Neurology clinic - Guillain-Barré syndrome

A 52-year-old man presented to his GP with two days of low back pain. It was described as a deep ache, with no radiation. There was no history of trauma and no disturbance of sphincter function. Neurological examination of the legs was unremarkable, with normal reflexes. The patient was reassured and provided with simple analgesia.

He returned for an emergency appointment the following day. His pain had become excruciating. He had also developed a bilateral painful tingling in the feet and calves, along with difficulty climbing stairs. There was now weakness of hip flexion bilaterally (4/5) and the knee and ankle jerks were absent. Light touch sensation was preserved.

The patient was referred as an emergency with suspected cauda equina syndrome. The accepting team confirmed the examination findings, demonstrated normal anal tone and saddle sensation, and arranged an urgent MRI of the lumbar spine. Vital signs, temperature and admission bloods were normal, except for modest hyponatraemia.

During monitoring on the admission unit, episodes of self-resolving bradycardia and hypotension were observed. Over the next few hours the patient reported a feeling of heaviness in his arm. The MRI proved normal, and a neurological opinion was sought. The neurology registrar obtained a history of a coryzal illness two weeks previously, and noted progressive, largely proximal and symmetrical weakness of the legs and arms, with bilateral, mild lower motor neuron facial palsy and global areflexia.

A diagnosis of Guillain-Barré syndrome (GBS) was made. Pregabalin was introduced for neuropathic pain, and regular monitoring of vital capacity and neurological function recommended. A lumbar puncture was performed, which demonstrated no abnormalities. Nerve conduction studies were arranged.

The day after admission, the patient was unable to walk, weakness now affecting distal as well as proximal muscles. A decision was made to commence intravenous immunoglobulin. Vital capacity fell through the day, and the patient was transferred to intensive care before being intubated and ventilated. Ventilatory support was weaned after three weeks, and the patient returned to the ward one week later. With time and regular physiotherapy his strength slowly improved. By 12 weeks he was able to stand. Three weeks later he could walk short distances with support, and at six months was able to walk unsupported. On examination a year after admission, there was mild weakness of ankle dorsiflexion only, but the patient was still significantly limited by fatigue.

The problem

GBS is an acute, inflammatory polyradiculoneuropathy with an annual incidence of 1-2/100,000 per year. The syndrome is more common in men and with advancing age.¹ In about 65% of cases patients report an antecedent infection (usually respiratory or gastrointestinal) one to four weeks before the onset of neurological symptoms. Often the exact organism is not identified – if it is, Campylobacter jejuni is the most likely culprit.² There is likely to be a small risk associated with influenza immunisation, but this is probably outweighed by the risk associated with influenza itself.³ The pathophysiological mechanism is felt to be transient autoimmunity triggered by infection. In some cases, antibodies that cross-react with both the infecting organism and human peripheral nerve can be detected.⁴

Features

Diagnostic criteria stress that progressive weakness of all limbs and areflexia are required, although these features may be absent in GBS variants or atypical cases. Progression over days to four weeks, relative symmetry and autonomic dysfunction are also typical features.⁵ Pain is frequently present, and can precede weakness in over a third of patients, when it is usually localised in the lower back, neck or intrascapular region.⁶

That weakness ‘ascends’ in GBS is well known, but as the pathology is most often demyelinating and involves spinal roots, proximal weakness is common. As such, the weakness usually ascends from the legs to the arms, then cranial nerves and respiratory muscles – and not necessarily from distal to proximal muscles in a limb.

Diagnosis

The diagnosis of GBS is largely clinical, based on the presence of the above features, and supported by CSF analysis (raised protein) and nerve conduction studies performed in the hospital setting. However, both of these can be normal, especially early in the disease. A cellular CSF is a strong pointer to an alternative diagnosis.

In practice, the most common differential is compressive or inflammatory spinal cord disease – suggested clinically by a sharp sensory level, early urinary retention or the later development of upper motor neurone signs. Occasionally, GBS can be mimicked by other processes, such as an acute toxic or nutritional neuropathy, infection (Lyme), HIV seroconversion, or progressive lymphomatous infiltration of the nerve roots.

Management

The important early management is supportive – close monitoring of vital capacity, early transfer to intensive care if required, thromboprophylaxis to prevent pulmonary embolism and nursing care to prevent pressure sores requiring admission.

A five-day course of intravenous immunoglobulin reduces disability at four weeks and the time taken to recover independent walking. Despite treatment and respiratory support the mortality rate is 5%.⁷ High intensity rehabilitation during the recovery phase further improves functional outcome⁸, but significant proportions of patients do not recover completely, and many suffer persistent fatigue or cannot return to their previous occupation.⁹ About 5% have more than one episode.¹⁰

Dr Simon Rinaldi is a clinical lecturer in neurology at the University of Oxford.

References