CHAPTER 22
PATTERNS OF REFLEX DISTURBANCES
In the following, both the stage of spinal shock and the various stages of reflex automism
will be discussed in detail:
A. Stage of spinal shock
Since Marshall Hall (1841) introduced the term 'spinal shock' for the state of a transient
in—or hypoexcitability of, the isolated cord which exists immediately and in the early
stages following partial or complete transection of the spinal cord, this phenomenon
has been the subject of very extensive clinical and physiological research and discussion.
While the majority of modern investigators hold the view that spinal shock represents
a dysbalance of the function of the internuncial neurons and not of the motor neurons,
the intrinsic mechanism of this phenomenon and its variations amongst the various
species in the evolutionary scale is still not fully understood. One of the reasons for this
is the fact that experimental workers in this field adopted different technical procedures
and modes of investigation, including different types of anaesthesia. This is in particular
the case when the functions of the spinal cord have been studied in preparations of
animals of higher grade in the evolutionary scale. Koley's & Muckerjee's (1964) comments
on the techniques used are as follows:
1
Sherrington's preparations were not a spinal preparation, but a decapitate preparation.
2 The technique of pithing the cord used by Goltz (1869) is suitable only in small
animals such as frogs and guinea-pigs. His theory that spinal shock is due to stimulation
of the cut stump of the cord was challenged by Sherrington as unproven and is now
generally rejected.
3
Treat's technique (1941) used in cats by blind puncture and cauterization, avoiding
traumatic effects of laminectomy, has the uncertainty of complete separation of the
cord.
4 McDowall's technique adopted more or less by Downman, McSwiney and Muckerjee
himself is a preparation which converts the preparation into 'decerebrate with cordotomy'.
Artificial respiration was always required to maintain the life of the animal.
To the techniques of these workers may be added that of Barnes
et al.
(1962) who
measured the resting potential of cells in the lumbar segment of the spinal cord of the
cat before, during and after the cord was functionally blocked by cooling with OC brine
passed through a copper tube surrounding the cord at mid-thoracic level. They came to
the conclusion that the physiological derangement in spinal shock is a hyperpolarization
ofmotor neurons. The authors consider this as a result of random synaptic bombardment
by nerve endings, either directly or indirectly activated from more cephalad regions,
which normally keep the cells in slightly hypopolarized state.
However, whatever the techniques and the experimental results in animals may have
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