Transcript 5742e03d8e0a593

Practical CNS
Sensory System Examination
Motor System Examination
Examination of Coordination
(Cerebellum)
Sensory System Examination
Sensation
Touch:
-Crude
-Fine Touch:
-Tactile localization
-Tactile discrimination
-Stereognosis
Pain
Proprioception:
Tool
used
Receptor
-Cotton
wool/brush
-Cutaneous
mechanoreceptors.
-Anterior
spinothalamic tract
-2 marker pens
-compass
- Familiar objects
-cutaneous mechano.
-Cutaneous mechano.
-Cutaneous mechano.
- Dorsal Columnmedial lemniscal
system.
Pin
Free nerve endings
-Lateral
spinothalamic tract
Joint of patient
Proprioceptors
- Dorsal columnmedial lemniscal
system
Two test tubes
Free nerve endings
-Lateral
spinothalamic tract
-Sense of position
-Sense of movement
Temperature
Tract
Stereognosis: The ability to identify
common objects by feeling them, with
eyes closed, it is a complex sensation
based on the synthesis of many
sensations, such as touch, pressure,
temperature..etc.
Proprioception:
Arise from stimulation of receptors within
the body tissues and include sense of
position and movement.
Static proprioception: awareness of
location of different parts of the body (body
image).
Kinesthetic proprioception: perception of
the rate of movement of different parts of
the body.
Motor System Examination
1. Inspection of muscle state
Inspection means using one’s vision.
The abnormal muscle states include:
Atrophy.
Hypertrophy.
2. Muscle tone (passive movement)
Here you have to notice resistance:
Normotonia
Hypotonia: e.g. poliomyelitis and spinal muscular
atrophy.
Hypertonia :
Rigidity (cog-wheel) : e.g. Parkinson disease.
Spasticity (clasp- knife) : e.g. Upper motor neuron
lesions.
3. Muscle power (active movement).
4. Superficial reflexes :
Planter reflexes.
Abdominal reflexes.
Cremasteric reflexes.
The flexor planter reflex
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The subject is asked to relax the muscles of the
legs.
A light scratch is given with a thumbnail, a key
or the blunt point of the patellar hammer, along
the outer edge of the sole of the foot, from the
heel toward the little toe, and then medially
along the base of the toes up to the 2nd toe.
Response: planter flexion and drawing together
of the toes, often including the big toe,
dorsiflexion and inversion of the ankle, and
sometimes contraction of the tensor fascia lata.
With stronger stimuli the limb may be withdrawn.
Afferent (tebial n.): L5,S1-2.
Center: S1-2.
Efferent (tebial n.): L4-5 segments.
Extensor planter reflex
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In infants: the response is a
dorsiflexion of the big toe and
retraction of the foot and occasionally
dorsiflexion and fan-like spreading of
the other toes.
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In adults, such a response is seen in
lesions of the corticospinal system.
This abnormal response is called
Babinski sign or positive Babinski.
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In this response the dorsiflexion of
the toes is followed by dorsiflexion of
the ankle and flexion of the knee and
hip.
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Note: the stimulus must be applied
over the lateral region of the sole
because the medial region may give
normal response.
 Babinski sign may be seen in the following:
 Infants below the age of 1 year, i.e., until the corticospinal
tracts get myelinated and become functional. The planter
response becomes flexor in the next 6-8 months when the
child learns to walk.
 Upper motor neuron (UMN; corticospinal or pyramidal)
lesions: such as cerebral vascular disease.
 Spinal cord tumors: the pyramidal fibers are very sensitive
to pressure, hence their early involvement in such cases.
 Coma due to any cause.
 Biochemical disturbances: such as hypoglycemia, in which
convulsions may occur.
Abdominal reflexes
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The subject should be relaxed and in supine position with the abdomen
uncovered.
A light scratch with a key or blunt point, is given across the abdominal skin,
directed toward the umbilicus, in the upper, middle and lower regions.
Response: a brisk ripple of contraction of the underlying muscles.
Centers:
 Upper abdominal : T8,9,10
 Middle : T9,10,11
 Lower abdominal : T10,11,12 segment of the spinal cord.
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These reflexes are absent in : UMN lesions above their segmental level in the
spinal cord. They may indicate the segmental level of thoracic spinal cord
lesion by their absent.
They are difficult to elicit in obese, elderly, anxious subjects and after repeated
pregnancies due to loss of muscle tone.
Cremasteric reflexes
a superficial reflex observed in human
males.This reflex is elicited by lightly
stroking the superior and medial (inner)
part of the thigh. The normal response is a
contraction of the cremaster muscle that
pulls up the scrotum and testis on the side
stroked.
5. Deep tendon reflexes
Stimulus: sudden stretch of the muscle
spindles, which sends a synchronous
volley of impulses from the primary
sensory endings into the spinal cord.
In the cord these impulses directly
(monosynaptically) stimulate the anterior
horn cells which innervate the stretched
muscles.
