Regulation Of Posture

Anisocoria, decorticate posturing, and decerebrate posturing, all are mentioned as the ominous signs of severe head injury so development of diabetes insipidus is the answer of choice by exclusion here.

Normally are equal in size, round and briskly reactive to light. Brain injury and pressure on the nerves leading to pupils can produce change in pupil size, shape and reacting to light and movement.

These changes can be correlated with the severity and type of brain injury.

A sudden enlargement (Dilation) of one pupil (anisocoria) is an ominous sighn that require immediate intervention.

This typically signals increased pressure on one side of the brain, causing the brain to shift downwards in the skull cavity (uncal or tonsillar herniation).

• Loss of the normal autoregulation of blood pressure and pulse, called the cushing’s reflex is a hallmark of severe brain injury or imminent crisis. This generally results in a sudden rise in blood pressure and a slowing of the pulse.
• A person with a moderate or severe TBI may have a headache that does not go away, repeated vomiting or nausea, convulsions, an inability to awaken, dilation of one or more pupils, slurred speech, aphasia (word- finding difficulties), dysarthria (muscle weakness that causes disordered speech), weakness or numbness in the limbs, loss of coordination, confusion,restlessness, or agitation.
• When the pressure within the skull (intracranial pressure, abbreviated ICP) rises too high, it can be deadly. Sign of Increased ICP include decreasing level of consciousness, paralysis or weakness on one side of the body, and a blown pupil, one that fail to constrict in response to light or is slow to do so. Cushing’s triad, a slow heart rate with high blood pressure and respiratory depression is a classic manifestation of significantly raised ICP.
• Anisocoria, unequal pupil size is another sign of serious TBI.
• Abnormal posturing, a characteristic positioning of the limbs caused by severe diffuse injury or high ICP, is an ominous.

Ans. is ‘c’ i.e., More dangerous than decerebrate lesion

Decortical Posture

o Also known as flexor posturing or Mummy baby

o Arms flexed/bent over chest, hand fisted, leg extended & rotated inward

o Damage to area in cerebral hemisphere, internal capsule, thalamus & upper part of brain.

o Decorticate posture is ominous sign of severe brain damage.

Decerebrate posture

o Also known as extensor posturing

o Extension of upper limb & lower limb (ELBOW EXTENDED)

o Indicates brain stem damage (Below level of red nucleus)

o Decerebrate posture is more ominous than decortical posture

Ans. is ‘d’ i.e., Exaggerated tendon reflexes

Answer is D (Decorticate rigidity):

Decorticate rigidity is not seen as a manifestation of uncal herniation. All other features form part of the spectrum.

`Herniation or coning’ is said to be occurring when part of the brain is forced through a rigid hole.

Ans. is ‘c’ i.e., Rigidity is less pronounced than decerebrate rigidity

A decorticate rigidity is made by removing the whole cerebral cortex but leaving the basal ganglia intact.

Decorticate rigidity is characterized by flexion of upper extrimities at elbow and extension of lower extrimities.

The flexion is due to rubrospinal tract excitation of flexors in the upper extrimities and hyperextension of the lower extermity has same mechanism as in decerebrate rigidity.

The decorticate animal does not have such intense hypertonia as decerebrate animal.

This is because the basal ganglia, which are intact in the decorticate animal, activate the descending inhibitory reticular formation, and thereby prevent excessive hypertonia.

Ans. is ‘b’ i.e., Long loop stretch reflex

Ans. d. Clasp-knife spasticity

• When the muscles are hypertonic, as in a UMN lesion, the sequence of moderate stretch —n muscle contraction, strong stretch —n muscle relaxation is seen.
• Passive flexion of the elbow meets immediate resistance as a result of the stretch reflex in the triceps muscle.
• Further stretch activates the inverse stretch reflex. The resistance to flexion suddenly collapses, and the arm flexes.
• Continued passive flexion stretches the muscle again, and the sequence is repeated.
• This sequence of resistance followed by a ‘give’ when a limb is moved passively is known as the clasp-knife effect because of its resemblance to the closing of a pocket knife.

It is also known as lengthening reaction because it is the response of a spastic muscle to lengthening