Coma/Raised ICP Flashcards
Four main causes of coma
Supratentorial mass lesions
Infratentorial mass lesions
Metabolic encephalopathy
Psychogenic coma
What is needed to maintain consciousness?
One cerebral hemisphere and the brain stem RAS (failure of both hemispheres OR the brain stem RAS results in coma)
How can you try to reverse coma (3 reversible etiologies)
Naloxone
Thiamine
Dextrose
Decorticate posturing
Upper extremity flexion, lower extremity extension
Decerebrate posturing
Extension of all four limbs
Does flexion or extension imply higher level of brain functioning?
Flexion
Verbal responses in Glasgow Coma Scale
Oriented 5 Confused 4 Inappropriate words/ not coherent 3 No words, only sounds 2 None 1
Eye Opening in Glasgow Coma Scale
Spontaneously 4
To speech 3
To pain 2
None 1
Motor responses in Glasgow Coma Scale
Obeys commands 6 Localizes to pain 5 Withdraws to pain 4 Abnormal flexion 3 Abnormal extension (decerebrate) 2 None 1
Dose of thiamine that should be given in comatose pt who is receiving glucose?
100 mg IV
What do pupils look like in coma due to metabolic reason?
Small and reactive
What do pupils look like in coma due to a tectal lesion
Large, fixed, hippus
What do pupils look like in coma due to lesion in pons
Pinpoint pupils
What do pupils look like in coma due to a midbrain lesion
Mid position, fixed
What do pupils look like in coma due to CN III (uncal) lesion
Dilated, fixed
What do pupils look like in coma due to diencephalic lesion
Small and reactive
Vestibulo-ocular reflex (dolls eye reflex)
Reflex eye mvmt that stabilizes the image on the retina during head movements, such that eye moves in direction opposite to head movement in order to keep image in centre of retina - mediated by CN VIII and CN 3,4,6
What are the brainstem reflexes to check in comatose pt
Pupillary reflex Corneal reflex VOR dolls eye Caloric testing Gag reflex
In comatose pt, if you find asymmetric focal signs in CN exam what is next step in diagnosis and what do you suspect?
Order urgent non contrast head CT
- suspect structural cause of decreased consciousness such as stroke, abscess, tumor or ICH
Cerebral perfusion pressure
CPP = MAP - ICP
- normally > 60 torr
What cerebral perfusion pressure is considered “too low” and results in inadequate cerebral blood flow
< 40 torr
Uncal herniation
Ipsilateral CN III palsy
Contralateral hemiparesis
Central (transtentorial) herniation
Progressive rostral-caudal loss of brain stem function due to pressure on entire brain stem
Transfalx (subfalcial) herniation
May cause infarction of anterior cerebral artery that lies in interhemispheric fissure
