Quantification of hyperreflexia in amyotrophic lateral sclerosis (ALS) by the soleus stretch reflex

The aim of this study was to quantify upper motor neuron (UMN) involvement in amyotrophic lateral sclerosis (ALS) by the soleus stretch reflex.

In a group of 24 ALS patients and ten healthy controls the soleus stretch reflex was elicited by a four degree rotation at the ankle joint. Amplitude of the short-latency stretch reflex, threshold, and sensitivity were determined. Peripheral excitation/contraction properties were evaluated by supramaximal stimulation of the tibial nerve. Clinical scores of upper motor neuron involvement were applied.

A highly significant correlation between threshold and sensitivity of the stretch reflex and clinical score of upper motor neuron involvement was found; patients with a low threshold and a high sensitivity in general had a high upper motor neuron score.

It is suggested that upper motor neuron involvement in ALS can be evaluated by using the soleus stretch reflex. This may be useful in monitoring progression of the disease and evaluating new therapies.