Morpho-functional peculiarities of neural system

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Transcript Morpho-functional peculiarities of neural system

peculiarities of
nervous system
Department of pediatrics
The nervous system consist of
the brain,
 the spinal cord,
 the peripheral nervous system,
 the autonomic nervous system
 sense organs (sight, heating, olfactory,
taste, skin sensitivity).
The main nervous system’s functions are:
-psychological (intelligence) activity;
-locomotion activity (function);
-neural regulation of vegetation functions.
- the nervous system realizes coordination of
psychological and metabolic processes in
different tissues, organs and systems and
realizes connection between the organism
and environment.
The Brain During Development
The nervous system develops from embryonic tissue called the
ectoderm. The first sign of the nervous system developing is the
neural plate that can be seen at about the 16th day of development.
Over the next few days, a "trench" is formed in the neural plate - this
creates a neural groove. By the 21st day of development, a neural
tube is formed when the edges of the neural groove meet. The
rostral (front) part of the neural tubes goes on to develop into the
brain and the rest of the neural tube develops into the spinal cord.
Neural crest cells become the peripheral nervous system.
The nervous system is originated
Forepart of medullar
tube growths and
gives the origin of
brain bubbles during
5-6 weeks of
intrauterine period.
The nervous system is originated
Five parts of brain – 2
hemispheria, connected
by telencephalon,
myencephalon, are
formed from back part of
madullar tube.
The Brain During Development
Almost all the convolutions and fissures (gyre and sulcus) the brain
is to possess in later life are present at birth, but they are extremely
underdeveloped. The layers of the cerebral cortex are already
almost completely formed at term, but differentiation of all the nerve
cells occurs predominantly in the postnatal period. At the same time
the spinal cord, the optic thalamus, and the corpus striatum are of a
more mature structure. The cerebellum is elongated and its sulci are
weakly pronounced.
It is only towards the end of the first year of life that
macroscopic structure of baby’s brain approaches that of an adult.
Differentiation of the brain matter (nerve tissue, ganglionic cells and
nerve fibers) is slower.
Development of the spinal cord
Critical period
The most intensive fission of neural cells
occurs between 6 and 18 weeks of
intrauterine period. We call this period “the
critical period” of CNS development due to
possibility of the influence of various
teratogenic factors to fetus nervous
system, formation the defects of
development of the nervous system is
Development of the brain
Since the cortical layers of the brain of the newborn infant are little
differentiated the formation of the cortical centers is also immature.
An intensive development of the cerebral cortex takes place during
the first three month after delivery.
A most characteristic point is the absence of dendrites
(arboraceous branches) in the nerve cells (neurons).
Principal differentiation of the nerve cells is completed by the age of
3 years, although the final termination of the process occurs only at
8 years.
The conduction routes (with the exception of the pyramidal
pathways) are sufficiently developed at birth; the pyramidal routes
myelinize by the time the baby is 5 or 6 month old.
According the existing date the first neuron pathways to become
myelinized in the cerebral hemispheres are the efferent routes, while
pyramidal myelinization (the efferent pathway) occurs later.
A significant aspect of brain development is the continued growth of
myelin sheaths around the axons of the cerebral cortex. Myelin is a
fatty substance which is deposited around many (though not all)
axons as an insulating sheath. Its presence allows conduction of
nerve impulses to occur from ten to one hundred times as rapidly as
would occur along a non-myelinated axon. Since this obviously
increases the efficiency of the axon system (just as increased
computing speed enhances the efficiency of a computer), the
development of axonal sheaths are taken as a measure of
increasing maturity of the neural system involved.
Myelin sheath development, or myelinization as it is called, has a
rather well recognized time table in the cerebral hemispheres. Fibers
serving the primary sensory (touch, vision, audition etc.) and motor
areas are myelinated shortly after birth while those which are
involved with more complex associative and cognitive functions
myelinate later.
It is generally believed that fiber systems of the prefrontal lobes
(executive functions, intentions, future planning, etc.) are among the
latest to myelinate, a process that may go on into young adulthood.
The spinal cord
is almost prepared to function at birth. Its weight at that time is 2 to
6g and subsequent gains are less intensive than those of the brain.
The growth of the spinal cord runs parallel to the development of
motor function – its initial weight triples by the age of 5 years;
however, in distinction from brain the structure of the spinal cord
approaches adult structure already in the second year of life. The
only subsequent increase is in number of motor cells in the ventral
(anterior) horns. By puberty the spinal cord increases four to fivefold.
The intracranial nerves myelinize by the three month after birth, the
peripheral nerves by three years, but growth of the myelin sheath
and even of the axis cylinder continues.
The autonomic nerves system functions from the moment of birth.
So, the morphological features most characteristic of the nervous
system in early childhood are immaturity of cerebral cortex, meager
differentiation of the nerve cells, and insufficient myelinization of the
nerve fibers.
Clinical summary
The great excitability and tendency to
affective states characteristic of very
young children are due to prevalent
development of the subcortical centers
and the decrease of inhibitory activity of
the cortex at this age.
