Spinal Cord Reflexes and Surgery
The CNS structures essential to the definition of brain death
do not include the spinal cord. Histologic studies have shown that the spinal cord
is the best preserved part of the CNS in cases of brain death, and results have ranged
from grossly normal histology to edema, neuronal loss, neurolysis, and rarely, infarction.
[17]
However, the first cervical segment of the
spinal cord (C1) or the junction of C1 and the caudal medulla oblongata is the most
severely damaged. Because this is the site of herniation of the cerebellar tonsils,
the blood supply is easily cut off by compression of the anterior and posterior spinal
cord and vertebral arteries.[84]
Spontaneous and reflex movements are found in brain-dead patients.
Spontaneous body movements may be observed during the apnea test, while the body
is being prepared for transport, at the time of a skin incision for the retrieval
of organs, or in synchrony with the respirations produced by the mechanical ventilation.
[1]
In 5 of 60 cases of brain death after terminally
turning off the ventilator or during apnea tests, Ropper[62]
reported bizarre, seemingly purposeful movements of the upper extremities,
Figure 79-2
A, The patient 2 minutes
before the onset of movements. Beginning in B, photographs
are taken at approximately 5-second intervals 6 minutes after removing the ventilator.
B, The arms are brought rapidly to the sternum, with
the wrists remaining limp. C, The arms are then raised
above the body several inches, and the wrists are brought to a neutral position.
D, Over approximately 2 seconds, the hands are brought
together by shoulder adduction and held for approximately 5 seconds. E,
The position is released, and the elbows are extended to bring the limbs back to
the bed. The head and torso showed no movement. (From Ropper AH: Unusual
spontaneous movements in brain-dead patients. Neurology 34:1089, 1984.)
called the Lazarus sign, which the arms flexed quickly
to the chest from the patient's side, the shoulders adducted, and in some patients,
the hands crossed or opposed just below the chin ( Fig.
79-2
). Saposnik and associates[85]
reported
that 15 (39%) of 38 patients who fulfilled criteria for brain death showed spontaneous
or reflex movements; the most common movement was finger jerks, and the undulating
toe flexion sign, triple flexion response, Lazarus sign, pronation-extension reflex,
and facial myokymia also were seen. Health care staff should remember that the patient
moves in response to noxious stimulation and that full curarization is required for
surgical procedures involving brain death.
