As autonomous practitioners the ability to perform differential diagnosis is more important than ever. Proper differential diagnosis is the difference between treating an impairment versus treating the cause of a patient's problem. It is the difference between decreasing a patient's pain today and eliminating their movement dysfunction forever. Part of this process should include assessing the joints above or below the region of dysfunction. In this post, I want to pose this question:
How do you determine if a patient is having ulnar nerve adverse neural tension or a movement dysfunction consistent with C8-T1 radiculopathy?
On initial examination, both diagnoses will have a similar presentation. In both scenarios the patient may have positive upper extremity neural tension tests, weakness and/or muscle atrophy of the hand intrinsic muscles, pain along the ulnar nerve distribution, and potentially cervical segmental nerve dysfunction. How do you differentiate? Two key features that will distinguish the difference between the peripheral nerve tension and C8-T1 radiculopathy are 1. test the strength of the extensor pollicis longus (EPL) and 2. perform specific sensation testing of the affected upper extremity.
While the EPL muscle arises from the C8 nerve root (similar to ulnar nerve), it is innervated by the posterior interosseous nerve (a branch of the radial nerve). If the EPL muscle is intact, the C8 nerve root must be functioning normally. Therefore, the dysfunction is most likely a peripheral ulnar nerve entrapment. If the nerve root is the region of compromise all muscles, not only those innervated by the ulnar nerve, will be affected. The second method of assessment is checking the pattern of sensory loss. Ulnar nerve sensory loss affects the medial one and a half digits. Contrarily, the C8 nerve root can have pain from the lower scapula down the posteromedial aspect of the arm into the ring and little finger.
The differences may seem subtle, but if a practitioner only suspects ulnar nerve tension, they are neglecting the cervical spine. As part of your differential diagnose make sure to assess the joint above and below the dysfunction.
Now who remembers how to MMT the EPL...