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12f thalamic syndrome - Coggle Diagram
12f
thalamic syndrome
The thalamic syndrome is a disturbance of emotional responses to
sensory experience.
causes
is produced by damage to posteroventral and
posterolateral nuclei as a result of thrombotic blockage of thalamogeniculate branch of posterior cerebral artery.
Symptoms and signs
In thalamic syndrome occur on the opposite side of the body. These include:
Sensory symptoms
due to involvement of posteroventral nucleus are:
a) Astereognosis
occurs due to loss of tactile localization, tactile
discrimination and stereognosis.
b) Thalamic phantom limb
i.e. patient is unable to locate the position of
limbs with closed eyes and searches for the limb in air.
This occurs due to loss of kinaesthetic sensations.
c) Thalamic overreaction
i.e. the threshold for pain, touch and temperature
is decreased and the sensations become exaggerated and disagreeable.
d) Amelognosis.
It is illusion felt by the patient that his/her limb is absent.
Motor symptoms
due to involvement of posterolateral nucleus are:
a) Ataxia
decreased muscle tone and profound muscular weakness occur due to damage to cerebellar afferents.
b) Involuntary movements
any of the following may be associated:
Involvement of fibres coming from globuspallidus leads to chorea (quick jerky movements)
or athetosis (slow writhing and twisting movements).
Intention tremors are usually associated with thalamic syndrome.
c) Thalamic hand or athetoid hand
refers to the abnormal posture of hand occurring in patients with thalamic syndrome.
It is characterized by moderate flexion of the wrist with hyperextended fingers.