The etiology of SS is currently not well characterized, but its association with other autoimmune diseases such as myasthenia gravis, systemic lupus erythematosus (SLE), and immune thrombocytopenic purpura (ITP) and the presence of antinuclear antibodies (ANA) in around half of patients has led to the postulate that it is autoimmune in nature. No genetic association has been identified.
SS most commonly presents in childhood; however, approximately 25% of patients do not experience symptoms until adulthood, with a range of onset from age 1-52 years. Women are more commonly affected than men, with a ratio of 3:1. Most reported cases are in Japan, but sporadic cases have been documented worldwide.
Muscle spasms are present in all reported cases of SS and are the initial symptom in most. Onset is in childhood or adolescence. Initially, the lower extremities are affected with intermittent painful spasms that last seconds to minutes and occur several times daily. As the disease progresses, spasms become more severe and involve other muscle groups (ie, trunk, upper extremities, respiratory muscles, face muscles). Spasms are exacerbated during use of the affected muscle groups and by decreased temperature and emotional stress.
Skeletal abnormalities are present in approximately 85% of SS patients with pediatric-onset disease and are not typically seen in adult-onset disease. Osseous changes are secondary to repeated damage to tendon attachment sites, epiphyses, and growth plate by chronic muscle spasms. This repetitive damage results in osteolytic lesions and bony deformities that cause a decreased range of motion in the affected joints.
Alopecia is present in most cases. It typically presents as rapidly progressive loss of all scalp hair (alopecia totalis; AT) or all scalp and body hair (alopecia universalis; AU) over the course of weeks to months. Hair loss may also present as diffuse scalp hair thinning that does not progress to AT or AU. AT and AU are more common in patients with ANA positivity. The mean age of onset in pediatric patients is 10 years. The mean age of onset in adult patients is 28 years. Alopecia and muscle spasms often present concurrently in adult patients.
Chronic, episodic diarrhea that may be accompanied by abdominal pain, nausea, or vomiting is present in most patients. The mean age of onset for diarrhea is 15 years. Episodes of diarrhea are exacerbated by a high-carbohydrate diet. While the severity of diarrhea can range from mild to severe, with malabsorption (ie, malnutrition, growth retardation, iron deficiency anemia, hypoproteinemia, secondary amenorrhea), most patients do have abnormal D-xylose testing (indicating carbohydrate malabsorption).
M35.89 – Other specified systemic involvement of connective tissue
763630007 – Satoyoshi syndrome
- McArdle disease
- Isaacs syndrome
- Myokymia of Kny and Schultze
- Schwartz-Jampel syndrome (permanent muscle stiffness and chondrodysplasia)
- Stiff person syndrome
- Paramyoclonus multiplex of Friedreich
- Myotonic dystrophy
- Hypothyroid myopathy
- Cartilage hair hypoplasia (dwarfism, hypotrichosis, and immune deficiency)
- Rickets-alopecia syndrome (type IIA vitamin D-dependent rickets)