UMN lesions can cause positive or negative symptoms. If the symptoms are negative, they are shown as weakness in a muscle group. Positive symptoms are due to an increase in muscle activation.
Findings for positive symptoms are as follows: spasticity in a muscle group, clonus, hyper-reflexion when testing reflexes of the arms or legs, or aberrant movements on tests such as the Babinski test. The Babinski test involves stroking the sole of the foot firmly, and if the toes slowly extend rather than quickly flex/ pull away from the tester, this is a sign of a possible UMN issue. Several tests exist as part of the clinical repertoire for testing the UMNs, but the Babinksi Test is one of the most common.
This study investigated the validity and reliability of the Babinski test with three groups of participants: 1) individuals with cortical lesions that had been identified with clinical testing and imaging; 2) those with neurological illnesses that did not impact the cortex; and 3) normal, healthy individuals.
Each group comprised 125 participants. The groups were tested with the Babinski test, but also with the toe tapping and finger tapping tests. The toe and finger tapping tests were designed to test rapid and small motor movements of the participants – as fine motor movement becomes impaired in people with known UMN lesions.