A 46-year-old man presents with numbness in his distal fingertips. The patient rarely seeks medical attention and has an insignificant past medical and family history. The patient reports drinking 6 to 7 beers per week and smoking a half pack of cigarettes per day. During neurologic examination, the patient is asked to extend his arms with his eyes shut and maintain his palms facing up. During this maneuver, the patient’s arms both pronate.
Based on the above finding, which of the following is impaired in this patient?
A. ProprioceptionUpper motor neuron pathway. This patient is exhibiting pronator drift on neurologic examination. This is both a specific and sensitive test for upper motor neuron (UMN) disease. UMN disease will very often cause a weakness in supination that allows the pronating muscles to become more dominant. Therefore, when patients are asked to close their eyes and stretch out their arms with their palms facing upward, the affected arm(s) will pronate.
(A) Proprioception can be assessed in various physical examination maneuvers. One of the more common ways to evaluate proprioception is with the Romberg test in which the patient stands with his or her feet together and the practitioner observes if the patient is able to maintain balance with their eyes closed. Patients with impaired proprioception will lose their balance. (C) Although this patient presents with “numbness,” which might lead the reader to the false conclusion that he has peripheral neuropathy leading to impaired tactile sensation (measured by pinprick discrimination), this maneuver was not explicated in the question. (D) Cerebellar function is responsible for balance and coordination and can be assessed by testing for rapidly alternating movements.