Electrophysiologic evaluation of upper motor neuron involvement in amyotrophic lateral sclerosis.
BACKGROUND
The demonstration of upper motor neuron (UMN) dysfunction in patients with amyotrophic lateral sclerosis (ALS) with predominantly lower motor neuron (LMN) signs is clinically sometimes difficult.


METHODS
We analyzed the possible role of F and H waves in the diagnosis of UMN dysfunction in 36 patients with different clinical forms of ALS and 20 controls. In both lower limbs we evaluated F-wave persistence and the F/M ratio of tibial nerves, Hmax/Mmax ratio, vibratory and recurrent (paired) inhibition of the H-reflex.


RESULTS
The persistence of the F-response was decreased significantly in the LMN group only. The F/M amplitude ratio, vibrated-H/rest-H amplitude ratio and conditioned H/rest H amplitude ratio were significantly increased in patients with predominantly UMN, as well as in those with predominantly LMN signs. H/M amplitude ratios did not differ between the various patient groups.


CONCLUSIONS
These findings show that ALS patients, including those without clinical evidence of UMN involvement, have a marked disinhibition of anterior horn motor neurons. The simple tests described could support an UMN abnormality when clinical signs are lacking, and help to establish a diagnosis sooner and more accurately.
Drory
V E
VE
Department of Neurology, ALS Clinic, Sourasky Medical Center, Tel Aviv, Israel. emgunit@tasmc.health.gov.il
Kovach
I
I
Groozman
G B
GB
D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology*; D004594:Electrophysiology; D005260:Female; D006181:H-Reflex / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000473:pathology*