According to an article by MyClevelandClinic published on the 12th of march 2020, Stiff person syndrome is a rare autoimmune movement disorder that affects the central nervous system (the brain and spinal cord). Symptoms may include stiff muscles in the trunk (torso), arms, and legs; and greater sensitivity to noise, touch, and emotional distress, which can set off muscle spasms. Stiff person syndrome, formerly stiff man syndrome, can also cause painful muscle spasms. The muscle spasms occur randomly or can be triggered by noise, emotional distress and light physical touch. Stiff person syndrome is thought to be part of a wide range of similar diseases that involve one area of the body and then spread throughout the body. Stiff person syndrome is extremely rare. Only about 1 out of every 1 million people have been diagnosed this syndrome. Twice as many women have stiff person syndrome as men. Symptoms can occur at any age but usually develop between ages 30 and 60. If left untreated, SPS can potentially progress to cause difficulty walking and significantly impact a person’s ability to perform routine, daily tasks. Although the exact cause of SPS is unknown, it is believed to be an autoimmune disorder and sometimes occurs along with other autoimmune disorders such as diabetes, vitiligo, pernicious anemia, certain cancers, and many more
Forms of SFS
Jerking stiff-person syndrome
Jerking stiff-person syndrome is characterized by muscles stiffness and spasms usually affecting the legs. Affected individuals also develop involvement of the brainstem, which can cause myoclonus which is a general term used to describe the sudden, involuntary jerking of a muscle or group of muscles caused by muscle contractions. The twitching or jerking of muscles cannot be controlled by the person experiencing it.
Progressive encephalomyelitis
Progressive encephalomyelitis with rigidity and myoclonus (PERM) is characterized by stiffness and painful muscles that are similar to those seen in individuals with classic stiff-person syndrome. PERM is more rapidly progressive than other forms of SPS; onset of symptoms usually occurs over several weeks. Stiffness and spasms may occur along with, before or after the development of other symptoms including vertigo, a lack of coordination of voluntary muscles, and difficulty speaking. In some cases, the cranial nerves may also become involved causing paralysis of certain eye muscles, rapid, involuntary eye movements, difficulty swallowing, and hearing loss. PERM is considered a distinct disorder from classic SPS and some feel that it is a distinct condition all together.
Paraneoplastic-related stiff-person syndrome
Paraneoplastic-related stiff-person syndrome is a rare disorder that affects the nervous system in some individuals with cancer, especially individuals with cancer of the lungs or breast. The disorder is characterized by stiffness and rigidity, along with painful spasms. Symptoms usually begin in the muscles of the lower back and legs, although some individuals experience neck and upper torso symptoms first. The disorder may grow progressively worse eventually affecting the arms and other parts of the body. Painful muscle spasms can be worsened or triggered by a variety of events including anxiety, loud or unexpected noises or light physical contact.
Stiff-limb syndrome
Stiff-limb syndrome is characterized by the localized involvement of one limb, usually a leg. The stiffness and muscle spasms are extremely similar to those found in classic stiff-person syndrome. Stiff-limb syndrome may progress to eventually affect both legs and may cause difficulty walking. Some individuals may eventually develop classic stiff-person syndrome or variant SPS. When SPS affects only one specific area of the body, it may also be referred to as focal or partial stiff-person syndrome.
Diagnosing SPS
SPS is often misdiagnosed as Parkinson’s disease, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia. A definitive diagnosis can be made with a blood test that measures the level of glutamic acid decarboxylase (GAD) antibodies.
