Where the nerve is compressed
The ulnar nerve curves around the medial epicondyle of the humerus and passes through the cubital canal, a narrow osteoligamentous tunnel behind the elbow. When you bend your arm, the canal narrows and the nerve stretches, so talking on the phone for a long time, sleeping with your arm bent, or working at a desk with your elbow supported increases the pressure inside the canal. Less commonly, the nerve is pinched lower, in Guyon’s canal at the level of the wrist: then only the hand suffers, and the sensitivity of the dorsal surface is preserved.
- The cubital canal at the elbow level is the most common area
- Guyon's canal at the wrist - less common in cyclists and after hand injuries
- Scars and bone growths after fractures
- Thickening of the ligament, cysts and ganglia near the joint
- Habitual subluxation of the nerve when bending the arm
Causes and risk factors
Most often, the cause is chronic mechanical stress: working with a constantly bent elbow, resting on the elbow on a table or on the armrest of a car, sleeping in a position with the arm pressed. A separate group consists of the consequences of injuries - a fracture of the epicondyle or dislocation of the elbow can cause neuropathy even years later. The nerve becomes more vulnerable to metabolic and systemic diseases, when its membranes tolerate pressure less well.
- Prolonged elbow flexion during sleep and at work
- Elbow support, vibrating instrument
- Fractures and dislocations in the elbow joint
- Arthrosis of the elbow and bone spurs
- Diabetes mellitus, thyroid disease
- Smoking, vitamin B12 deficiency
- Lean physique and fat loss
Symptoms and stages
It all starts with tingling and numbness in the little finger and the inner half of the ring finger, which intensifies at night and when the arm is bent. At the second stage, there is a constant disturbance of sensitivity and weakness: the fingers move in and out worse, it is difficult to hold the paper between the thumb and index finger. In advanced cases, the hand muscles lose weight, recesses appear between the fingers, and the little finger and ring finger take a semi-bent position.
- Numbness and tingling of the little finger, especially at night
- Pain along the inner surface of the elbow and forearm
- Finger clumsiness, difficulty fastening a button
- Weak grip, objects slipping out
- Weight loss of hand muscles and retraction of interdigital spaces
- Increased complaints when bending the arm for a long time
Diagnostics
The neurologist examines the arm, checks the sensitivity and strength of individual muscles, taps the nerve in the elbow area and asks to keep the arm bent to reproduce the symptoms. The key study is electroneuromyography: it shows at what level the impulse conduction is impaired and how much the muscles are damaged. An ultrasound or MRI helps to see nerve thickening, scars, cysts and bone changes, and an X-ray of the elbow helps to see the consequences of old fractures and arthrosis.
- Neurological examination with elbow flexion tests
- Electroneuromyography - confirmation of the level and extent of damage
- Ultrasound or MRI of the elbow joint
- X-ray of the elbow for past injuries
- Tests for glucose and glycated hemoglobin
- MRI of the cervical spine if there is neck pain
Treatment and prevention
In the early stages, the main treatment is not pills, but nerve unloading. A soft orthosis or bolster that keeps the elbow almost straight during sleep, avoiding leaning on the elbow, and rearranging the workplace can help. Your doctor may prescribe short-course anti-inflammatory medications, B vitamins, physical therapy, and gliding nerve exercises. If there is no improvement within 2–3 months or there is already weakness and muscle loss, surgery is discussed: freeing the nerve or moving it anteriorly from the epicondyle. All decisions are made by the doctor based on the results of the examination and electroneuromyography.
- A night brace or a homemade bolster that prevents the elbow from bending
- Refusal to rely on the elbow at the table and in the car
- Nerve gliding exercises under the supervision of a specialist
- Physiotherapy and therapeutic massage as prescribed
- Blood glucose control and smoking cessation
- Surgical decompression or nerve transposition for persistent weakness