Elbow Neurological Conditions

Disorders of the central nervous system, of the cervical spinal nerves, or of the major peripheral nerves of the upper limb may present with features that include pain in the elbow, but they rarely, if ever, do they present with pain in the elbow as the only feature. Major disorders such as cervical radiculopathy, complex regional pain syndrome, and peripheral neuropathy will present with pain over a region greater than or other than the elbow, and with neurological symptoms and signs such as numbness, weakness, dysaesthesia or allodynia. The presence of such features converts the presentation from one of simply elbow pain to one of a neurological disorder. Under those conditions, the patient should be managed according to guidelines for neurological disorders; not according to the present guidelines which pertain explicitly to elbow pain.

Neurological conditions that may be specifically related to the elbow are radial tunnel syndrome, posterior interosseous nerve entrapment, ulnar neuropathy, and painful neuroma.

RADIAL TUNNEL SYNDROME

It has been argued that lateral elbow pain can result from entrapment of the radial nerve in the radial tunnel as it passes through the arcade of Fröhse in the supinator muscle1. This afflication has been advanced as a cause of refractory tennis elbow^2,3. However, detracting views argue that there is little evidence to support this belief.Van Rossum et al⁴ studied 10 sequential patients with refractory lateral epicondylitis. Detailed EMG studies were performed, and distal motor latencies of the radial nerve innervated muscles were measured. No evidence of radial nerve compression was found. In a similar study, Verhaar and Spaans⁵ found only one of 16 patients with nerve conduction abnormalities. Thus, the objective evidence is inconsistent with the proposed basis of this syndrome.Further evidence against the concept of radial tunnel syndrome stems from surgical experience with the procedures. One study reported experience with 37 consecutive cases who underwent radial tunnel release⁶. Only 13 patients obtained substantial relief; only 16 returned to work; complications were encountered in 12. The authors concluded that the diagnostic criteria for this condition were unreliable.The other study followed two groups of patients. The study retrospectively considered two groups of patients7. The first group had a decompression procedure of the tarsal tunnel for suspected radial tunnel syndrome; the second had lengthening of the extensor carpi radialis brevis on the basis of suspicion of lateral epicondylitis. The first and perhaps most interesting observation is that there was no significant difference in the clinical features of the two groups in terms of site of tenderness, tenderness over the radial nerve of the forearm and superficial radial nerve paraesthesiae. The second observation of note is that, despite the similarity in their presentation, both groups did just as well at operation. A detailed consideration of the effects of the operations revealed that the operation directed at the epicondyle would have no effect on the radial tunnel , but the converse effect was not true. The radial tunnel operation was demonstrated to effectively release the common extensor origin. Therefore, it is argued that the improvement in what was probably a homogenous group of patients was achieved by release of the extensor tendon and not the decompression of the radial tunnel.

POSTERIOR INTEROSSEOUS NERVE ENTRAPMENT

Posterior interosseous nerve entrapment is a syndrome that should be readily differentiated from a non-neurological lesion at the elbow by simple virtue of the fact that there is weakness of wrist extension and weakness in finger extension as primary manifestations^8,9.

ULNAR NEUROPATHY

Patients with compression of the ulnar nerve are described as presenting with pain and aching over the medial elbow and proximal forearm. This is invariably accompanied by neurological abnormalities, principally tingling and paraesthesiae over the 4^th and 5^th fingers of the hand¹⁰. The wider distribution of pain than that seen in uncomplicated medial epicondylitis, and the association with neurological symptoms should make differentiation of ulnar nerve compression from medial epicondylitis relatively straightforward.

NEUROMA

Small nerves may be injured anywhere in the body, and if regeneration is imperfect, a painful neuroma may result. The distinctive clinical features will be a history of surgery or nerve injury, associated with pain of a stabbing or shooting quality, with point tenderness over the course of the affected nerve, palpation of which triggers the pain. If the nerve has been substantially injured there will be loss of sensation in the territory innervated by the sensory fibres of the nerve, and loss of function of any muscles innervated by the nerve if it contains motor fibres. Any nerve that crosses the elbow might be so affected.

Any nerve that crosses the elbow might be so affected. Accordingly, physicians such be alerted to the possibility of painful neuroma in patients who present with a history of possible nerve injury, with stabbing pain, and with point tenderness over the course of a small nerve.

On the grounds that neuroma formation is not a musculoskeletal condition, its management is not covered by these guidelines. Nevertheless, it is a condition that should be recognized if encountered. Options for management lie with neurosurgeons, plastic surgeons, or pain clinics.

REFERENCES

1. Rath AM, Perez M, Mainguene C, Masquelet AC, Chevrel JP. Anatomic basis of the physiopathology of the epicondylalgias: a study of the deep branch of the radial nerve. Surg.Radiol.Anat. 1993; 15:15-19.
2. Noteboom T, Cruver R, Keller J, Kellogg B, Nitz AJ. Tennis elbow: a review. J.Orthop.Sports Phys.Ther. 1994; 19:357-366.
3. Gellman H. Tennis elbow (lateral epicondylitis). Orthop.Clin.North Am. 1992; 23:75-82.
4. van Rossum J, Buruma OJ, Kamphuisen HA, Onvlee GJ. Tennis elbow--a radial tunnel syndrome? J.Bone Joint Surg.Br. 1978; 60-B:197-198.
5. Heyse Moore GH. Resistant tennis elbow. J.Hand Surg.Br. 1984; 9:64-66.
6. Verhaar J, Spaans F. Radial tunnel syndrome: an investigation of compression neuropathy as a possible cause. J Bone Joint Surg 1991; 73A:539-544.
7. Atroshi I, Johnsson R, Ornstein E. Radial tunnel release. Unpredictable outcome in 37 consecutive cases with a 1-5 year follow-up. Acta Orthop Scand 1995; 66:255-257.
8. Plancher KD, Peterson RK, Steichen JB. Compressive neuropathies and tendinopathies in the athletic elbow and wrist. Clin.Sports Med. 1996; 15:331-371.
9. Kleinert JM, Mehta S. Radial nerve entrapment. Orthop.Clin.North Am. 1996; 27:305-315.
10. Khoo D, Carmichael SW, Spinner RJ. Ulnar nerve anatomy and compression. Orthop.Clin.North Am. 1996; 27:317-338.