Case study: Strange pain and tingling in lower legs

Four criteria permit the diagnosis of restless leg syndrome, writes Dr Julian Spinks

Margaret had first noticed strange sensations in her legs at night when she was in her early twenties, but these did not happen very often and were not bad enough for her to see a doctor.

Over the next 20 years, the episodes became more frequent and the symptoms more severe. By the time she was 45 she was waking several times a week and it was leaving her exhausted. As a result, she decided to mention it to her GP when she next saw him.

Margaret told her GP she was ‘worn out’ because she couldn’t sleep. He asked a few questions and decided it was simple insomnia and advised her about sleep hygiene.

At the next consultation, Margaret mentioned the strange sensations she experienced at night, which she said were a mixture of a pain and a tickle. They only disappeared if she moved her legs. The GP felt this was cramp and prescribed quinine.

Over the years, Margaret returned and received several diagnoses including anxiety and sciatica.

Finally, she was given temazepam and amitriptyline. These helped her sleep a little but, if anything, made the leg sensations worse.

Throughout this time, Margaret’s actual problem was restless legs syndrome (RLS).

Most of the treatments would have made no difference, and some may have worsened the symptoms.

There are four essential criteria that must be met to diagnose RLS (see box). Additional features that support the diagnosis are family history — in around 40 per cent of cases, periodic limb movements in sleep — clonic-type movements in the legs which may be noticed by the patient’s spouse; a progressive clinical course and responsiveness to dopaminergic therapy.

Unclear presentation

RLS often does not present with a clear-cut picture. The commonest presentation is with sleep disturbance which can be mistaken for insomnia or depression.

In addition, the sensations are varied and difficult to describe. Descriptions include aching, burning, itching, pulling and also phrases like ‘fizzy blood’, ‘crazy leg’ and ‘Elvis legs’. These descriptions can send the clinician in the wrong direction.

Most RLS is primary, but it can occur secondary to other conditions, most commonly iron deficiency (up to a quarter of older RLS patients), pregnancy, and end-stage renal disease (ESRD), especially in dialysis patients and those with vitamin B12/folate deficiency.

RLS is associated with chronic diseases including diabetes, rheumatoid arthritis, Parkinson’s disease and peripheral neuropathy.

RLS has no clinical signs but a neurological examination should be carried out to exclude neuropathy and other neurological conditions. Peripheral pulses should also be examined for vascular disease.

Blood tests such as FBC, iron studies, particularly ferritin, U&Es/creatinine, vitamin B12/ folate, blood glucose and thyroid function tests, should be organised to detect secondary causes. In some cases, sleep studies can help map sleep patterns.

Treatment consists of removal of secondary causes and precipitating factors, modification of lifestyle factors as well as drug therapies.

Secondary causes such as ESRD should be treated. If iron deficiency is present, iron supplementation should be given, aimed at raising the ferritin above 45ng/l.

Some drugs such as antidepressants (including amitriptyline), calcium blocker drugs  and anti-emetics can worsen RLS.

Lifestyle modification

In milder cases of primary RLS, modification of lifestyle factors can be the only treatment. It includes advice about sleep hygiene, avoidance of caffeine and alcohol in the evening and the use of techniques such as massaging the affected limbs, stretching, walking, hot/cold baths and relaxation techniques.

RLS appears to be linked to post-synaptic dopaminergic dysfunction, so treatment is aimed at correcting this.

The first-line drug therapy for RLS is a non-ergot dopamine agonists. Two drugs in this class — pramipexole and ropinirole — are the only licensed treatments for RLS in the UK.

In clinical trials these have a good success rate. The doses are lower than those used for Parkinson’s disease and the treatment may be titrated upwards until relief is achieved.

Nausea and daytime sleepiness are possible side-effects about which the patient should be counselled.

Levodopa has also been used successfully off-licence but over 80 per cent of patients develop augmentation — the spread of the condition to the upper limbs or rebound — the reappearance of symptoms in the morning. In resistant cases, other off-licence drugs include gabapentin, opiates,and hypnotics for severe insomnia.

These are better reserved for use under specialist supervision. There are no safety data for RLS treatments in pregnancy. In cases of diagnostic uncertainty or treatment failure, referral to a neurologist should be considered or sleep specialist with an interest in RLS.

Margaret moved to another town. Her new GP suspected RLS and the amitriptyline was stopped. She was given pramipexole 0.125mg rising to 0.250mg. On the larger dose her symptoms disappeared.


Dr Spinks is a GP with an interest in movement disorders in Strood, Kent

Criteria for the diagnosis of RLS

A need to move the legs, usually accompanied or caused by uncomfortable, unpleasant sensations in the legs.

The need to move and sensations are exclusively present, or worsen, during periods of rest/inactivity.

The need to move or sensations are relieved by movement such as walking or stretching for as long as the activity continues.

The need to move and sensations are generally worse or exclusively occur in the evening and night.

Lessons learnt from this case

RLS frequently presents with sleep disturbance.

The sensations in the legs are varied and many patients have difficulty describing them.

Diagnosis is based on a history of four essential criteria.

In around 25 per cent of patients there may be iron deficiency.

Other common secondary causes are renal disease and pregnancy.

Treatment includes treatment of secondary causes and advice about lifestyle and sleep hygiene.

If drug therapy is required, dopamine agonists are the first-line treatments. Pramipexole and ropinirole are currently licensed for this indication.

References

Montplaisir J, Nicholas A, Denesle R, Gomez-Mancilla B. Restless legs syndrome improved by pramipexole: a double-blind randomised trial. Neurology 1999; 52: 938–43.

Trenkwalder C, Garcia-Borreguero D, Montagna P, Lainey E, de Weerd A W, Tidswell P, et al. Ropinirole in the treatment of restless legs syndrome: results from the TREAT RLS 1 study, a 12 week, randomised, placebo-controlled study in 10 European countries. J Neurol Neurosurg Psychiatry 2004; 75: 92–7.

Walters A S. Toward a better definition of the restless legs syndrome. Mov Dis 1995; 10: 634–42.

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