Encephalopathy
<neurology, pathology> Any degenerative disease of the brain.
Origin: Gr. Pathos = disease
(18 Nov 1997)
Encephalopathy is a term for any diffuse disease of
the brain that alters brain function or structure. Encephalopathy may be caused by
infectious agent (bacteria, virus, or prion), metabolic or mitochondrial dysfunction,
brain tumor or increased pressure in the skull, prolonged exposure to toxic elements
(including solvents, drugs, radiation, paints, industrial chemicals, and certain metals),
chronic progressive trauma, poor nutrition, or lack of oxygen or blood flow to the brain.
The hallmark of encephalopathy is an altered mental state. Depending on the type and
severity of encephalopathy, common neurological symptoms are progressive loss of memory
and cognitive ability, subtle personality changes, inability to concentrate, lethargy, and
progressive loss of consciousness. Other neurological symptoms may include myoclonus
(involuntary twitching of a muscle or group of muscles), nystagmus (rapid, involuntary eye
movement), tremor, muscle atrophy and weakness, dementia, seizures, and loss of ability to
swallow or speak. Blood tests, spinal fluid examination, imaging studies,
electroencephalograms, and similar diagnostic studies may be used to differentiate the
various causes of encephalopathy.
-National Institute of Neurological Disorders and
Stroke http://www.ninds.nih.gov/disorders/encephalopathy/encephalopathy.htm
- Comment in:
Acute encephalopathy followed by permanent brain injury or death
associated with further attenuated measles vaccines: a review of claims submitted to the
National Vaccine Injury Compensation Program.
Weibel
RE, Caserta
V, Benor
DE, Evans
G.
Division of Vaccine Injury Compensation, National Vaccine Injury Compensation Program,
Health Resources and Services Administration, Public Health Service, Rockville, Maryland
20857, USA.
OBJECTIVE: To determine if there is evidence for a causal relationship between acute
encephalopathy followed by permanent brain injury or death associated with the
administration of further attenuated measles vaccines (Attenuvax or Lirugen, Hoechst
Marion Roussel, Kansas City, MO), mumps vaccine (Mumpsvax, Merck and Co, Inc, West Point,
PA), or rubella vaccines (Meruvax or Meruvax II, Merck and Co, Inc, West Point, PA),
combined measles and rubella vaccine (M-R-Vax or M-R-Vax II, Merck and Co, Inc, West
Point, PA), or combined measles, mumps, and rubella vaccine (M-M-R or M-M-R II, Merck and
Co, Inc, West Point, PA), the lead author reviewed claims submitted to the National
Vaccine Injury Compensation Program. METHODS: The medical records of children who met the
inclusion criteria of receiving the first dose of these vaccines between 1970 and 1993 and
who developed such an encephalopathy with no determined cause within 15 days were
identified and analyzed. RESULTS: A total of 48
children, ages 10 to 49 months, met the inclusion criteria after receiving measles
vaccine, alone or in combination. Eight children died, and the remainder had mental
regression and retardation, chronic seizures, motor and sensory deficits, and
movement disorders. The onset of neurologic signs or symptoms occurred with a
nonrandom, statistically significant distribution of cases on days 8 and 9.
No cases were identified after the administration of monovalent mumps or rubella vaccine.
CONCLUSIONS: This clustering suggests that a causal relationship between measles vaccine
and encephalopathy may exist as a rare complication of measles immunization.
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