiamphiphysin) antibodies in serum, assessed by immunocytochemistry, Western blot or radioimmunoassay Clinical response to benzodiazepines†

Diagnostic criteria*

Major criteria

Stiffness in the axial and limb muscles, prominently in the abdominal and thoracolumbar paraspinal muscles leading to a fixed deformity (hyperlordosis)
Superimposed painful spasms precipitated by unexpected noises, emotional stress, or tactile stimuli
EMG: confirmation of continuous motor unit activity in agonist and antagonist muscles.
Absence of other neurological disorders or cognitive impairment that could explain the stiffness Minor criteria
Positive anti-GAD65 (or antiamphiphysin) antibodies in serum, assessed by immunocytochemistry, Western blot or radioimmunoassay
Clinical response to benzodiazepines†

Subtypes of stiff-person syndrome
I Classic stiff-person syndrome II Stiff person variants Focal or segmental stiff-person syndrome Jerky stiff-person syndrome PERM Stiff-person syndrome plus (ataxia, epilepsy, etc) Paraneoplastic stiff-person syndrome

Associated autoimmune disorders	Associated neoplasia
Diabetes mellitus type 1	Breast cancer‡
Hashimoto's thyroiditis	Pulmonary cancer
Grave's disease	Renal cell carcinoma
Pernicious anemia	Thyroid carcinoma
Anti-NMDAR encephalitis	Colon cancer
Limbic encephalitis	Neuroendocrine neoplasm
Refractory epilepsy	Thymoma
Polyendocrine autoimmune syndrome	Hodgkin lymphoma
Vitiligo	Non-Hodgkin lymphoma
Caeliac disease	Cholangiocarcinoma
Myasthenia gravis
Autoimmune retinopathy and scleritis
Systemic lupus erythematosus
Major complications
Severe dysautonomic and painful muscle spasms crises
Oesophageal obstruction from cricopharyngeal muscle spasm
Hypoxemic respiratory failure
Falls
Fractures and joint dislocations
Sudden death

Anti-NMDAR, anti-N-methyl-D-aspartate receptor; EMG, electromyography; GAD, glutamic acid decarboxylase; PERM, progressive encephalomyelitis with rigidity and myoclonus.
*According to Dalakas MC 2009.
†Considered in some cases.
‡Usually associated with antiamphyphisin antibodies.