Pathophysiology and Variant Forms
The pathophysiology of GBS is thought to be an autoimmune response against peripheral nerve components.1
The most common variant bilaterally affects motor and sensory nerves.
The key findings in GBS are profoundly-delayed conduction in nerve fibres, secondary to axonal demyelination. This occurs primarily in peripheral nerves and spinal roots, but may affect cranial nerves as well.
There is growing evidence that, at least in some cases, GBS is caused by an aberrant immune response to an infective trigger.
The subtypes of GBS3:
- Acute inflammatory demyelinating polyneuropathy (AIDP): targets myelin sheat, Schwann-cell components
- Acute motor axonal neuropathy (AMAN): targets axonal membrane
- Acute motor sensory axonal neuropathy (AMSAN)
Table 1 – Variants of GBS4
| Variant | Frequency (% of cases) | Clinical features |
| Classic sensorimotor GBS | 30-85 | Rapidly progressive symmetrical weakness and sensory signs with absent or reduced tendon reflexes, usually reaching nadir within 2 weeks |
| Pure motor | 570 | Motor weakness without sensory signs |
| Miller Fisher syndrome | 5-25 | Ophthalmoplegia, ataxia and areflexia. Incomplete forms with isolated ataxia (acute ataxic neuropathy) or ophthalmoplegia (acute ophthalmoplegia) can occur31. Overlaps with classical sensorimotor GBS in an estimated 15% of patients |
| Paraparetic | 5-10 | Paresis restricted to the legs |
| Pharyngealcervicalbrachial | <5 | Weakness of pharyngeal, cervical and brachial muscles without lower limb weakness |
| Bilateral facial palsy with paraesthesias | <5 | Bilateral facial weakness, paraesthesias and reduced reflexes |
| Bickerstaff brainstem encephalitisd | <5 | Ophthalmoplegia, ataxia, areflexia, pyramidal tract signs and impaired consciousness, often overlapping with sensorimotor GBS |
| Pure sensory | <1 | Acute or subacute sensory neuropathy without other deficits |
