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Editor,—Chinese motor paralysis, or acute motor axonal neuropathy, is a recently recognised acute inflammatory neuropathy that differs from classic Guillain–Barré syndrome in clinical, neurophysiological, and pathological features.1Cases have been reported from China, Japan, India, and South America,1-3 but not previously in northern Europe.
A 14 year old boy presented with a five day history of poor grip and falling from his bicycle, followed by progressive symmetrical mainly proximal weakness affecting both upper and lower limbs equally, without an ascending picture. He had been constipated for two days and had developed hoarseness and a weak cough. There was no other relevant history. Examination showed mild weakness of jaw opening and facial musculature; complete inability to flex his neck against gravity (MRC 2) with normal neck extension (MRC 5), and predominantly proximal weakness (MRC 3) with less severe distal weakness (MRC 4). Distal tendon jerks were absent, but proximal jerks could be elicited. His peak flow rate was 30% of predicted.
He received intravenous immunoglobulin (IVIG) 0.4 g/kg daily for five days. On day 2 he required intubation and artificial ventilation. By day 3 he developed bilateral ptosis, swallowing difficulties requiring tube feeding, and upgoing plantar responses. Constipation persisted until day 4 when an enema was given. Despite the severe axial and proximal weakness, distal power was less affected to the extent that he was still able to write clumsily. By day 5 he began to improve; he was extubated on day 14, walked with support on day 19, and walked alone on day 37. However, only by 22 months was power completely normal. He also developed a unilateral neuropathic tremor.
Investigations showed an initial lymphopenia, normal cerebrospinal fluid at 48 hours with a protein of 0.4 g/l, a rise in serum creatine kinase to seven times the upper limit of normal by day 3, which fell to normal by day 8, and normal serum IgM anti-GM1 and IgM anti-Mag titres. Campylobacter jejuni (untypeable) was isolated from rectal swabs. Muscle biopsy on day 4 showed some central nuclei and two small angulated fibres only. Neurophysiological investigations at seven and 15 days after onset showed pronounced reduction of the amplitudes of the compound muscle action potentials, but normal distal latencies, motor nerve conduction velocities, and sensory nerve conduction studies.
This is the first report of Chinese motor paralysis acquired in northern Europe. Our patient resembled previous reports from Asia in that he had severe involvement of facial, bulbar, and neck flexor muscles, rapidly progressive weakness, respiratory failure needing ventilatory support within 48 hours of admission, and a rapid early recovery, together with electrophysiological findings suggestive of a motor axonal neuronopathy and campylobacter infection.4 He differed in that the weakness was mainly proximal with relatively good power distally, and in the absence of an ascending picture. Pathological studies revealed complement deposition and myelin vesiculation followed by macrophage invasion at the nodes, and later prominent Wallerian-like degeneration of myelinated motor fibres in the ventral roots and nerves, with only minimal inflammation or demyelination and relative sparing of dorsal roots even in advanced cases.5 In China annual epidemics occur associated with campylobacter infection. Apart from supportive therapy, treatment is not well defined.
Acute demyelinating neuropathy, acute sensory and motor axonal neuropathy, Miller−Fisher syndrome, and now acute motor axonal neuronopathy are currently recognised subtypes of Guillain–Barré syndrome.1 6 7 Why acute motor axonal neuronopathy differs so much from the combined form, which has a slower and poorer recovery, is uncertain. Our patient’s course suggests two mechanisms can be involved, one with relatively rapid recovery and the other with a more typically axonal course.
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