Sudden, Severe Upper Limb Pain and Weakness in a Sleepless Man

Olusegun John Oluwole, MBBS

Disclosures

December 14, 2020

Discussion

Cervical spine degenerative disease with C5-C6 root compression can most certainly present with a clinical picture similar to this patient's, with weakness in muscles innervated by the fifth and sixth cervical roots, such as the supraspinatus, infraspinatus, deltoid, and biceps muscles. However, neck pain is usually a prominent complaint in addition to arm pain in such circumstances, and a cervical spine MRI scan would typically show obvious disk or bony spurs compressing on the involved nerve root at its exit foramen.[1]

Rotator cuff syndrome also shares clinical similarities with brachial neuritis.[2] In fact, many patients with brachial neuritis are thought initially to have rotator cuff disorder and often undergo repeated shoulder scans before the correct diagnosis is made. This patient had two normal shoulder MRI results before brachial neuritis was finally diagnosed. Not surprisingly, cases have been reported of patients who were subjected to orthopedic surgical interventions, sometimes more than once, before the correct diagnosis was made.[3] Despite the similarities between rotator cuff syndrome and brachial neuritis, striking clinical differences are recognized and can assist the clinician in distinguishing the conditions on clinical grounds. The shoulder is usually tender to palpation in rotator cuff syndrome, and shoulder range of motion is typically limited by pain and by some degree of impingement during passive movement.[4] In addition, sensory loss over the deltoid area and rapidly progressive wasting of the shoulder muscles is highly unlikely in rotator cuff syndrome.

Monomelic amyotrophy, also known as Hirayama disease, is an interesting disease of the anterior horn cells of the cervical spinal cord, which manifests with insidious unilateral upper limb muscle wasting with or without associated fasciculations.[5] Hirayama disease often causes anxiety for patients and clinicians because of its clinical resemblance to the early stages of amyotrophic lateral sclerosis. However, it is unusual for this condition to be heralded by pain, and the clinical course is less rapid than that of brachial neuritis.[5]

Although this patient has signs consistent with distal sensory polyneuropathy and carpal tunnel syndrome, such as loss of pinprick sensation in a stocking distribution and bilaterally positive Phalen test results, respectively,[6] these two conditions do not cause shoulder pain or weakness. Hence, an alternative explanation was sought.

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