 Important:
 It may be noted that it’s the spindle receptors not the
tendon receptors which are stimulated though the
hammer is struck on the tendon and not the muscle
belly. All muscles are somewhat excitable to direct
mechanical stimulation, which is a direct response and
not a stretch reflex. (The tendon receptors respond to
excessive stretch- as an inverse stretch reflex, when the
muscles relaxes suddenly)
Important stretch reflexes and their spinal
segments
Stretch reflex
Spinal segment
Biceps reflex
C5,6
Brachioradialis reflex
C5,6
Triceps reflex
C6,7
Patellar reflex (Knee jerk)
L3,4
Achilles tendon reflex (Ankle jerk)
S1,2
1. The Knee Jerk reflex
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Supine position:
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Legs are semiflexed, and the
observer supports both knees by
placing a hand behind them. The
patellar tendon is then struck
midway between the patella and
the insertion of the tendon on the
tebial tuberosity.
Sitting position:
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The subject is seated in a chair
and is asked to cross one leg over
the other or sit with both legs
dangling loosley over the edge of
the chair.
Cont…
 Response : extension of the knee due to
contraction of quadriceps femoris muscle.
 Afferent and Efferent paths: femoral
nerve.
 Centre: L3-4.
2. The Ankle Jerk
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Sitting position:
The examiner slightly dorsiflexes
the foot so as to stretch the
Achilles tendon (tendocalcaneous) and with the other
hand, the tendon is struck on its
posterior surface.
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Supine position:
Knee is semiflexed and hip is
externally rotated, the ankle jerks
are then tested as described
above.
Cont…
 Response: planter flexion of the foot due
to contraction of the calf muscles.
 Afferent and Efferent paths: Tibial
nerve.
 Centre: S1-2 segments.
3. The Biceps Jerks
 The subject’s elbow is
flexed to a right angle and
the forearm semipronated
and supported on the
examiners arm.
 The examiner then plases
his thumb on the biceps
tendon and strikes it with
the hammer .
Cont…
 Response: contraction of the biceps
causing flexion and slightly pronation of the
forearm.( If the patient is in bed, his forearm
may rest across his chest).
 Afferent and Efferent paths:
musculocutaneous nerve.
 Centre: C5-6 cervical segments.
4. The Triceps reflex
 The arm is flexed to a right
angle and is supported on
the examiner’s arm or can
be placed on their hips.
 The triceps tendon is then
struck just proximal to the
point of the elbow.
Cont…
 Response: extension at the elbow.
 Afferent and Efferent paths: radial nerve.
 Centre: C6-7
0
No evidence of contraction
1+
Decreased, but still present (hypo-reflexic)
2+
Normal
3+
Super-normal (hyper-reflexic)
4+
Clonus: Repetitive shortening of the
muscle after a single stimulation
Reinforcement of the reflexes
 The briskness of the deep reflexes varies
greatly from one person to person but it’s
hardly ever absent in health.
 Occasionally it may be very weak or even
appear to be absent.
 In such cases reinforcement (Jendrassik
maneuver)is employed.
Cont…
 This is done by asking the subject to
perform some strong muscular effort such
as clenching the teeth, or locking the
fingers of both hands as hard as possible
and then trying to pull them apart while
the examiner strikes the tendon.
 The reflex generally becomes evident.
Cont…
 Reinforcement acts by increasing the excitability of
the anterior horn cells due to “spilling” over of
impulses from the neurons involved in
reinforcement effort to the motor neurons of the
reflex.
 In addition, gamma motor neuron activity increases
the sensitivity of the spindle receptors to stretch. It
also, perhaps, acting by distracting the subject’s
attention.
Tendon reflexes are diminished (hyporeflexia)
in:
 Lesions involving afferent pathways.
 Anterior horn cells (e.g., poliomyelitis).
 Or efferent pathways.
Tendon reflexes are absent (areflexia)in :
 Spinal shock, e.g., sever injury to the
cord.
 Coma.
 Note: deep reflexes may be sluggish or
appear to be abolished in some healthy
individuals; reinforcement is employed in
these cases.
Deep reflexes are exaggerated (hyperreflexia)
in:
 UMN lesions above the anterior horn cells,
especially when the hyperreflexia is
unilateral, or accompanied by other signs of
UMN disease.
 Anxiety or nervousness.
 Hyperexcitability of the nervous system
(hyperthyroidism ) and tetanus.
Cerebellum Examination
1. Finger to nose test
With eyes open, have patient partially
extend elbow and rapidly tip of index finger
in a wide arc to tip of his nose.
In cerebellar disease, the action may have
an intension tremor.
2. Finger to Finger test
3. Heel to shin test
Patient places one Heel on opposite knee
and slides heel down the tibia with foot
dorsiflexion.
Movement should be performed
accurately.
In cerebellar disease, the arc of the
movement is jerky/wavering.
4. Gait
In cerebellar disease, the walk is
staggering/wavering or zigzag.
5. Arm-pulling test (rebound test)