Development of the sense organs
Hearing – the receptive abilities of the auditory
analyzers, develops in the child from the time he is two
weeks old.
Vision – as a reflex to object is defined from the third
month of life; transient strabismus and absence of
coordinated movement of the eyeballs are physiological
phenomena in the newborn.
The olfactory sense (smell) develops gradually in the
form of reflex to odors after the age of six months, but
the perception of taste appears much earlier.
Clinical correlates
Most defects of the spinal cord result from
abnormal closure of the neural folds in the
3rd and 4th weeks of development.
 The resulting abnormalities are known as
neural tube defects (NTDs), which also
involve the meninges, vertebrae, muscles,
and skin.
Spina bifida
refers to a splitting of the vertebral arches and may or
may not involve underlying neural tissue.
The incidence for severe neural tube defects is
approximately 1 in 1000 but varies in different
refers to a defect in the vertebral arches that is covered
by skin and usually does not involve underlying neural
tissue. It occurs in the lumbosacral region (L4—S1) and
is usually marked by a patch of hair overlying the
affected region. The defect is due to a lack of fusion of
the vertebral arches and is present in about 10% of
otherwise — normal people.
Spina bifida cystica
can be diagnosed prenatally (!)
 by ultrasound investigation
 and by determination of α—fetoprotein
(AFP) levels in maternal serum and
amniotic fluid. The vertebra can be
visualized by 12 weeks of gestation, and
defects in closure of the vertebral arches
can be detected.
Clinical methods of examination of Central
Nervous System
include interrogation,
examination of muscular strength,
examination of physiological and pathological reflexes,
diagnostic of pathological symptoms and syndromes,
examination of child’s mental development, behavior
The interrogation
includes information about complaints,
 history of the disease,
 anamnesis of vitae according the schema
of the case history.
The history is the most important component of the evaluation
of the child with neurology problem. It should carefully document in
chronological order the onset of symptoms. A comprehensive review
of systems also is essential.
It is important to start with concise description of the chief complaint
within its developmental context. A comprehensive understanding of
developmental milestones is essential in order to ascertain the
relative importance of the parents` observations.
Following the chief complaint and history of present illness, a review
of pregnancy, labor, and delivery is indicated, particularly if a
congenital disorder is suspected. Maternal exposure of infections,
drugs, cigarettes and alcohol during the pregnancy is important
associated with the congenital myophathies and other
neuromuscular disorders.
The history of birth weight, length and head circumference are
particularly important.
Apgar scores, need for ventilator assistance, and history of feeding
difficulties should be noted.
The most important component of the neurology history is the child`s
developmental assessment. An abnormality in development from
birth suggests an intrauterine or perinatal cause. A slowing of the
rate of acquisition of skills later in infancy or childhood suggests an
acquired abnormality of the nervous system. A loss of skills over
time strongly suggests an underlying degenerative disease of the
central nervous system.
The family history is extremely helpful in the neurology evaluation of
the child. The history should document the presence of neurologic
disease, including epilepsy, migraine, strokes and heredofamilial
disorders. It also should be determined whether the parents are
includes details of
 head shape, size,
 posture,
 locomotion activity,
 child behavior,
 muscle bulk,
 pathological symptoms.
Observation of the child
behavior and play provides useful information
must be modified for infants and children of
various ages. The examination should be
conducted in a setting that is nonthreatening and
enjoyable for the child. The more it seems like a
game the greater will be the degree of
Evaluation of the motor function, gait, and
coordination should precede the more
threatening head and cranial nerve examination.
Paraclinical methods of
Include central spinal fluid CSF examination,
skull roentgenography,
Computer tomography,
cerebral angiography,
cranial ultrasound,
“Light- brain” – is a sing of meningitis
Focus of necrosis of brain
Focus of ischemia of brain
Ultrasound investigation –
intracranial left-side hemorrhage
Computer tomography - intracranial hemorrhage
Differential diagnosis of syndrome of
meningism, purulent and serous meningitis
Parameters of
cerebrospinal fluid
The normal
Pressure (mmH2O)
Frequency of drops
from the needle(per
Cytosis**(10 9/L)-all
kinds of cells
Lymphocytes (%)
Neutrophiles (%)
Protein (g/L)
Reaction of pandy***
Condition after
lumbar puncture
Head ache,
vomiting when a
quantity is
The diagnosis
Syndrome of
Milky, greenish
0,002 – 0,008
Frequency lesser
then normal*
improvement for
a short period of
Significant relief
often becomes
the turning point
of the disease
Significant relief
often becomes
the turning point
of the disease
The main clinical symptoms of
nervous system diseases
are headache, dizzines, disorder of motor
function (apraxia, ataxia, hyperkinesiscramp, tremor, changes of muscular
tonus, gait, paralysis, disorders of
consciousness, speech, reflexes activity,
sleep, cranial nerves, sensitivity and
Syndrome of movement and reflex
disorders (upset) includes paralysis and
 Paralysis is inability of motor activity,
 Paresis is partial loss of motor activity.
