Spasm of the near reflex mimicking myasthenia gravis.

Spasm of the near reflex and myasthenia gravis both may present as isolated abduction deficits, either unilaterally or bilaterally. Although they each have been mistaken for other more serious causes of neurologic dysfunction, convergence spasm has not been reported previously as mimicking myasthenia gravis. Two cases of convergence spasm were diagnosed initially as myasthenia gravis with positive Tensilon tests. The cases emphasize the need to consider convergence spasm in the diagnosis of any patient with isolated abduction deficits, as well as to suggest that double-blinded Tensilon tests may be unnecessary and possibly misleading.