Published on 09/04/2015 by admin
Filed under Neurology
Last modified 09/04/2015
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Peripheral neuropathies II
Clinical syndromes
Guillain–Barré syndrome (GBS) is a monophasic, predominantly motor polyradiculopathy. It develops over days to 4 weeks and can affect limbs and cranial nerves. It can vary in severity from mild weakness to complete paralysis requiring ventilatory support in 10–20% of patients. There are mild sensory symptoms and signs. At onset, reflexes may be present with significant weakness but then soon disappear. The autonomic nervous system is variably affected, producing cardiac arrhythmias and hypo- or hypertension. Recovery begins spontaneously after a few weeks.
GBS affects all ages and occurs in 2 per 100 000 per year. About 70% of patients have a history of antecedent infection: best established are Campylobacter jejuni, cytomegalovirus and Epstein–Barr virus.
Diagnosis is primarily clinical with support from neurophysiological studies and a finding of acellular CSF with raised protein. There are some patients whose neurophysiological findings indicate an axonal degeneration, the ‘acute axonal’ form of GBS, which more commonly follows Campylobacter infection.
Management consists of support and specific measures to shorten the illness. It is essential to monitor patients closely with regular measurements of vital capacity (VC) and looking for evidence of autonomic dysfunction. Patients with a VC below 1 litre require ventilation. Close attention to pressure areas, prophylaxis against venous thrombosis, and chest and limb physiotherapy are important in these vulnerable patients. Neuralgic pain can be treated with pain-modulating agents. Communication aids will be needed in paralysed patients. Helping the patient to understand their predicament and providing psychological support is important.
Two treatments have been found to shorten the course of disease. Plasma exchange and intravenous immunoglobulin will both shorten the illness to a similar degree. Both are more effective the sooner they are given (<2 weeks). They should be given to patients who cannot walk and are chair- or bed-bound.
The mortality rate is about 5%. Twenty per cent of patients have a continuing motor deficit at 1 year and 3% have a recurrence. The axonal form has a slower and less complete recovery.
The Miller Fisher variant is a rare association of areflexia, ophthalmoplegia and ataxia, and is associated with a specific antiganglioside antibody GQ1b.
There are various acquired chronic demyelinating neuropathies that have an inflammatory basis, including chronic inflammatory demyelinating neuropathy (CIDP) and multifocal motor neuropathy with conduction block. They are much less common than GBS. They may respond to immunosuppressive treatment, although the form of treatment and responsiveness vary between conditions.
Diabetes mellitus is the most common cause of neuropathies in the western world. About 15% of patients with diabetes have symptomatic neuropathies, the proportion increasing with duration of disease. Subclinical abnormalities in neurophysiological studies are almost universal after 10 years of diabetes. There are several patterns of peripheral neuropathy in diabetes.
accounts for 75% of diabetic neuropathies. It occurs more commonly in diabetics with poor glycaemic control and its frequency can be reduced (but not abolished) by tight control. This is predominantly sensory, with parallel autonomic involvement. Some patients have painful paraesthesiae; others simply have numbness. The sensory loss combined with poor circulation can lead to foot ulcers and, on occasion, neuropathic arthropathies (Charcot’s joints). Treatment is improved glycaemic control and symptomatic support.
has a whole range of synonyms, including diabetic amyotrophy or lumbosacral radiculoplexopathy. This presents with asymmetrical painful proximal weakness of the proximal muscles in the legs. It usually occurs in patients with non-insulin-dependent diabetes who have poor glycaemic control and have lost weight. Most patients improve once started on insulin with improved control.
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