Patients with paraneoplastic SPS generally lack other autoimmune issues but may have other paraneoplastic conditions.Stiff-limb syndrome is a variant of SPS. This syndrome develops into full SPS about 25% of the time. Stiffness and spasms are usually limited to the legs and hyperlordoisis generally does not occur. The stiffness begins in one limb and remains most prominent there. Sphincter and brainstem issues often occur with stiff-limb syndrome. Progressive encephalomyelitis with rigidity, another variant of the condition, includes symptoms of SPS with brainstem issues and autonomic disturbances. It involves polio-encephalomyelitis in the spine and brainstem. There is cerebellar and brainstem involvement. In some cases, the limbic system is affected, as well. Most patients have upper motoneuron issues and autonomic disturbances. Jerking SPS is another subtype of the condition. It begins like classical SPS and progresses for several years; up to 14 in some cases. It is then distinguished by the development of myoclonus as well as seizures and ataxia in some cases. Causes
Patients with SPS generally have high amounts of high glutamic acid decarboxylase antibody titers. About 80 percent of SPS patients have GAD antibodies, compared with about one percent of the general population. The overwhelming majority of people who have GAD antibodies do not contract SPS, indicating that systematic synthesis of the antibody is not the sole cause of SPS. GAD, a presynaptic autoantigen, is generally thought to play a key role in the condition, but exact details of the way that autoantibodies affect SPS patients are not known.
Ravulizumab, sold under the brand name Ultomiris, is a humanized monoclonal antibody complement inhibitor medication designed for the treatment of paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome. It is designed to bind to and prevent the activation of Complement component 5 (C5).Paroxysmal nocturnal hemoglobinuria is characterized by red blood cell destruction, anemia (red blood cells unable to carry enough oxygen to tissues), blood clots, and impaired bone marrow function (not making enough blood cells). In paroxysmal nocturnal hemoglobinuria, proteins known as the complement system, which is part of the immune system, become overactive because of a genetic mutation and start to attack the patients own red blood cells. Ravulizumab, is a monoclonal antibody (a type of protein) designed to attach to the C5 protein, which is part of the complement system. By attaching to the C5 protein, the medicine blocks its effect and thereby reduces the destruction of red blood cells.The most common side effects are upper respiratory tract infection (nose and throat infection), nasopharyngitis (inflammation of the nose and throat) and headache. The most serious side effect is meningococcal infection, a bacterial infection caused by Neisseria meningitidis that can cause meningitis and sepsis.