Clumsy hands and funny bones: the cubital tunnel syndrome

Clumsy hands and funny bones: the cubital tunnel syndrome

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by Ray Jongs, Hand Physiotherapist

Nerves are wonderful things.

They have predominantly two roles: supplying sensation to an area so we can feel things, and supplying impulses to the muscles for movement.

If you have ever woken up in the middle of the night with tingling in your fingers, it is probably due to one of two major nerves in the arm: the median nerve at the wrist (carpal tunnel syndrome) or the ulnar nerve at the elbow (cubital tunnel syndrome).

Most people have heard of carpal tunnel syndrome, but due recognition should be paid to cubital tunnel syndrome. When the ulnar nerve is affected, sensation is altered to the little and ring finger, and the little muscles of the hand may become weaker (together with the wrist and finger flexors on the little finger side of the forearm). Interestingly, the thumb may be slightly affected as well; strength in pinch may be reduced, and the thumb feels less stable or dexterous.

Generally, physiotherapy will be assessing the ulnar nerve as it courses from the upper arm to the hand via the elbow. It is this fascinating anatomical course which may elicit problems at the medial (inside) portion of the triceps muscle, bands or swelling at the medial epicondyle (funny bone), or the ulnar wrist flexor immediately past the funny bone.

If the nerve is conceptualised as a string, then bending the elbow will stretch this string over the funny bone and reproduce symptoms. So although physiotherapy may address some of the fascial tissues adjacent to the ulnar nerve, hand physiotherapists may also splint the elbow to prevent the stretch around the funny bone.

So in regards to splinting, is keeping the elbow absolutely straight the best option?

If the space around the nerve at the funny bone is of primary concern, it is probably best to keep the elbow as straight as comfortable. MRI of the cubital tunnel shows a nice round space when the elbow is straight, which changes to an oval shape at the elbow is flexed. The oval shape is probably due to the roof of the tunnel being stretched as the elbow bends, and as it stretches it will flatten the tunnel and compress the nerve.

However, if you were to put a needle that measures pressure in the cubital tunnel whilst flexing and straightening the elbow, the pressure within the tunnel is least with the elbow at about 45 degrees away from full extension. So the recommendations to trial a towel wrapped around the elbow overnight to see if the symptoms improve may be doing the patient a disservice.

The best way to maintain a particular position of the elbow is probably with a custom made splint, limiting the elbow to 45 degrees from full extension.

And if you were to splint in this fashion, should the wrist be included? We know that extending the wrist increases the strain on the ulnar nerve; so there is a reason for including the wrist. However, we also know that as the shoulder is abducted away from the body, the strain on the ulnar nerve also increases, and it would be a brave physiotherapist to recommend keeping the arm by the side as we sleep.

All things considered, it is probably best to assess the ulnar nerve with a tensioning manoeuvre to determine the effect of the position of other joints on the symptoms.

Occasionally the wrist should be included in a straight position (never flexed). The shoulder is never included in the positioning of the arm for cubital tunnel syndrome.

So, if someone is experiencing increasing clumsiness of the hands, has tingling in the little and ring fingers, or has a particularly sore funny bone, it may be due to a cubital tunnel syndrome.

Physiotherapy intervention will typically follow thorough assessment. But if splinting is warranted, the type and position of the splint should be considered in terms of what position the elbow and/or the wrist should be, and how it fits within a treatment program.

Ray Jongs is a hand physiotherapist. He works at Royal North Shore Hospital and at BJC Health BJC Health provides a connected care multidisciplinary team philosophy to deliver positive lifestyle outcomes through a holistic approach to those with degenerative & inflammatory arthritis, tendon injury and lifestyle diseases. Our clinics are located in Parramatta, Chatswood and Brookvale. Contact us.

This blog focuses on arthritis-related diseases, healthcare in general, and our Connected Care philosophy.

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