Timothy C. Hain, MD
Page last modified: June 18, 2009
Motor neuron diseases include disorders such as ALS (Amyotrophic Lateral Sclerosis). In general, these disorders are dominated by progressive weakness, muscle wasting, and respiratory compromise. Occasionally, however, they are also accompanied by abnormal eye movements. There is no literature that supports a mechanism of damage to motor neurons in cranial nerve nuclei. Rather, the few report cases document persons with both motor neuron disease and either basal ganglia or cerebellar disease. These patients overlap with progressive supranuclear palsy and multiple system atrophy, which are two uncommon central nervous system degenerations associated with abnormal accumulation of tau neurofibrillary protein.
We are very dubious that motor neuron disease causes eye movement disorders. Rather, we think it in some cases, motor neuron diseases are associated with multisystem neurological diseases. Sharma has recently reviewed this area (2011).
Averbuch-Heller and others reported 2 patients with ALS and slow vertical saccades. Autopsy showed cell loss in the RIMLF and substantia nigra. Okuda, Yamamoto, et al. (1992) reported 2 patients with slow saccades and a supranuclear vertical gaze palsy. Autopsy in one patient revealed degeneration of the substantia nigra. The ALS-Parkinson-Dementia complex is a well known group of patients in Guam who combine features of ALS, and progressive supranuclear palsy.
Overall, there seems to be evidence for rare combinations of vertical supranuclear gaze palsy and ALS.
Kushner et al (1984) reported 2 patients with ALS and gaze evoked rotatory nystagmus. As gaze-evoked rotatory nystagmus is a variant of normal, the significance of this is uncertain.
Manabe, Y., Y. Shiro, et al. (2000) reported a single case of cerebellar ataxia followed by motor neuron disease. This presentation is suggestive of multiple system atrophy.