What Is Stiff Person Syndrome (SPS)?

Stiff Person Syndrome (SPS) is a rare autoimmune movement disorder that affects the central nervous system and is clinically characterized by muscle stiffness, spasms, and increased inhalation responses to unexpected stimuli (involuntary defensive responses).

People with stiff person syndrome (SPS) have progressive stiffness of the trunk muscles (trunk muscles), which become stiff and tight as the lower back and abdominal muscles continue to contract. Stiffness leads to postural changes and the patient has a stiff gait. Over time, the patient’s legs and other muscles can become stiff and rigid.

As the disease progresses, stiffness in the muscles of the legs develops, which is more often expressed on one side than on the other (asymmetric). This condition tenses the leg muscles over time, followed by other muscles such as the arms and even the face.

The disorder can progress as it affects the hands and other parts of the body. It is believed that the chained person syndrome is part of a wide range of similar diseases that affect one area of ​​the body and then spread throughout the body.

Symptoms can appear at any age, but usually appear between the ages of 30 and 60. The entire course of SPS, from symptom onset to death, ranges from 6 to 28 years. The severity and progression of SPS can vary from person to person.

SPS is characterized by intermittent stiffness of the muscles of the trunk and limbs and hypersensitivity to stimuli such as noise, touch, and emotional stress, which can cause muscle spasms. SPS belongs to the Rigid Personality Syndrome (RPSD) group of spectrum disorders that share the same clinical characteristics and the same spectrum of antibodies against neuronal proteins that are involved in the normal inhibition of central hyperexcitability, which explains its clinical characteristics. Stiffness syndrome (SPS) is a gradually progressive neuromuscular disorder in which autoimmune-mediated central nervous system (CNS) blockade of the inhibitory enzyme glutamine decarboxylase (GAD) causes progressive axial muscle stiffness.

SPS is an autoimmune disease that causes muscle stiffness, and spasms. Progressive encephalomyelitis with rigidity and myoclonus (PERM) is characterized by muscle stiffness and pain similar to those seen in individuals with classic rigidity syndrome. It occurs primarily in the abdominal and paraspinal muscles, causing stiffness, lumbar hyperlordosis, and postural instability. Stiffness mainly affects the muscles of the trunk and is superimposed by spasms, which leads to postural deformity.

Muscle spasms are often very painful and usually aggravate existing stiffness. Muscle stiffness fluctuates at first, sometimes for days or weeks, but over time begins to permanently impair mobility. Rigidity is due to the combined activation of agonist and antagonist muscles. Muscle stiffness usually begins insidiously in the lower back and legs and may mimic low back pain but tends to progress to other parts of the body over time, mainly to the distal limbs and abdominal muscles.

Later in SPS, you may experience increased muscle stiffness and stiffness. A feature associated with SPS is progressive and fluctuating muscle stiffness associated with muscle spasms. In addition to muscle stiffness, individuals with SPS also experience muscle spasms, which may occur for no apparent reason (spontaneous) or in response to various triggering events (eg, stimuli). Variations of this condition are often seen, such as limb stiffness syndrome, which primarily affects one specific limb.

Problems in GABA disruption, which likely causes the stiffness and spasms that are characteristic of SPS. The absence of GABA-dependent signals causes stiffness and stiffness of the trunk muscles and increases sensitivity to touch or noise. If GAD function is significantly suppressed, the GABA available for these functions is reduced and the muscles are continuously stimulated by motor neurons. It is believed that the immune system of people with stiffness syndrome mistakenly attacks the GAD enzyme, which reduces the amount of GABA in the body.

Other possible pathophysiological etiologies in patients deficient in GAD antibodies include postsynaptic components such as synaptophysin, amphotericin, gephyrin and GABA transaminases. From the initial description, more limited forms of SMS (sometimes paraneoplastic) have been reported, including “rigidity of the limbs” and “rigidity of the trunk” (usually in patients seronegative for GAD65 antibodies). Epilepsy and cerebellar ataxia, brainstem lesions, and myelopathy30 In addition, a rapidly progressive form with extensive involvement of the central nervous system called progressive encephalomyelitis with tonic and myoclonus (PERM) has been described. ). Incidence of SMS (classical form or its variants) or long-term response and outcome of treatment. Stiff limb syndrome or shapes associated with other neurological signs.

Rigid limb syndrome is characterized by localized involvement of a limb, usually the leg. Stiff limb syndrome can progress, affecting both legs and causing difficulty walking. In patients with stiff limb syndrome, the spasms overlap the stiffness of the legs and cause lameness or difficulty walking.

Some patients may present with myoclonus responsive to a prominent stimulus affecting the axial and proximal muscles of the limbs, known as the twitching stiff man syndrome. For most people with stiffness syndrome, the muscles in the trunk and abdomen are the first to become stiff and enlarged. In a minority of patients with SPS, breast, ovarian, or lung cancer presents paraneoplastically as proximal muscle stiffness. In addition to muscle rigidity, SPS is often accompanied by autonomic convulsions with profuse sweating, tachycardia, and arterial hypertension.

The diagnosis of SPS implies a primary indicator of suspicion based on recurring symptomatic manifestations, including axial muscle rigidity and overlapping episodic spasms. Criteria for the diagnosis of SPS were adopted in 1989 and included episodic axial stiffness, progression of stiffness, lordosis, and trigger spasms. After the patients’ symptoms shifted from muscle pain to increased stiffness and spasms, and in light of a repeat positive GAD65 antibody test, the diagnosis was changed to stiff person syndrome.

It is almost always associated with other autoimmune diseases, such as type 1 diabetes, thyroid disease, pernicious anemia, and vitiligo (Baizabal-Carvallo and Jankovic, 2015; Martinez-Hernandez et al., 2016). Rigid-body syndrome (SPS), originally known as rigid-body syndrome before its publication by Bloom and Jankovic in 1991, is characterized by increased axial and extremity muscle tone, overlapping muscle spasms resulting in lumbar lordosis and a rigid gait.

Diseases that should be differentiated from the stiffness syndrome include chronic tetanus, which is extremely rare; various types of dystonia and extrapyramidal diseases, easily excluded on the basis of a clinical examination; psychogenic illness; and neuromyotonia, a rare peripheral nerve disease characterized by painful pulsatile muscle spasms (which, unlike those seen in stiffness syndrome, persist after nerve block, anesthesia, and sleep and have typical electromyography findings). The disorder is characterized by stiffness, along with painful spasms.

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