Friday, March 7, 2014

Can a patient make a movement and still meet criteria for brain death?


Spinally mediated reflexes and automatisms can be present in the setting of brain death. These movements are often misinterpreted by laypersons as signs of purposeful brain function. Careful neurologic examination can differentiate between reflexive movements and purposeful motor movements.

These are non-purposeful movements released by lack of descending inhibition of primitive spinal motor reflex pathways.

·         Deep-tendon reflexes: For example, Achilles, patellar, and biceps are by definition monosynaptic spinally mediated reflexes and hence often preserved despite brain death.

·         Abdominal reflexes: Deviation of the umbilicus toward a light stroking of the skin. Often preserved in brain-dead patients, it may be absent in normal or obese patients.

·         Triple flexion response or limb posturing: Stereotyped, non-purposeful flexion or extension and internal rotation in response to noxious stimulus. (A movement may be purposeful if the limb reliably moves away from, rather than toward, an applied noxious stimulus.)

·         Lazarus sign: Considered a variant of opisthotonus. It consists of extensor posturing of the trunk, which may look like chest expansion, simulating a breath. It may be accompanied by raising and crossing of the arms in front of the chest or neck. This sign most often occurs in the setting of apnea testing or disconnection from the ventilator. Hence it may be upsetting for family members or health care providers to witness this reflex.

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