Altered sensations in the hand may either be described as pins and needles or numbness. These sensations are caused by compression, irritation or dysfunction of the sensory nerves causing abnormality in their conduction.

These altered sensations are usually associated with other symptoms, including pain or weakness. They may develop acutely or over time, may be unilateral or bilateral i.e. involving both hands and some or all the digits may be involved.

There may be many causes for altered sensations in the hand. These vary from neurological conditions such as stroke, brain haemorrhage, multiple sclerosis, alcohol excess, vitamin B deficiency, traumatic injury to the nerves in the neck (brachial plexus) and certain drugs. 

Locally, the three most common causes are entrapment of the nerves in the neck as they emerge between the vertebrae, diabetes mellitus and carpal-tunnel syndrome.

The nerves in the neck pass through small canals or foramina and they may be compressed by the disc that is present between the vertebrae. Osteoarthritis in the neck can also produce small bony projections called osteophytes and these can also cause pressure on the cervical nerves. The patient may complain of numbness or pins and needles in the hand. There may be shooting pains down his or her arms associated with neck pain and stiffness. Weakness may also eventually develop.

The three most common causes are entrapment of the nerves in the neck as they emerge between the vertebrae, diabetes mellitus and carpal-tunnel syndrome

In carpal-tunnel syndrome, the median nerve that goes through the canal on the front of the hand does so with tendons going to the fingers. If this nerve is compressed for some reason, then the patient may develop pain in the palm occasionally radiating to the forearm. This may be associated with altered sensations in the thumb, index and middle fingers. Classically, the patient wakes up at night shaking their hand to relieve the symptoms. Carpal-tunnel syndrome is a common condition affecting one in 10 and is prevalent among females.

The diagnosis of these two conditions is essentially clinical but an MRI scan of the neck and nerve-conduction tests may help in the diagnosis. On occasion, the two conditions may be present together in a ‘double crush’ syndrome. 

While the former condition may be treated adequately by pain relief, physiotherapy, injections and, occasionally surgery, the latter condition responds very well to a release of the nerve under local anaesthetic.

Locally, diabetes is a very common endocrine problem. In addition to other complications involving the kidneys and eyes, patients may develop sensory problems. This relates to the development of a peripheral neuropathy and is more severe in patients with uncontrolled blood sugars. Nerves have small blood vessels around them which supply nutrients (vasa nervosum). These blood vessels become occluded in diabetes, resulting in lack of blood supply and hence the symptoms.

The sensory symptoms normally develop in the feet but may affect the hands and develop in a ‘glove and stocking’ distribution. The hand symptoms cause the patient to feel as if they were wearing a glove on their peripheries. 

Alistair Melvyn Pace is a consultant orthopaedic surgeon who works at St Thomas Hospital, Qormi, St James Hospital, Sliema and Da Vinci Hospital, Birkirkara.