Diabetic amyotrophy

What is diabetic amyotrophy?

Diabetic amyotrophy is a complication of diabetes mellitus. It causes a loss of muscle bulk due to damage to the motor nerve which activates those muscles. It mainly affects the thighs, hips, buttocks and legs, causing pain and muscle wasting.

It is also called diabetic lumbosacral radiculoplexus neuropathy (DLRN) and this is becoming the more common name for this condition.

Diabetic amyotrophy symptoms

The main symptoms of diabetic amyotrophy are:

• Weakness of the lower legs, buttocks or hip.

• Muscle wasting, usually in the front of the thigh, which follows within weeks.

• Pain, often severe, usually in the front of the thigh but sometimes in the hip, buttock or back. Pain is often the first symptom that is noticed.

Other symptoms which occur in some (but not all) patients are:

• Altered sensation and tingling in the thigh, hip or buttock, which tends to be mild in comparison to the pain and weakness.

• About half of people affected lose weight.

• Constipation or diarrhoea.

• Changes in pattern of sweating.

• A reduction in blood pressure on standing.

Symptoms generally begin on one side and then spread to the other in a stepwise progression. The condition may come on quickly or more slowly and usually remains asymmetrical (ie the two sides of the body are unequally affected) throughout its course.

How long does diabetic amyotrophy last?

The condition tends to go on for several months but can last up to two years. By the end of this time there is usually complete recovery although some people are left with some minor weakness. During its course it is occasionally severe enough to necessitate wheelchair use.

Pain subsides well before the muscular strength improves. This may take months and mild- to-moderate weakness may continue indefinitely.

What causes diabetic amyotrophy?

Diabetic amyotrophy is thought to be caused by an abnormality of the immune system, which damages the tiny blood vessels which supply the nerves to the legs. This process is called microvasculitis.

Diabetic amyotrophy is more common in people with type 2 diabetes. It occurs more frequently in people who have not had diabetes for very long (the average time to develop it is 4 years after a diagnosis of diabetes) and is more common in people who have good control of their diabetes. This makes it very different from most complications of diabetes which tend to be worse if the sugar control is worse.

How common is diabetic amyotrophy?

Diabetic amyotrophy affects around 1 in 100 people with diabetes and is more common in type 2 diabetes. This is uncommon by comparison to peripheral neuropathy, which 50% of people with diabetes experience to some degree.

Diabetic amyotrophy is more common over the age of 50 (and the majority of people are over the age of 65), although younger patients can be affected. It is more common in men than women.

How is diabetic amyotrophy diagnosed?

A neurologist or diabetes specialist referral will be required for further tests.

The doctor will perform an examination, looking for muscle weakness and wasting and for changes in the leg reflexes (these usually reduce or disappear in diabetic amyotrophy).

Blood tests will often be required to look for other causes of similar conditions, such as vitamin deficiencies; diabetes control will also be reviewed. Other possible tests include:

• Lumbar puncture to look for signs of inflammation in the fluid around the spinal cord.

• Nerve conduction studies to check the workings of the nerves to the legs.

• An MRI scan of the lower back may be done to rule out compression of the nerves around the spine

How is diabetic amyotrophy treated?

Treatment mainly consists of:

• Controlling diabetes.

• Physiotherapy. (It is very important to keep muscles working as much as possible, to minimise wasting and improve the speed and degree of recovery.

• Pain relief using conventional painkillers like paracetamol or ibuprofen.

• Medication that works specifically on neuropathic pain or nerve pain, such as amitriptyline, antidepressants and antiepileptic medicines.

• Occasionally much stronger painkillers, such as opiates, might be needed.

• Steroid medications have been trialled and showed some benefit but, at the end of the trial, those who had been not prescribed steroids had recovered to the same extent as those who had. However it may be that early use of steroids might lead to some symptom relief whilst waiting for the condition to resolve itself.

• There is no evidence that other immunosuppressant medication has any benefit.

• Reassurance that this is a condition that will resolve and that the pain is not permanent.

How do I prevent diabetic amyotrophy?

Diabetic amyotrophy is not like most other complications of diabetes which can be improved by stopping smoking, maintaining a healthy weight and good diabetes control.

Diabetic amyotrophy is harder to prevent. It is best to avoid very fast reduction in blood sugars on first diagnosis of diabetes.

Good diabetes control is very important for the other complications of diabetes (which are then lifelong) but is less important for diabetic amyotrophy.

What is the outlook for patients with diabetic amyotrophy?

The outlook (prognosis) is usually good. Most patients recover completely, although there are some people who continue to have some mild symptoms.

Dr Mary Lowth is an author or the original author of this leaflet.