Forensic Aspects - Neural Functions
A nervous system performs many high-order functions that are not easily
classified according to anatomical or chemical processes in which disorders tend to
be recognized clinically in the form of a syndrome. Five main neural
dysfunctions of complex origin and character to be discussed in this chapter
are epilepsy and seizure disorders, the phenomenon of dementia, cognitive–perceptual
deficiencies, behavioural illness, and disturbances of consciousness and coma. Five
forms of complex neurological disease pose common difficulties for the forensic
pathologist and neuropathologist because their pathology is complex or poorly
understood, and there is often a great deal of difficulty in performing
satisfactory clinical–pathological correlations using ordinary techniques.
There ere are many forms of sudden attacks that manifest themselves as
disorders of neurological function that are casually referred to as fits or
seizures. These sudden, usually transitoryattacks may have many causes that do
not immediately arise in the nervous system and may only involve it
secondarily, as in the case of Stokes-Adams attacks and various syncopal
attacks (cough syncope, micturitional syncope, etc, muscular disorders, and metabolic
diseases such as diabetes. Some apparent epileptic seizures have no electrical basis
and represent fictitious seizures or hysterical reactions. Classification of
epileptic seizures is not universally agreed upon. Without discussing the
merits of the various systems and the arguments for or against them, probably
the most universally recognized and useful is the so-called clinical and
electroencephalographic classification. According to a clinical EEG
classification, there are four basic forms of epileptic seizures:
1. Partial seizures or seizures beginning locally
2. Generalized seizures, be they bilateral or symmetrical and without
local onset
3. Unilateral or
predominantly unilateral seizures
4. Otherwise
unclassified seizures
Generalized seizures can be separated into so-called absence
attacks (petit mal seizures) or several other forms enumerated below. An
absence attacks can be simple or complex, involving not only staring but also
autonomic, motor, postural, or other functional abnormalities. Other
generalized seizures may be divided into myoclonic jerks, infantile spasms
(hypsarrhythmia), clonic seizures, tonic seizures, generalized tonic–clonic
(grandmal) seizures, or atonic–akinetic seizures. Unilateral or predominantly
unilateral seizures constitute a mixed category in which whatever the
symptomatology they show, it is primarily unilateral and not generalized. In
the case of generalized tonic–clonic convulsions (GTCs; grand mal seizure), there
may be no aura or warning of an attack. A classic GTC attack often begins with
a loud cry, loss of consciousness, and tonic contraction of muscles leading to
collapse, during which bladder and bowel control may be lost. Breathing may be
suspended and cyanosis may occur. As the seizure ends, the patient may be
drenched in sweat, be flaccid or atonic, and show Babinski signs. During the
attack, individuals are unconscious and unable to perform any meaningful or
integrated function, they are very vulnerable to accidents. They may fall and
injure themselves, drop smoking materials and ignite a fire, or injure others
by falling or violent movements. Partial or focal fits are typified by the
classic Jacksonian seizure, which usually begins with involuntary spasm of a
body part, usually an extremity (fingers, hand, toes) but it may include the
mouth. Consciousness may be preserved as long as the seizure is localized but
is usually lost during the generalized phase. Other forms of focal fits may
affect specific functional regions of the brain, such as the temporal and
limbic regions, speech centers, and visual or auditory centers. Occasionally,
verbal automatisms occur, in which nonsensical words are spoken or profanities or
abusive words or phrases are yelled. Sometimes these focal events include
spitting, involuntary urination, or defecation. Many of these types of seizure
symptoms are typical for so-called temporal lobe epilepsy or psychomotor
epilepsy. Sometimes lip movements, grimacing, or small myoclonic jerks may
accompany the fit. A greater
understanding of the organization of the cerebral cortex anatomically and
physiologically can explain many forms of seizures, especially those in which
there is structural damage or malformation of the cortex and subcortex. Recurrent
collateral fibers coming from the cortex extend into the subcortex and then arborize
upward into the cortex again to inhibit neural activity. Causes of epilepsy are
numerous and include congenital malformations, perinatal brain injury, trauma,
infection, metabolic abnormalities, vascular disease, hypoxia, electrolyte
abnormalities and dehydration (hypernatremia, hyponatremia, hypocalcemia, hypomagnesemia),
renal and hepatic failure, tumors, degenerative diseases, demyelinating diseases,
alcohol and drug toxicity and withdrawal, hyperpyrexia, and various poisons. Some
individuals experience increased seizure frequency during menstruation and in
pregnancy, where some imbalance in fluid and electrolyte metabolism may be
responsible but has not been proven. Some evidence exists that estrogen levels
may play a role in seizure thresholds, and birth control pills have been the
subject of some concern in this regard. Trauma is a common inducer of the
epileptic state, both as a primary acute event and later as a secondary chronic
event due to cortical contusion. Seizures of any clinical form, but which are
usually generalized, that occur early after trauma often connote a more serious
head injury with a much higher fatality rate than if seizures occur later. The mechanism
of seizure production is not always clear but may result from deafferentation
of cortical tissue or irritation of instability in viable cortical tissue
hemorrhage.
Epilepsy is a significant public health problem in every country of the
world, but precise and comprehensive figures on incidence are difficult to
obtain because definitions of what constitutes epilepsy vary and methods for
obtaining data are not uniform. Postmortem toxicological studies in this same
group revealed that 70 to 80% of cases had either no detectable levels of
anticonvulsants (phenobarbital or phenytoin) or subtherapeutic levels of these
agents, whereas the remainder had therapeutic levels of at least one anticonvulsant
at the time of death.
Acknowledgements:
www.politie.nl and a Chief
Inspector – Mr. Erik Akerboom ©
1. Criminal
Investigations – Crime Scene Investigation.2000
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