Stiff person syndrome

Stiff person syndrome

Description, Causes and Risk Factors:

Alternative Name: Moersch-Woltmann syndrome, Stiff man syndrome (SMS).

Alternative Name: SPS.

Stiff man syndrome is a rare disorder of the central nervous system (CNS) characterized by progressive rigidity and painful intermittent spasm. The muscle spasm stiffness starts insidiously in the axial and proximal musculature, with a steady, slow progression over months or years. Muscle spasms are early complains and may dominate the clinical presentation. These are often precipitated by tactile or emotional stimuli. These are often precipitated by tactile or emotional stimuli.

The exact prevalence of SPS is unknown; it is a rare condition. It affects more females than males, and the age of onset is in the third to sixth decade of life.

The etiology of the disease is unknown, although ?-aminobutyric acid or gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter in brain and spinal interneurons. GABAergic pathways serve as one of the types of inhibitory pathways by which spinal interneurons coordinate motor function by inhibiting spontaneous discharges from spinal motor neurons. Impairment of the GABAergic pathways with deficiencies in brain GABA leads to continuous firing of the spinal motor neurons, with resultant stiffness and spasms which are the hallmark of SPS. The association of SMS with diseases such as diabetes, vitiligo and hypothyroidism, and the detection of autoantibodies against (?-aminobutyric acid) GABA-ergic neurons in serum and cerebrospinal fluid (CSF) suggest that the disease has an autoimmune nature.


General symptoms may include:

    Muscle stiffness in the trunk and limbs that comes and goes--this causes back stiffness or pain, an exaggerated upright posture, and stiff-legged walk.

  • Severe muscle spasms in the arms and legs when the person is startled, touched, upset, or anxious.

  • Curved lower back (lordosis) and deformed joints in the body, over time.

  • Falling during sudden muscle spasms (may cause additional related problems).

Autonomic Symptoms:


  • Pupil dilation.

  • Tachycardia.

  • Tachypnea.

  • Hyperthermia.

  • Hypertension.


The disorder is often misdiagnosed as Parkinson's disease, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia.

The diagnosis ismade, after exclusion of other known pathologies, primarilyon clinical criteria of stiffness, predominantly in axialmuscles, with co-contraction of agonist and antagonistmuscles and paroxysmal spasms. The diagnosis is supportedby investigations including neurophysiological examination,which demonstrates spontaneous motor unit activity at restsimultaneously from agonist and antagonist muscles, andimmunological examination, which reveals high serum andCSF titres of anti-GAD antibodies. In addition to theseantibodies, antiamphiphysin antibodies1 antigephyrin andanti-Ri antibodies2 are often found in paraneoplastic stiffperson syndrome.

Immunological study may show:

    Anti Glutamic Acid Decarboxylase.

  • Positive in serum and CSF in 60%.

  • Ab to pancreatic islet cells in 60%.

  • Ab to gastric parietal cells in 50%.

  • Ab to microsomes in 30-40%.

  • Ab to thyroglobulin in 15%.

  • Oligoclonal Ig G in CSF in 30%.

Electromyography is a very important diagnostictool and reveals continuous motor unit activity simultaneously in agonist and antagonist muscles. This motoractivity is abolished by diazepam, sleep, or generalanesthesia.


Pharmacological treatment may include:

    Benzodiazepines and other GABA-acting medications remain essential to managing the stiffness and spasms of SPS. Risk and benefits must be discussed with the physician.

  • Diazepam is also widely used as standard symptomatic treatment.

  • Baclofen and other anticonvulsant drug are less frequently effective.

  • Combination may be helpful to decrease risk of addiction and side effects.

Other Treatment Options May Include:

Treatments may also include immune-modulating therapies such as IVIG (intravenous immunoglobulin) and plasmapheresis, patient and staff education, behavioral and physical therapy.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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