Stiff-man syndrome

Stiff-person syndrome (SPS), also known as stiff-man syndrome, is a rare neurological disorder of unclear cause characterized by progressive muscular rigidity and stiffness. The stiffness primarily affects the truncal muscles and is characterised by spasms, resulting in postural deformities. Chronic pain, impaired mobility, and lumbar hyperlordosis are common symptoms. SPS occurs in about one in a million people and is most commonly found in middle-aged people. A small minority of patients have the paraneoplastic variety of the condition. Variants of the condition, such as stiff-limb syndrome, which primarily affects a specific limb, are often seen. SPS was first described in 1956. Diagnostic criteria were proposed in the 1960s and refined two decades later. In the 1990s and 2000s, the role of antibodies in the condition became clearer. SPS patients generally have glutamic acid decarboxylase (GAD) antibodies, which seldom occur in the general population. In addition to blood tests for GAD, electromyography tests can help confirm the condition's presence. Benzodiazepine-class drugs are the most common treatment; they are used for symptom relief from stiffness. Other common treatments include baclofen, intravenous immunoglobin, and rituximab. Limited but encouraging therapeutic experience of haematopoietic stem cell transplantation exists for SPS.