Abstract
Tapping the radial side of the wrist normally elicits a reflex contraction producing elbow flexion, wrist extension and wrist radial deviation. An abnormal response, consisting of finger flexion when performing this manoeuvre is known as the inverted radial (supinator) reflex (IRR). The significance of this reflex in asymptomatic subjects is unknown.
To document the frequency of the IRR in an asymptomatic population and to identify any presymptomatic pathology in those subjects.
The study group consisted of patients and staff at the senior author's institution. Patients were taken from clinics where the complaints were of lower limb symptoms. Subjects were excluded if they had any history of neck pain or stiffness or if they had any subjectively abnormal sensation. The radial reflex was elicited with a tendon hammer. Those subjects with an IRR were asked to attend for a MRI scan of the cervical spine to investigate for any abnormality.
47 subjects were studied. There were 8 subjects who displayed an IRR. In 4 subjects the IRR was unilateral and in 4 bilateral. Seven subjects consented to further investigation by MRI. The average age of these patients was 36 years.
The MRI scans revealed normal appearances in 6 cases. There was no cord signal abnormality in any case.
The IRR occurred with a frequency of 17% in the study group. There was no significant cervical pathology identified in these subjects.
In young asymptomatic patients, the presence of an inverted radial reflex is of no diagnostic relevance.
