Archive | October 2016

Arthrogryptosis

imageimageArthrogryposis: nonprogressive contractures affecting one or more areas of the body prior to birth (congenitally)

A contracture is a condition in which a joint becomes permanently fixed in a bent (flexed) or straightened (extended) position, completely or partially restricting the movement of the affected joint.

When congenital contractures occur only in one body area, it is not referred to as arthrogryposis but rather an isolated congenital contracture. The most common form of an isolated congenital contracture is clubfoot.

When arthrogryposis affects two or more different areas of the body, it may be referred to as arthrogryposis multiplex congenita (AMC). The most common form of AMC is Amyoplasia. Arthrogryposis and arthrogryposis multiplex congenita are sometimes used interchangeably.

Etiology:

For many types, the cause is not fully understood. Arthrogryposis or AMC is not a specific diagnosis, but a physical finding that can be associated with numerous disorders and conditions.

It is thought to be related to decreased movement in utero, which can have multiple causes.

Neurologic and muscle problems may well be the most common causes of decreased fetal movement, but connective tissue disorders, maternal illness, and limited space are also common causes.

Some cases of AMC occur as part of rare genetic disorders that are inherited.

Some cases of AMC are related to multiple factors including genetic and environmental ones (multifactorial inheritance).

It may occur due to abnormalities or disorders associated with improper developmental of the central nervous system or the peripheral nervous system or as part of intrinsic muscle disorders.

The primary underlying mechanism that causes congenital contractures is believed to be decreased fetal movement during development. The joints begin to develop in a fetus around five or six weeks into pregnancy. Motion is essential for the proper development of fetal joints. A lack of fetal movement allows for excess connective tissue to form around the joints, which can result in the joint becoming fixed and/or limiting the movement of a joint.

Diagnosis:
made based upon identification of characteristic symptoms (e.g., multiple congenital contractures), a detailed patient history, and a thorough clinical evaluation.

Certain tests may be necessary to determine the underlying cause of AMC including nerve conduction, electromyography and muscle biopsy, which can help diagnose neuropathic or myopathic disorders.

Treatment and Management:

Standard physical therapy, which can improve joint motion and avoid muscle atrophy in the newborn period is beneficial.

Gentle joint manipulation and stretching exercises may also be beneficial.

Surgery may be necessary to achieve better positioning and increase the range of motion in certain joints, especially the ankles, knees, hips, elbows, or wrists.

Tendon transfers have been performed to improve muscle function. Tendons are the tissue by which muscle is attached to bone.

Source: https://rarediseases.org/rare-diseases/arthrogryposis-multiplex-congenita/

Herpes B virus, monkey B virus, herpesvirus B

imageimageimageMonkeys infected with B virus usually have no or only mild symptoms. In humans, however, B virus infection can result in acute ascending encephalomyelitis (inflammation of the brain and spinal cord), resulting in death or severe neurologic impairment.

Disease onset in B virus–infected humans typically occurs within 1 month of exposure, although the actual incubation period can be a little as 3 to 7 days. Symptoms associated with B virus infection include

Vesicular skin lesions (small blisters) at or near the site of exposure
Localized neurologic symptoms (pain, numbness, itching) near the wound site
Flu-like aches and pains
Fever and chills
Headaches lasting more than 24 hours
Fatigue
Muscular incoordination
Shortness of breath
Initial symptoms include fever, headache, and vesicular skin lesions at the site of exposure. Neurologic symptoms vary. Respiratory involvement and death can occur 1 day to 3 weeks after symptom onset.

Disease progression depends on the location of the exposure (usually a bite or scratch) and on the number of infectious virus particles spread during exposure. Although vesicular lesions have sometimes been observed at the exposure site, they do not always occur. The first signs of disease typically are flu-like symptoms such as fever, muscle ache, fatigue, and headache. Other symptoms that have been observed include lymphadenitis (inflamed lymph nodes), lymphangities (infection of lymph vessels), nausea and vomiting, abdominal pain, and hiccups. Once the virus spreads to the central nervous system (CNS), a variety of neurologic signs develop, including hyperesthesias (increase in sensitivity to stimuli), ataxia (lack of voluntary control of muscle movements), diplopia (double vision), agitation, and ascending flaccid paralysis (extreme weakness due to reduced muscle tone). CNS involvement is a sign of serious illness. Most patients with CNS complications will die even with antiviral therapy and supportive care, and those who survive usually suffer serious long-term neurologic problems. Respiratory failure associated with ascending paralysis is the most common cause of death.

Given the number of potential exposures for animal care workers, asymptomatic or mild human B virus infection are thought to occur, but no evidence for asymptomatic B virus infection or for latent infection has been observed in humans. Antibodies produced in response to the human herpesviruses HSV-1 and HSV-2 (present in >80% of adults) are capable of neutralizing B virus in vitro but are not protective against B virus infection. Moreover, such antibodies complicate diagnostic testing for B virus due to their high level of cross-reactivity (i.e., they increase the potential for both false-positive and false-negative results).”

source http://www.cdc.gov/herpesbvirus/signs-symptoms.html