Progressive inflammatory neuropathy

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Progressive inflammatory neuropathy
Specialty Neurology, immunology

Progressive inflammatory neuropathy is a autoimmune disease that was identified in a report, released on January 31, 2008, by the Centers for Disease Control and Prevention. [1] The first known outbreak of this neuropathy occurred in southeastern Minnesota in the United States. The disease was reported among slaughterhouse workers who appeared at various care facilities in the area reporting similar neurological symptoms. [2] [3] The disease was later identified at slaughterhouses in Indiana and Nebraska as well. [4] The condition is characterized by acute paralysis, pain, fatigue, numbness, and weakness, especially in extremities. [5] [6] It was initially believed that workers might have contracted the disease through inhaling aerosols from pig brains that were created by a machine at the slaughterhouse and that an autoimmune response to the particles might have produced their mysterious peripheral neuropathy. [1] These suspicions were confirmed in reports and investigations conducted at the Mayo Clinic in Rochester, Minnesota. [6] [7] [8] [9]

Contents

Cause

An initial comprehensive study of 24 known cases was conducted by multiple doctors from various disciplines at the Mayo Clinic. They identified the cause of this neurological disease to be long-term occupational exposure to aerosolized porcine brain and spinal tissue. [8] Investigators from the Minnesota Department of Health simultaneously determined that the air pressure jet system used to extract the brain from pig carcasses was unsafe, as it would create an airborne mist of pig organs. [1] [2] [4] The workers closest in proximity to the "head table", an area in the factory where the air system was used, were the most likely to be affected. [4] The aerosolized mist was readily absorbed into the workers' nasal mucosa. The pig proteins were then recognized by their bodies as foreign and an autoimmune response was initiated. [5] [6] [7] [8] [9] Researchers determined that the disease was due to the voltage-gated potassium channels being blocked by autoantibodies that are induced by pig brain antigen exposure, causing an intracellular build-up of potassium ions which causes inflammation and irritation, and consequently, hyper-excitability in the peripheral nervous system. It is this hyper-excitability that leads to the tingling, numbness, pain, and weakness. [9]

Researchers from the Mayo Clinic developed an animal model that involved mice receiving twice daily doses of minced pig brain tissue in saline intranasally. Biochemical testing indicated the signature autoantibodies (potassium channel antibodies, myelin basic protein antibodies and calcium channel antibodies) were present in experimental mice. [6] This animal model confirmed the hypothesized mechanism of progressive inflammatory neuropathy.

Diagnosis

Over 40 laboratory tests were initially conducted to rule out various pathogens and environmental toxins. These tests were used to try to identify potential viruses carried by humans, pigs, or both, including rotaviruses, adenoviruses, hepatitis A, and hepatitis E. Investigeatirs also tried to identify bacteria such as Salmonella and Escherichia coli, and parasites such as Giardia and Cryptosporidium that could be causing the symptoms. All of these infectious causes were ruled out. [4] [10]

Prion associated diseases such as bovine spongiform encephalopathy (BSE), chronic wasting disease (CWD), and variant Creutzfeldt–Jakob disease were also quickly ruled out as being the cause of this neuropathy. [3] [10] [1] [4]

Next two very similar autoimmune neuropathies were ruled out: Guillain–Barré syndrome is an acute autoimmune response which affects the Schwann cells in the peripheral nervous system. Guillain–Barré syndrome is usually triggered by an recent infection (or more rarely a recent vaccination) and causes weakness and tingling in the arms and legs. [2] Researchers also looked at chronic inflammatory demyelinating polyneuropathy which is characterized by progressive weakness and sensory impairment in the arms and legs. Damage occurs to the myelin sheathing in the peripheral nervous system. [3] However, as doctors at the Mayo Clinic were beginning to note, the problem they were seeing in progressive inflammatory neuropathy was occurring in the spinal nerve roots. [9]

Treatment and history

In October 2007 an astute medical interpreter noticed similar neurological symptoms being reported by Spanish-speaking patients seeking treatment from different physicians at the Austin Medical Center, in Austin, Minnesota. [11] Not only did these patients share similar neurological symptoms, they also worked at the same slaughterhouse. [4] [6] [8] [11] Dr. Daniel LaChance, a physician at both the Austin Medical Center and the Mayo Clinic in nearby Rochester, Minnesota, was notified. He launched a request to area physicians to refer other patients with similar symptoms to him. [11] The Minnesota Department of Health was notified and began an investigation into the "outbreak." [1] They identified workers from two other pork facilities in Indiana and Nebraska who also had parallel neurological complaints. Several agencies including the Occupational Safety and Health Administration and the Centers for Disease Control and Prevention were brought in to assist. Simultaneously investigations were conducted to rule out contagious disease, to locate the source or carrier, and to identify what exactly was causing these workers to develop these symptoms. [4]

Removal from exposure was the first line of treatment. Due to the progressive sensory loss and weakness, various medications were often required. These included intravenous methylprednisolone, oral prednisone, azathioprine, and/or IVIG. [7] All 24 patients improved, including 7 who received no treatment and 17 who required immunosuppressive drugs. [7] [8]

Prognosis

It is expected that there will be no new cases of progressive inflammatory neuropathy since this particular carcass processing method has been discontinued. [2] [12]

See also

Related Research Articles

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Optic neuritis describes any condition that causes inflammation of the optic nerve; it may be associated with demyelinating diseases, or infectious or inflammatory processes.

