Acute motor axonal

neuropathy Peripheral neuropathy, often shortened to neuropathy, refers to damage or disease affecting the nerves. Damage to nerves may impair sensation, movement, gland function, and/or organ function depending on which nerve fibers are affected. Neuropa ...

(AMAN) is a variant of

Guillain–Barré syndrome Guillain–Barré syndrome (GBS) is a rapid-onset Paralysis, muscle weakness caused by the immune system damaging the peripheral nervous system. Typically, both sides of the body are involved, and the initial symptoms are changes in sensation ...

. It is characterized by acute

paralysis Paralysis (: paralyses; also known as plegia) is a loss of Motor skill, motor function in one or more Skeletal muscle, muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory d ...

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

nodes of Ranvier Nodes of Ranvier ( ), also known as myelin-sheath gaps, occur along a myelinated axon where the axolemma is exposed to the extracellular space. Nodes of Ranvier are uninsulated axonal domains that are high in sodium and potassium ion channels ...

Signs and symptoms

Causes

A link to ''

Campylobacter jejuni ''Campylobacter jejuni'' is a species of pathogenic bacteria that is commonly associated with poultry, and is also often found in animal feces. This species of microbe is one of the most common causes of food poisoning in Europe and in the US, w ...

'' 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, where ...

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. 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 neurons (at t ...

, often causing respiratory failure. Electromyographic studies and

nerve conduction studies A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called ...

show normal motor conduction velocity and latency with decreased amplitude of compound muscle

action potential An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific Cell (biology), cell rapidly ri ...

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 Sheath ( ) is a lipid-rich material that in most vertebrates surrounds the axons of neurons to insulate them and increase the rate at which electrical impulses (called action potentials) pass along the axon. The myelinated axon can be lik ...

. 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. "Physiotherapy assessment and treatment can help prevent the decline of functional status and maintain functional independence, muscle strength, posture, balance, and cardio-respiratory fitness."

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 The Johns Hopkins University (often abbreviated as Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland, United States. Founded in 1876 based on the European research institution model, J ...

and

University of Pennsylvania The University of Pennsylvania (Penn or UPenn) is a Private university, private Ivy League research university in Philadelphia, Pennsylvania, United States. One of nine colonial colleges, it was chartered in 1755 through the efforts of f ...

neurologists Neurology (from , "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the nervous system, which comprises the brain, the s ...

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 hosts in a given population within a short period of time. For example, in meningococcal infection ...

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 r ...

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

ventilators A ventilator is a type of breathing apparatus, a class 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 breathi ...

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

flaccid paralysis Flaccid paralysis is a neurological condition characterized by weakness or paralysis and reduced muscle tone without other obvious cause (e.g., trauma). This abnormal condition may be caused by disease or by trauma affecting the nerves associ ...

and

but with little or no sensory loss.

Electrophysiological Electrophysiology (from ee the Electron#Etymology, etymology of "electron" ; and ) is the branch of physiology that studies the electrical properties of biological cell (biology), cells and tissues. It involves measurements of voltage change ...

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 An autopsy (also referred to as post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death; ...

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 Complement may refer to: The arts * Complement (music), an interval that, when added to another, spans an octave ** Aggregate complementation, the separation of pitch-class collections into complementary sets * Complementary color, in the visu ...

along the motor axolemma and associated

macrophage Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...

infiltration.

References

External links

* Acute Motor Axonal Neuropathy (AMAN), a Variant of Guillain-Barre Syndrome: A Case Study {{DEFAULTSORT:Acute Motor Axonal Neuropathy Peripheral nervous system disorders Syndromes affecting the nervous system