What is Guillain Barre syndrome?

Guillain Barre syndrome

Guillain Barre syndrome(GBS) is a polyneuropathy which may develop over a few days or weeks after an initial infectious disease. The infection usually involves the respiratory system but it may happen after diarrheal illness and even after vaccination or surgery. It is an immunologically mediated condition.

Types of polyneuropathy:

• The most common type is acute inflammatory demyelinating polyneuropathy (AIDP) where the myelin sheath is immunologically attacked. AIDP is common in Europe and North America
• Axonal variants where the axon is affected. It may be either motor (Acute motor axonal neuropathy, AMAN) or sensorimotor (acute motor and sensory axonal neuropathy, AMSAN). These variants are more common in China and Japan.

Precipitating organisms:

• Campylobacter jejuni
• Chlamydia
• Mycoplasma pneumonia
• Hepatitis B virus
• CMV, EBV, HZV, HIV, Enterovirus

Clinical features Guillain Barre syndrome:

• History of upper respiratory tract infection or gastroenteritis (virus and bacterial)
• After 1 to 3 weeks of prior illness, weakness of the muscle starts that ascends rapidly from lower limb to upper limb and more marked in proximally than distally (ascending paralysis) 
• Distal paraesthesia and pain in limbs may occur prior to the muscle weakness
• Bulbar weakness manifested by dysphagia and nasal regurgitation
• Respiratory paralysis in about 20% of cases. In severe cases, respiratory failure can develop within a few hours.
• Loss of all reflexes
• Sensory loss; minimum or absent
• Cranial nerves may be also involved, particularly those supplying extraocular muscles, resulting in diplopia
• Sometimes, Guillain-Barre syndrome can be complicated by autonomic neuropathy manifested by accelerated HTN, tachyarrhythmia, abdominal pain and atonic bladder. 

The hallmark is an acute paralysis evolving over days or weeks with the loss of tendon reflexes. 

Investigations of GBS:

• CSF study:  The CSF protein is high (>0.55g/L)  without the presence of raised WBC (albuminocytologic dissociation). Actually, if WBC count is more than 10×10⁶  cell/L, it suggests an alternative diagnosis. 
• Frequent monitoring of respiratory function like FVC (forced vital capacity), FEV1 (forced expiratory volume in one second and PEFR (peak expiratory flow rate),  arterial blood gas analysis etc.
• Nerve conduction study: Slow conduction or conduction block
• To identify causes: Chest X-ray, stool culture or other appropriate immunological tests can be done.

The classical triad of GBS: 

• Acute asymmetrical ascending paralysis of limbs
• Areflexia and 
• Albumin-cytological dissociation

Treatment of Guillain Barre syndrome:

• The patient should be treated in ICU as artificial ventilation may be required at any time
• High dose intravenous immunoglobulin should be given to all patients. It will reduce the duration and severity if given within 14 days.
• Plasma exchange
• Physiotherapy is the main treatment option.

Prognosis of GBS:

• 80% recovery but it may take 3-6 months
• 4% of cases die
• 16% of cases will suffer from some neurological disabilities

Adverse prognostic factors of GBS:

• Old age
• Rapid deterioration to ventilation
• Evidence of axonal loss on EMG
• FVC < 1.1 L
• Arterial blood oxygen <8 kPa and carbon dioxide >6 kPa
• Coexistent lower respiratory tract infection and/or pulmonary oedema
• Accelerated HTN
• Arrhythmia
• Bulbar muscle involvement 
• Guillain Barre syndrome following Campylobacter infection (progression is very rapid and a mortality rate is as high as 5%)

Mode of death in Guillain-Barre syndrome:

• Respiratory failure due to respiratory paralysis
• Arrhythmias and hemodynamic instability due to autonomic neuropathy
• Aspiration in a patient with bulbar muscle involvement

Additional:

Miller-Fisher syndrome:

A variant of Guillain-Barre syndrome which comprises external Ophthalmoplegia, ataxia and areflexia. The presence of antibodies to the sphingomyelin component GQ1b (anti-GQ1b antibodies) is highly suggestive of this condition. 

[Source: Davidson’s 23^rd Edition: 1140, Sanjay Sharma question no: 268]