Congenital anomaly of development
inflammatory diseases,
 affection of neural system due to
 - infections,
 - metabolic disorders,
 - toxicosis.
The symptoms of neurological
disorders of different diseases can be
defects of speech,
defects of hearing,
defects of reading or writing,
extremely large head in
the small dimensions of cranial
in microcephaly
paralysis of facial nerve,
paralysis of peripheral nerve,
disturbance of coordination,
motor ataxia,
increased muscular tonicity,
decreased muscular tonicity,
pathologic reflexes.
Congenital hydrocephaly
According to spreading
it is possible to distinguish monoplegia,
hemiplegia, paraplegia, tetraplegia. According to
focus of movement neurone (effector neurone)
affection it is possible to make out
- central (spastic) paralysis due to affection of
central neurone
- and peripheral (flaccid) paralysis due to
affection of peripheral neurone.
Central (spastic) paralysis is
characterised by
 increase
of muscular tonus,
 increase of deep tender reflexes,
 pathologic reflexes (Babinsky’s reflex,
Rossolimo’s reflex).
 muscles tropism is not affected,
 atrophy is not present.
Peripheral (flaccid) paralysis is
 muscle
 decrease or absence of reflexes,
 extremities grew colder, trophic disorder,
decrease of bones growth are marked.
Most often reasons of paralysis and paresis
 pathology
of perinatal period,
 polyomielitis,
 metabolopathy.
Central paralysises are result of
 acute
and chronic affections of brain
 as in intrauterus period,
 so in delivery, if brain is affected
by asphyxia or trauma,
Convulsive syndrome (seizures)
Types of convulsions are various:
Clonic convulsions:
tonic convulsions – with affection of extenzors, flexors, mixed
type, unifocal, multifocal, hemiconvalsions,
focal tonic –asymmetrial truncal or eye deviation, generalized
tonic activity.
myoclonic (generalized or focal);
motor automatism (rhythmic rapid or random eye movements,
pedaling, rotatory arm movements, purposeless movements).
Causes of seizures are various:
infections of CNS –
infection diseases – dysentery, pneumonia, gastroenteritis and many
Syndromes of sensitivity disturbances.
Sensitivity can be
 increased,
is called hyperesthesia,
 decreased is called hypoesthesia.
 changed due to different diseases (meningitis,
tumor of brain) is called paresthesia
Meningeal syndrome occurs in all forms of acute meningitis
Symptoms of meningeal syndrome include all typical
brain affection symptoms and local symptoms.
Most typical symptoms are
fever, headache, vomiting, dizziness, muscle tonic strain, neck
muscle regidity, Kernig’s, Brudzinsky’s symptoms are positive,
Lesage’s symptom is positive, convulsions, sensitivity
disturbances (hyperesthesia), vegetative disturbances
(arrhythmia, pulse and breath dissociation), disturbances of
breath rhythm, vasomotor lability, psychiatric disturbances
(dullness, adynamia, hallucinations, hypomnesia).
Bulging fontanella, motor unrestless, convulsions, tremor of
extremitis, dullness, unconscionsness, change of CFS (protein
increase, leucocities increase, increased pressure) are typical for
newborn suffering from meningitis.
Encephalitic syndrome
includes some complexes of symptoms
general symptoms of infections (fever, hemogramme
changes, increased ESR),
symptoms of general brain disturbances due to oedema
and hyperaemia of brain, hyperproduction of liquor,
disturbances of consciousness, excitement convulsions,
meningeal symptoms, cells-protein dissociation in CSF.
Encephalitic reaction occurs in acute infections
(convulsive syndrome, delirium).
Syndrome of consciousness disturbances
excitement with euphoric,
excitement with negativism,
coma (I, II, III degree).
Cause of consciousness disturbances are
metabolic disorders,
diabetes melitus.
Syndrome of sleep disturbances
includes superficial sleep,
 insomnia,
 sleep walking (somnambulism),
 swing and
 knocking.
Syndromes of CNS disturbances
in newborn and infant includes syndromes of
motor disturbances,
muscle hypotonia,
muscle dystonia,
muscle hypertonia,
cerebellum motor disturbances,
hypertention – hydrocephalic syndrome,
convulsive syndrome,
syndrome vegetative-visceral disturbances,
syndrome of minimal brain dysfunction.
Neurosis in children
includes stammering,
 hysteria,
 noctural incontinence of urine (enuresis),
 tics,
 cramp,
 neurasthenia.
Care of children with nervous system disorder
Some pathological syndromes are accompanied disorders of vital
functions (breathing, cardiovascular activity) and demand intensive
care. Intensive care includes:
comfortable condition because neural regulation of vegetative
functions is not perfect if the child is suffering from serious
neurological disorders.
Incubator is advisable for newborn (temperature regime, humidity,
oxygen supply).
Monitoring of vital functions has to be done.
Fluid and electrolytes balance control.
Monitoring of IV fluid therapy is advisible.
Nutrition has parenteral feeding if it is necessary.
Care of children with nervous system disorder