COMAVISITH DANTANARAYANA

GROUP 301

PLAN

• A BRIEF DEFINITION

• A BIT ABOUT THE RAS

• BACK TO COMA

WHAT IS A COMA?

• A PROFOUND STATE OF UNCONSCIOUSNESS.

• THE PATIENT IS ALIVE BUT UNABLE TO MOVE OR RESPOND TO STIMULI COMING FROM THE ENVIRONMENT.

• A PERSON IN A COMA - COMATOSE

RETICULAR ACTIVATING SYSTEM (RAS)

For a person to maintain consciousness two important neuro logical components must function:• CEREBRAL CORTEX• RETICULAR ACTIVATING SYSTEM (RAS)DAMAGE TO EITHER OR BOTH THESE COMPONENTS WILL LEAD TO THE DEVELOPMENT OF A COMA.

RAS• A SET OF CONNECTED NUCLEI IN THE BRAINS

OF VERTEBRATES WITH THE SOLE RESPONSIBILITY OF MAINTAINING CONSCIOUSNESS AND THE SARCADIAN RHYTHM.

RAS

IT GENERALLY INCLUDES THE FOLLOWING COMPONENTS:MIDBRAIN RETICULAR FORMATION, TEGMENTUM, MESENCEPHALIC NUCLEI, THALAMICINTRALAMINAR NUCLEUS AN D THE DORSAL HYPOTHALAMUS

CAUSES• Intoxication (Accounts for almost 25% of cases)

• Metabolic abnormalities

• Vehicle collisions

• Severe stroke

• Hypoxia

• Herniation

CLASSIFICATION• SUPRATENTORAL

• INFRATENTORAL

• METABOLIC

• DIFFUSE

HERNIATION

PATHOGENESIS• After infancy the skull bones are rigid.• Therefore, any additional, abnormal growth

would increase the Intracranial Pressure.Two common herniations:• TRANSTENTORIAL HERNIATION• SUBFALCINE HERNIATION

TRANSTENTORIAL HERNIATION

The medial temporal lobe is squeezed by a unilateral mass under the tent like tentorium that supports the temporal lobe. The herniating lobe compresses the following structures:• Ipsilateral 3rd cranial nerve (often first) and posterior

cerebral artery• As herniation progresses, the ipsilateral cerebral peduncle• In about 5% of patients, the contralateral 3rd cranial nerve

and cerebral peduncle• Eventually, the upper brain stem and the area in or around

the thalamus

GLASGOW COMA SCALE• It is always important to know the severity of

the coma, for the sake of analyzing the prognosis.

• Eye opening• Motor response• Verbal response

POSITION CORRELATES WITH THE LOCALIZATION OF THE LESION

EEG PATTERNS

PUPIL DEVIATION

• 3 – the deepest level of coma; total unresponsiveness

• 3-8 – severe injury• 9 – not in a coma, but not fully alert• 9-12 – moderate injury• 13-15 – mild brain injury, or loss of

consciousness for fewer than 20 minutes• 15 – full consciousness

PROGRESSIVE VEGETATIVE STATE• Some distinction between a coma and a

progressive vegetative state has to be made.• Some people incorrectly relate PVS to Brain Death.• Individuals in such a state have lost their thinking

abilities and awareness of their surroundings, but retain non-cognitive function and normal sleep patterns.

• A person in a vegetative state may be released to the family for home care.

A Progressive Vegetative State may often follow a coma.

• Return of a sleep-wake cycle with periods of eye opening and eye closing

• May moan or make other sounds especially when tight muscles are stretched

• May cry or smile or make other facial expressions without apparent cause

• May briefly move eyes toward persons or objects• May react to a loud sound with a startle• Unable to follow instructions• No speech or other forms of communication• No purposeful movement

COMMON CAUSE OF DEATH

Death is largely attributed to secondary infections that may follow:

• Mostly Pneumonia

• Aspiratory pneumonia

• Atelectasis of the lungs

• Bed sores

BARB-COMAIt is a Barbiturate induced coma.Barbiturate comas are used to protect the brain during major neurosurgery, and as a last line of treatment in certain cases of status epilepticus that have not responded to other treatments.

THERAPEUTIC HYPOTHERMIA

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