NeuroTeach 44 - The examination in Coma

 The Examination in Coma

“the father of modern neurological surgery”

American neurosurgeon Harvey Williams Cushing (1869–1939)


2) Definition
“a state of unarousable unresponsiveness” Parts a. level of consciousness b. vital signs (BP & breathing pattern) c. cranial nerves (fundoscopy + vision + brainstem) d. motor & sensory e. reflex f. meningeal signs

3) Level of consciousness
Normal Clouding of consciousness Confusion/delirium Lethargy Obtundation Stupor Coma


4) Grading level of consciousness
GCS (Glasgow Coma Scale) RASS (Richmond Agitation-Sedation Score) FOUR (Full Outline of UnResponsiveness)

5) GCS (Glasgow Coma Scale)
- Parameters: best eye response, best verbal response, and best motor response - Values between 3 and 15 - Mnemonic: EYES, VOICE, OLDBEN


6) RASS (Richmond Agitation-Sedation Score)
- mostly used in mechanically ventilated patients to avoid over and under-sedation


7) FOUR (Full Outline of UnResponsiveness)
- eye responses, motor responses, brainstem reflexes, and breathing pattern


FOUR instructions


8) Vital signs
a. pulse & blood pressure - Cushing triad of increased intracranial pressure (hypertension + bradycardia + irregular breathing) b. breathing pattern

9) Breathing pattern
“special attention to the breathing pattern, as some patterns help us localize lesions” Breathing pattern rules 1st higher injury results in faster breathing 2nd higher injury results in more organized patterns 3rd injury to the ‘p’ons results in ‘p’auses


10) Cheyne-Stokes respiration
“Hyperpnea regularly alternating w/ apnea” - bilateral cerebral dysfunction - increased ICP - decreased cardiac output

11) Central neurogenic hyperventilation
“w/ respiratory alkalosis” - damage to rostral brainstem tegmentum paramedian pontine reticular formation - stimulation of afferent peripheral reflexes in lung and chest wall


12) Apneustic breathing
“prolonged pause at the end of inspiration” - lateral tegmentum of the lower half of the pons

13) Cluster breathing
“periodic respirations that are irregular in frequency and amplitude with variable pauses between clusters of breath” - lower pontine tegmental lesion


14) Ataxic breathing
“irregular in both rate and tidal volume” - medullary damage (reticular formation of dorsomedia medulla down to obex)

15) Kussmaul breathing
“deep and labored breathing pattern” - metabolic acidosis (diabetes ketoacidosis) in MA, breathing is 1st rapid&shallow but as acidosis worsens, breathing gradually becomes deep&labored (this latter type is aka Kussmaul)


16) Agonal breathing
“labored breaths, gasping, and, often, myoclonus and grunting” - lower brainstem damage

17) Respiratory center
“Boat starts and PRASaD DIVEs”

18) Cranial nerves
“fundoscopy + vision + brainstem reflexes” Fundoscopy a. bilateral papilledema - high ICP b. intraocular hemorrhage - high ICP due to subarachnoid hemorrhage (Terson syndrome)


19) Vision and eye movements
Vision - blink-to-threat Eye movements - ocular bobbing - ping-pong - forced downward gaze - rapid VOR w/ downward movement - ocular myoclonus

20) Brainstem reflexes
Brainstem Reflexes Assessment Sedation Scale (BRASS) i. cough reflex ii. pupillary light reflex iii. corneal reflex iv. absence of grimacing and absence of oculocephalic v. absence of grimacing and presence of oculocephalic


21) Pupil size
Small & reactive: metabolic and diencephalic Large & fixed & hippus: pretectal Dilate & fixed (unil): III nerve (uncal) - Kernohan notch Midposition & fixed: midbrain Pinpoint: pons


22) Motor & sensory exam
a. can the patient localize to painful stimuli? - defend, localize, withdraw, flex, extend, no response


23) b. movements in coma
- arc de cercle - choreiform fidgets - myoclonus status epilepticus - spontaneous triple flexion responses


24) c. posturing
decerebrate and decorticate


25) Reflexes
“the same as in the conscious person” - muscle tone - reflexes - clonus - plantar response

26) Meningeal signs
a. Nuchal (cervical) rigidity b. Kernig's sign c. Brudzinski's neck sign d. Brudzinski's contralateral reflex sign e. Tripod or Amoss's or Hoyne's sign f. Others

27) Differential
1.Coma w/ focal or lateralizing signs - CVA (ischemic or hemorrhagic) - Trauma - Space occupying lesion (tumor or infectious) 2.Coma w/ meningismus - Meningoencephalitis - Subarachnoid hemorrhage 3.Coma w/o localizing signs or meningismus - TOMES mnemonic


28) Coma mimicking
a. locked-in syndrome (video) - vertical eye movements and blinking are usually spared - awake


b. abulia & akinetic mutism - profound failure of executive function

c. hypokinetic catatonia
- obtundation - immobility, mutism, staring, cataplexy - Bush-Francis Catatonia Rating Scale d. functional unresponsiveness - open the eyelids (tightly shut eyelids; eye movements; rapid eyelid closure) - oculocephalic reflex - optokinetic nystagmus