Brain Death!
Christ's raising of Lazarus, Athens, 12–13th century
2) Definition & pathophysiology
Definition: Irreversible state
Pathophysiology: Complete circulatory arrest of the brain
- leading to intracranial compartment syndrome
3) General algorithm
a. clinical suspicion: catastrophic brain injury & cardinal findings
b. exclude confounders
c. AAN 2023 checklist
d. neuro exam + apnea test
e. ancillary tests
4) Cardinal features
- coma
- no cranial nerve function
- no respiratory drive
5) Confounders
Brain death mimickers
- neuromuscular paralysis
- hypothermia
- drug intoxication
- C-spine injury
- locked-in syndrome
Spinal reflexes
6) AAN 2023 Checklist
7) Neuro exam w/ apnea test
- Coma
- Absent brain-originating motor response
- Absent brainstem reflexes
> corneal reflex
> oculocephalic & oculovestibular reflex
> jaw jerk
> gag reflex
> cough w/ tracheal suctioning
> sucking or rooting reflexes (in neonates)
- Apnea test
8) Ancillary tests
Brain blood flow
a. Cerebral angiography
b. TCD
c. CTA
d. Nuclear medicine
e. MRA
Electrophysiology
a. EEG
b. Potentials: SSEP and BAEP
Others
a. Atropine
b. PaO2 in RA versus jugular bulb
* For the AAN, only DSA, TCD, and nuclear study (radionuclide angiography and radionuclide perfusion scintigraphy)
Reverberating TCD flow pattern
- Multi-depth power-motion (upper) & single-depth spectral analysis (lower) show reverberating flow in the vertebral artery by forward flow in systole (long arrow) followed by abrupt flow reversal in diastole (short arrow)
9) Spinal reflexes
- BD leads to disinhibition of spinal reflexes
- most common is triple flexion
- diff from volitional movements
> trigger by stimulus below the foramen magnum
> repeatable
> myokymia (not grimacing)
10) Decerebrate-type movement
- spontaneous extension of the extremities
11) Eyelid opening
- nipple stimulation
- stereotypic partial eye-opening with sternal rub or trapezius pinch but not with supraorbital or nailbed pressure
12) Fasciculation
13) Head-turning
- lateral head rotation arises primarily from activity of the spinal portion of the accessory (XI cranial) nerve and the cervical spinal cord
14) Hugging movement
Flexion of the trunk and movement of the arms in a hugging-like manner
15) Finger flexion
16) Lazarus sign
- reflexive movement seen after or near brain death (BD) w/ arms raising & dropping to chest
Lazarus sign
Lazarus sign
Lazarus sign
Signs of Lazarus
1. hallux flex lead movements of the fingers and contraction of the anterior tibial muscle
2. plantar stimulus cause disorganized flex of fingers
3. plantar stimulus cause flex of hallux, inversion of ankle and triple flexion response.
17) Plantar flexion
- Plantar flexion with noxious dorsal foot stimulation
18) Myoclonus
19) Facial myokymia
20) Respiratory-like movements
- Adduction of both shoulders followed by a slow cough-like movement
21) Triple flexion reflex
Flexion of the thigh, leg and foot
Triple flexion reflex
22) Thumbs Up Sign
23) Undulating toe flexion
24) Reflex of the Gracilis
Gracilis muscle, innervated by the obturator nerve, originates from the L2–L4 spinal nerve roots and may have contracted through an efferent pathway
25) Neck-abdominal reflex
- Anteflexion of the neck causes abdominal reflex
- Lazarus phenomenon