coma dr d v siva kumar asso professor gen medicine
TRANSCRIPT
COMA
Dr D V Siva KumarAsso ProfessorGen Medicine
Definitions :
o Consciousness – is a state of Cerebral activity in which patient is aware of both self and environment and able to respond to internal changes
o COMA is a state in which patient makes no Psychologically meaningful response to the external stimulus or inner need
o Dementia- Patient is awake and alert but muddled in time place and person (confusion) and as impaired memory and mental processing
o Delirium – patient is similarly confused but alertness is impaired (drowsy)
o Acute confusional state in which patient alertness is clouded and associated with agitation, fright, and confusion
Causes of COMA
Metabolic
i. Hypoglycaemia
ii. Diabetes mellitus
iii. Renal failure
iv. Hepatic failure
v. Hypothermia
vi. Hypothyroidism
vii. Cardio respiratory failure
viii. Hypoxic encephalopathy
o Drug overdosage (including alcohol)
o Structural
- Diffuse
i) Meningitis
ii) Encephalitis
iii) Other infections (e.g. cerebral malaria)
iv) Subarachnoid haemorrhage
v) Epilepsy
vi) Head Injury
vii) Hypertensive encephalopathy
Focal :
i) Supratentorial Lesions
ii) Cerebral Haemorrhage
iii) Cerebral infarction with oedema
iv) Subdural haematoma
v) Extradural haematoma
vi) Tumour
vii) Cerebral abscess
viii) Pituitary apoplexy
Subtentorial lesions :
i) Cerebellar haemorrhage
ii) Pontine haemorrhage
iii) Brainstem infarction
iv) Tumour
v) Cerebellar abscess
vi) Secondary effects of transtentorial herniation of brain due to cerebral mass lesions
Immediate assessment of coma: seven questionsQuestion Check ActionAirway Blood gases Intubate, clear ? give oxygen
2. Fittings? Blood glucose I.V glucose,I.V diazepam,oxygen
3. Signs of CT scan Neurosurgical
craniofacial opinion
trauma?
Question Check Action
4. Neck broken? Splint neck X-ray neck
5. Major Maintainhaemorrhage? circulation
6. Signs of Check blood Treat Diabetes and urine appropriately Mellitus? glucose
7.Evidence of Pupils / Naloxone? drug overdose ventilation
or misuse?
Basic neurological examination in coma
o Assess level of consciousness
o Signs of head injury
- Local bruising, fractures and penetrating wounds
- Bleeding from nose or ears
o Splint the neck: head injury may be associated with fracture of the cervical spine
o If no neck injury (Clinically & by X-ray) check for neck stiffness
o Check resting pupillary size, and pupillary responses to light
o Ocular movements: spontaneous, following and to “doll’s head” (if no voluntary response)
o Limbs: posture, tone and movement
o Reflexes and plantar responses
o Fundi
Metabolic and drug – induced coma
o Coma without localizing signs is characteristic syndrome
o Full range of ocular movement to “doll’s head” testing
o Pupils may be small, e.g. opiate poisoning
o Altered respiratory pattern may signify metabolic acidosis (consider diabetic coma), or respiratory alkalosis (with hypercapnia)
Decerebrate extension may occur in extremis
o Look for signs of metabolic disorder, e.g. jaundice, uraemia, respiratory failure, hypocalcaemia, endocrine disease (especially hypothyroidism or hypopituitarism)
o Drug-induced coma is associated with access to medication or drugs of abuse, or signs of repeated venous access
o Pre-conditions for considering diagnosis of brain death
o The Patient is deeply comatose
a) There must be no suspicion that coma is due to depressant drugs
E.g. Narcotics, Hypnotics, Transquilisers
b) Hypothermia must be excluded Rectal temperature should exceed 350 C
c) There is no profound abnormality of Serum electrolytes, acid base balance, blood glucose concentration and any endocrine metabolic cause of coma has to be excluded
2) Spontaneous respiration has been inadequate or ceased.
Patient is maintained on ventilator, drugs, including neuromuscular blocking drugs should be excluded as cause of respiratory failure
3) The diagnosis of the disease leading to brain death has been firmly established. They should be no doubt the patient is suffering from irremediable structural brain damage
Test for confirming Brain Death
o The pupils are fixed and unreactive to light.
o The corneal reflexes are absent
o Vestibul ocular reflexes are absent
o No motor responses to adequate stimulation
o There is no gag reflex and no reflex response to suction catheter in the trachea
o The test usually repeated after the interval of 6 to 24 hours depending on clinical circumstances before brain death is confirmed.
o History
o General Examination
o Neurological Examination
Examination of unconscious patient
History :
o Questioning relatives, friends or ambulance teem is an essential part
o As the patient sustain head injury
- Leading to admission (or)
- Preceding weeks
o Did the patient collapse suddenly.
Did limb twitching occurred
o Have symptoms occurred preceding weeks
o Does patient suffered a previous illness.
o Does patient take medication
Neurological Disease can produce systemic signs or a systemic disease may affect nervous system.Temperature evidence of weight loss Septic causeBP breast lumps Skin marksNeck stiffness Lymphadenopathy RashesPulse irregularity Hepatosplenomegaly café – au – lait spotsCarotid bruit Prostatic enlargement angiomataCardiac mumurCyanosisLook :Signs of head injuryNeedle marks on armsEvidence of tongue bitingSmell of alcohol
General Examination
Glasgow coma scale (GCS)
o 1974 Teasdale and Jennett, in Glasgow, developed the system for conscious level assessment. They discarded wage terms such as stupor, semi coma and deep coma, and described conscious level in terms of
- EYE opening
- VERBAL response
- MOTOR response
- GCS serves immediate prognostic guide
Eye opening Verba response Motor response
Spontaneous-4 Orientated – 5 Obeying commands-6
To speech – 3 Confused – 4 Localising - 5
To pain - 2 Words – 3 Normal Flexion – 4
None – 1 Sounds – 2 Spastic Flexion – 3
None – 1 Extension – 2 None – 1
o Always describe the conscious level in terms of the actual responses i.e. no eye opening no verbal response and extending
o Also examine
o Pupil response
o Optic Fundi
o Corneal reflex
Limb :
o Reflexes
- Tone
- Plantar response
Eye Movements
o Observe any spontaneous eye movements
- Elicit the oculocephalic (Doll’s Eye) reflex
- Rotation or flexion / extension of the head in comatose patient produces transient eye movements in a direction opposite to the movement
- Note whether the movements, if present, are conjugate or dysconjugate. These ocular movements assess midbrain and tontine function.
- Elicit the oculovestibular reflex (Calorie testing)
o In a comatose patient, irrigation of the external auditory meatus on one side with at least 20ml of ice cold water induces slow conjugate deviation of the eyes towards the irrigated side after a few seconds delay
o In the awake or drowsy patient this slow tonic deviation is masked by a fast, coarse nystagmus towards the opposite side
o Visual fields
o Facial weakness
o Limb weakness
- If pain produces an asymmetric response, then limb weakness is present