Acute motor axonal

neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...

(AMAN) is a variant of Guillain–Barré syndrome. It is characterized by acute

paralysis Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage. In the United States, roughly 1 in 5 ...

and loss of

reflex In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs ...

es without

sensory Sensory may refer to: Biology * Sensory ecology, how organisms obtain information about their environment * Sensory neuron, nerve cell responsible for transmitting information about external stimuli * Sensory perception, the process of acquiri ...

loss. Pathologically, there is motor axonal degeneration with antibody-mediated attacks of motor nerves and nodes of Ranvier.

Signs and symptoms

Causes

A link to ''

Campylobacter jejuni ''Campylobacter jejuni'' () is a species of pathogenic bacteria, one of the most common causes of food poisoning in Europe and in the US. The vast majority of cases occur as isolated events, not as part of recognized outbreaks. Active surveilla ...

'' was suspected when a young girl was admitted to Second Teaching Hospital. She had become ill after feeding the family chickens. She developed acute paralysis and respiratory failure. Investigators discovered that several of the chickens in the home displayed similar symptoms and ''C. jejuni'' was found in their droppings. Several of the paralysis patients were found to have antibodies to ''C. jejuni'' and anti-GD1a antibodies, suggesting a link between the pathogen and the disease. In 2015,

Zika virus ''Zika virus'' (ZIKV; pronounced or ) is a member of the virus family '' Flaviviridae''. It is spread by daytime-active '' Aedes'' mosquitoes, such as ''A. aegypti'' and ''A. albopictus''. Its name comes from the Ziika Forest of Uganda, wh ...

was linked to AMAN.

Diagnosis

The syndrome typically presents as a progressive flaccid symmetric paralysis with

areflexia Hyporeflexia is the reduction or absence of normal bodily reflexes (areflexia). It can be detected through the use of a reflex hammer and is the opposite of hyperreflexia. Hyporeflexia is generally associated with a deficit in the lower motor n ...

, often causing respiratory failure. Electromyographic studies and nerve conduction studies show normal motor conduction velocity and latency with decreased amplitude of compound muscle

action potential An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, ...

s. Pathologically, it is a noninflammatory axonopathy without demyelination. Antibodies attack the coating of the motor neurons without causing inflammation or loss of

myelin Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be l ...

. It does not affect sensory neurons, so sensation remains intact despite loss of movement.

Treatment

the majority of patients have complete symptom resolution with 5-day intravenous immunoglobulin (IV Ig) treatment. Patients with AMAN continue to see improvements in ambulation and functional ability up to four years post-diagnosis.

History

AMAN, also known as Chinese Paralytic Syndrome,Biller J. Practical Neurology, Second Edition. Lippincott Williams and Wilkins; 2002:Pg 361 was first described by a group of

Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hemisphere. It consiste ...

and

University of Pennsylvania The University of Pennsylvania (also known as Penn or UPenn) is a private research university in Philadelphia. It is the fourth-oldest institution of higher education in the United States and is ranked among the highest-regarded universit ...

neurologists in collaboration with neurologists from the Second Teaching Hospital of Hebei Medical School and Beijing Children's Hospital. In 1991, Guy Mckhann, Jack Griffin, Dave Cornblath and Tony Ho from Johns Hopkins University and Arthur Asbury from University of Pennsylvania visited China to study a mysterious

epidemic An epidemic (from Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of patients among a given population within an area in a short period of time. Epidemics of infectious d ...

of paralytic syndrome occurring in northern China. Every summer, hundreds of children from rural China developed acute paralysis and

respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise ...

. Hospitals were overwhelmed with number of cases and often ran out of

ventilators A ventilator is a piece of medical technology that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to breathe, or breathing insufficiently. Ventilato ...

and hospital beds. Examination of these children showed that many of them had acute flaccid paralysis and

but with little or no sensory loss. Electrophysiological testing of these children showed motor axonal loss with occasional conduction block with a lack of demyelinating features and normal sensory potentials. In contrast, the common form of Guillain–Barré syndrome in the West often presents with sensory loss and demyelination on electrophysiology testing and is more common in adults. Later, several autopsies confirmed the focus of the immune attack was at the motor axolemma especially around the nodes of Ranvier. These cases showed deposition of antibody and

complement A complement is something that completes something else. Complement may refer specifically to: The arts * Complement (music), an interval that, when added to another, spans an octave ** Aggregate complementation, the separation of pitch-clas ...

along the motor axolemma and associated macrophage infiltration.

References

External links

{{DEFAULTSORT:Acute Motor Axonal Neuropathy Neurological disorders Syndromes affecting the nervous system