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<span class="mw-page-title-main">Somatic nervous system</span> Part of the peripheral nervous system

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<span class="mw-page-title-main">Dysautonomia</span> Any disease or malfunction of the autonomic nervous system

Dysautonomia, autonomic failure, or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic. A number of conditions can feature dysautonomia, such as Parkinson's disease, multiple system atrophy, dementia with Lewy bodies, Ehlers–Danlos syndromes, autoimmune autonomic ganglionopathy and autonomic neuropathy, HIV/AIDS, mitochondrial cytopathy, pure autonomic failure, autism, and postural orthostatic tachycardia syndrome.

<span class="mw-page-title-main">Peripheral neuropathy</span> Nervous system disease affecting nerves beyond the brain and spinal cord

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 nerves are affected. Neuropathies affecting motor, sensory, or autonomic nerves result in different symptoms. More than one type of nerve may be affected simultaneously. Peripheral neuropathy may be acute or chronic, and may be reversible or permanent.

<span class="mw-page-title-main">Demyelinating disease</span> Any neurological disease in which the myelin sheath of neurons is damaged

A demyelinating disease refers to any disease affecting the nervous system where the myelin sheath surrounding neurons is damaged. This damage disrupts the transmission of signals through the affected nerves, resulting in a decrease in their conduction ability. Consequently, this reduction in conduction can lead to deficiencies in sensation, movement, cognition, or other functions depending on the nerves affected.

<span class="mw-page-title-main">Polyneuropathy</span> Medical condition

Polyneuropathy is damage or disease affecting peripheral nerves in roughly the same areas on both sides of the body, featuring weakness, numbness, and burning pain. It usually begins in the hands and feet and may progress to the arms and legs and sometimes to other parts of the body where it may affect the autonomic nervous system. It may be acute or chronic. A number of different disorders may cause polyneuropathy, including diabetes and some types of Guillain–Barré syndrome.

Neurapraxia is a disorder of the peripheral nervous system in which there is a temporary loss of motor and sensory function due to blockage of nerve conduction, usually lasting an average of six to eight weeks before full recovery. Neurapraxia is derived from the word apraxia, meaning “loss or impairment of the ability to execute complex coordinated movements without muscular or sensory impairment”.

Astasis is a lack of motor coordination marked by an inability to stand, walk or even sit without assistance due to disruption of muscle coordination.

<span class="mw-page-title-main">Neuropathology</span> Study of disease of nervous system tissue

Neuropathology is the study of disease of nervous system tissue, usually in the form of either small surgical biopsies or whole-body autopsies. Neuropathologists usually work in a department of anatomic pathology, but work closely with the clinical disciplines of neurology, and neurosurgery, which often depend on neuropathology for a diagnosis. Neuropathology also relates to forensic pathology because brain disease or brain injury can be related to cause of death. Neuropathology should not be confused with neuropathy, which refers to disorders of the nerves themselves rather than the tissues. In neuropathology, the branches of the specializations of nervous system as well as the tissues come together into one field of study.

<span class="mw-page-title-main">Neuritis</span> Inflammation of a nerve or generally any part of the nervous system

Neuritis, from the Greek νεῦρον), is inflammation of a nerve or the general inflammation of the peripheral nervous system. Inflammation, and frequently concomitant demyelination, cause impaired transmission of neural signals and leads to aberrant nerve function. Neuritis is often conflated with neuropathy, a broad term describing any disease process which affects the peripheral nervous system. However, neuropathies may be due to either inflammatory or non-inflammatory causes, and the term encompasses any form of damage, degeneration, or dysfunction, while neuritis refers specifically to the inflammatory process.

<span class="mw-page-title-main">Chronic inflammatory demyelinating polyneuropathy</span> Medical condition

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired autoimmune disease of the peripheral nervous system characterized by progressive weakness and impaired sensory function in the legs and arms. The disorder is sometimes called chronic relapsing polyneuropathy (CRP) or chronic inflammatory demyelinating polyradiculoneuropathy. CIDP is closely related to Guillain–Barré syndrome and it is considered the chronic counterpart of that acute disease. Its symptoms are also similar to progressive inflammatory neuropathy. It is one of several types of neuropathy.

Optic neuropathy is damage to the optic nerve from any cause. The optic nerve is a bundle of millions of fibers in the retina that sends visual signals to the brain.

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<span class="mw-page-title-main">Hereditary motor and sensory neuropathy</span> Medical condition

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Peripheral mononeuropathy is a nerve related disease where a single nerve, that is used to transport messages from the brain to the peripheral body, is diseased or damaged. Peripheral neuropathy is a general term that indicates any disorder of the peripheral nervous system. The name of the disorder itself can be broken down in order to understand this better; peripheral: in regard to peripheral neuropathy, refers to outside of the brain and spinal cord; neuro: means nerve related; -pathy; means disease. Peripheral mononeuropathy is a disorder that links to Peripheral Neuropathy, as it only effects a single peripheral nerve rather than several damaged or diseased nerves throughout the body. Healthy peripheral nerves are able to “carry messages from the brain and spinal cord to muscles, organs, and other body tissues”.

References

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  10. 1 2 Centers for Disease Control and Prevention (2 May 2008). "New brain disease is blowing minds" . Retrieved 1 March 2012.
  11. 1 2 3 Gajilan, A. "Medical mystery solved in slaughterhouse" . Retrieved 19 March 2012.
  12. ↑ National Center for Zoonotic, Vector-Borne, and Enteric Diseases. "Investigation of progressive inflammatory neuropathy among swine slaughterhouse workers" . Retrieved 1 March 2012.{{cite web}}: CS1 maint: multiple names: authors list (link)
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