neurologic disorders
Isaacs Syndrome
Diagnosis of Isaacs Syndrome
Clinical evaluation Results of nerve conduction and EMG studies The diagnosis of Isaacs syndrome is based on the above clinical findings and results of nerve conduction and EMG studies, which show characteristic abnormalities; these abnormalities include after-discharges on nerve conduction studies and, on needle EMG studies, fasciculation potentials, myokymic discharges, neuromyotonic discharges, fibrillation potentials, and cramp discharges, most prominent in distal limb muscles. Laboratory testing should include tests for antibodies to contactin-associated protein-like 2 (Caspr2), the striational voltage-gated calcium channel, gliadin, glutamic acid decarboxylase (GAD), muscle acetylcholine receptor (AChR), and the voltage-gated potassium channel. About 20% of patients with Caspr2 antibodies have thymoma or other solid tumors, which may be diagnosed by chest CT or MRI. 