F- CLINICAL ASPECTS OF SPINAL CORD INJURIES
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(2)
Latent period between time of cord transection and spinal shock
In analysing various factors involved in spinal shock in man, there is first the question
whether the sudden withdrawal of the innervatory influence from supraspinal centres as
the result of partial or complete cord transection disrupts the transmission at the synapse
hi the segments caudal to the lesion immediately or whether the ganglion cells at the
synapse still retain their charge of energy and excitability for a short period and are thus
capable of maintaining for a while the process of conduction. I have found the ankle
jerks, plantar response and, in particular, anal sphincter and bulbo-cavernosus reflexes
to be still present immediately after cord transection and they may disappear only after a
certain latent period, while the anal reflex may not disappear at all. It is well known that
immediately after decapitation in man by guillotine, as practised not long ago in France,
the knee jerks are still elicitable for several minutes (Barre, 1915). In this connection, it
may also be remembered that Collier (1916, 1917) succeeded in the first days following
cord transection in eliciting the initially abolished knee jerk following faradization of the
quadriceps for 5-15 min. These observations of clinical neurologists of the old
school are today of particular interest in the light of modern physiological research on
spinal shock, as they indicate that the sudden withdrawal of the excitatory influence of
supraspinal centres and their descending tracts on the transmitting synapses in the stage
of spinal shock can be temporarily obviated by strong peripheral afferent impulses.
Conversely, Foerster (1908, 1911) proved the importance of the afferent system on the
reflex activity of the spinal cord by dividing the posterior roots resulting in distinct
though, according to number of divided roots, variable degree of reflex depression. All
these observations have been invaluable in furthering our knowledge in the mechanism
of spinal shock in the spinal man. There is no doubt that neurological examinations at
frequent intervals by the same examiner during the immediate and early stages following
complete as well as incomplete traumatic lesions of the spinal cord are of utmost import
ance in determining intensity, duration and site of spinal shock as well as evaluating the
intricacy and variability of reflex return in the spinal man. Therefore, the need for
accurate records cannot be overstressed, the more so as the modern student can now
approach this subject with more sophisticated methods of investigation than the investi
gator of the past.
(3)
Intensity and duration of spinal shock
It is now generally agreed that intensity and duration of spinal shock increase commen
surate with the vertebrate scale, especially in the primate species. The higher the cerebral
development the deeper the spinal shock. A comparison of different species reveals a
striking parallel between the degree of development of suprasegmental structures and
their descending tracts and the intensity and duration of the spinal shock resulting from
the cord transection. Sherrington found it impossible to elicit the knee jerks for about a
month in the case of a monkey, whilst in a rabbit its absence lasted only 10 to 15 min.
In lower species, reflex activity may even occur without delay after severance of the cord.
Fulton & McCouch (1937) found that in the Erythrocebus group of monkeys all reflexes
