NeurometPlus

Incidence

Transmitted as an autosomal recessive trait. Some cases are familial; parental consanguinity was noted in a few instances.

Clinical Characteristics

Schwartz-Jampel syndrome is an autosomal recessive disorder characterized by hypertrophied muscles and myotony. Myotony can be triggered by percussion and leads to a peculiar facies that associates blepharophimosis with a stiff expression. Other clinical signs include small stature, hirsutism, myopia and small testes. It is a syndrome of short stature; generalized myotonia with contractures of major joints, microstomia, and muscle rigidity; ocular anomalies, mainly blepharophimosis; and characteristic facies marked by pinched or frozen smile puckered lips. Some degree of mental retardation occurs in about 25% of patients. The affected children usually appear normal at birth and the symptoms become recognizable at 1 to 3 years of age. Malignant hyperthermia is a potentially lethal hazard during anesthesia. Electromyographic investigations reveal repetitive muscle discharges which may originate from both neurogenic and myogenic alterations. Schwarts-Jampel syndrome may be suspected in neonates with Kniest-like chondrodysplasia, congenital bowing of shortened femora and tibiae, and facial manifestations consisting of a small mouth, micrognathia, and possibly pursed lips. The disorder must be differentiated from the Stuve-Wiedemann syndrome, a genetically distinct myotonic chondrodysplasia with similar clinical but different skeletal changes and an unfavorable early prognosis. Myotony is difficult to treat. Some authors have reported that carbamazepine improved patients\' condition. Mutations, including missense and splicing mutations, of the gene encoding perlecan (HSPG2) have been found in three families.

Precipitants

Anesthesia complications include difficult intubation secondary to microstomia and risk of malignant hyperthermia.

Provocation Tests

No

Diagnostic Procedures

It is a clinical diagnosis.