GBS includes postinfectious polyneuritis, acute inflammatory demyelinating polyradiculoneuropathy, infective polyneuritis and infectious polyradiculitis.
Definition
The term is applied to a nonspecific viral infection/ inflammatory disorder of peripheral nerves and nerve roots characterized by symmetrical muscle weakness, sluggish or absent tendon reflexes, paresthesia or other sensory disturbances and autonomic dysfunction. Maximum cases are seen in the age group of 5–12 years.
Etiopathogenesis
The condition has a definite relationship to diseases such as measles, chickenpox and rubella. Infectious mononucleosis (glandular fever), mumps, influenza and coxsackie or enteric cytopathic human orphan (ECHO) has also been incriminated. What is important is that the polyneuritis usually starts after a substantial interval of about 10 days following the viral infection. Hence, the term postinfectious appears to be most appropriate.
The mechanism of causation is not too clear. It appears that breakdown of the nerve myelin occurs as an autoimmune process following the migration of the peripheral lymphocytes that have been sensitized to a protein component of the myelin. As a result, the myelin undergoes destruction.
Clinical Features
- The earliest manifestation is a muscle pain followed by weakness in the proximal as well as distal group of muscles.
- Characteristically, muscle involvement is symmetrical in distribution and not in extent (Fig. 30.8).
- Muscle involvement first begins in the lower limbs and then spreads to the trunk, upper limbs and face.
- Muscle tone is reduced, so are the tendon reflexes. Plantars are usually down going.
- Involvement of the intercostal muscles may lead to respiratory difficulty.
- Hypertension or urinary retention may result from involvement of the autonomic system.
- There may be sensory symptoms, e.g. paresthesias.
- Involvement of cranial nerves VIII, IX, X and XI may occur. The most frequently involved one is, however, facial nerve.
- Infrequently, the disorder may present as ataxia.
- GBS with involvement of cranial nerves and cerebellar signs is termed Miller-Fisher variant.
Diagnosis
The CSF usually shows a characteristic cytoalbuminous dissociation toward the second week of illness. Often the protein may be as high as 400–500 mg%, though the cell count remains normal or only slightly raised.
Fig. 30.8: Guillain-Barré syndrome. The child started with flaccid paralysis of the lower limbs with some sensory loss. Paralysis ascended to involve respiratory muscles causing increasing respiratory distress warranting the use of a ventilator.
The so-called cytoalbuminous dissociation (also called albuminocytologic dissociation) in a child with acute or subacute polyneuropathy is considered pathognomonic (diagnostic) of GBS.
- Motor nerve conduction velocities and sensory conduction time are slow.
- Electromyography reveals acute denervation of muscle.
- Muscle and nerve biopsies, though not needed for diagnosis, show denervation atrophy and demyelination and degeneration and inflammation, respectively.
Differential Diagnosis
Differential diagnosis is from:
- Acute flaccid paralysis, i.e. poliomyelitis, traumatic myelitis and transverse myelitis
- Polyneuritis following diphtheria, enteric fever, botulism, tick-bite paralysis
- Other illnesses such as polymyositis and cerebellar ataxia.
Treatment
Supportive treatment is more or less on the same lines as in poliomyelitis.
- Plasma exchange (plasmapheresis) or high-dose intravenous (IV) gamma globulins (IVIG), l g/kg/day for 2 days or 400 mg/kg/day for 5 days, is the treatment of choice at present. This treatment helps by removing the circulating immune complexes.
- Severe illness with respiratory paralysis/failure requires management with assisted ventilation. Prevention of decubitus ulcers in case of flaccid tetraplegia and prevention/treatment of secondary bacterial infections are vital.
- Chronic relapsing GBS needs repeated plasma exchange. Steroids, especially high-dose pulsed methylprednisolone by IV route, may be used as less effective alternative modality
Steroids, including high-dose pulsed methylpredniso- lone by IV route, though used in the past, are no longer recommended.
Prognosis
Most cases (60–70%) usually show complete recovery within a few weeks to months. At times, it may take as much as 2 years. Mortality (around 5%) is usually secondary to respiratory complications. Many subjects with chronic relapsing GBS end up with considerable residual disability in the form of foot drop, pes cavus, postural tremors and weakness of limbs and trunk.
