F- CLINICAL ASPECTS OF SPINAL CORD INJURIES
297
In analysing the relationship of anterior and posterior roots to sudomotor function
it has been proved by Foerster (1936) that electrical stimulation of the peripheral end of
a divided anterior root always elicits marked sweating over a greater or lesser number
of dermatomes. However, when the corresponding peripheral end of the divided posterior
root was stimulated prior to the stimulation of the anterior root, vasodilatation occurred in
the cutaneous distribution of the posterior root but there was anhidrosis in that area. This
was confirmed by the starch-iodine technique in a patient suffering from intractable
pain due to cancer metastases in the pelvis where, before a bilateral cordotomy was
performed (Professor Foerster), the electrical stimulation of the peripheral end of the
divided 5th thoracic posterior root resulted in vasodilatation of the cutaneous distri
bution of this root. Electrical stimulation of the divided 5th anterior root elicited marked
sweating, which started in T6 dermatome and extended distally to Tio. Moreover, the
outburst of sweat also spread in cephalad direction involving T3/4 dermatomes. How
ever, there was anhidrosis in the cutaneous area corresponding, though slightly larger,
to the vasodilator area obtained previously by the electrical stimulation of the 5th posterior
root thus demonstrating inhibition of sudomotor function (Guttmann & List, 1928).
Although these effects of electrical stimulation of the distal part of the divided
posterior roots is undeniable, there still persists discrepancy of opinion amongst workers
in this field as to whether the posterior roots conduct true efferent nerve fibres, which on
stimulation evoke segmental vasodilatation and sudomotor inhibition. It was Stricker
(1876) who first demonstrated the vasodilatator effect following stimulation of posterior
roots in animal experiments, and his findings were confirmed by Werziloff (1896),
Bayliss (1901) and Dieden (1915) in animals and by Foerster (1924,1927) in man follow
ing electrical stimulation of a great number of the peripheral end of divided cervical,
thoracic, lumbar and sacral posterior roots. It was also found that the resection of cervical,
upper thoracic and lumbo-sacral posterior roots resulted in temporary hypothermia
of the arm and leg respectively. However, this disturbance soon disappeared and local
cutaneous thermal and mechanical stimuli elicited undisturbed vasodilatation. As far as
the sudomotor function was concerned, only temporary hyperhidrosis followed the
resection of several adjacent posterior roots. In fact, in one case following the resection
of the posterior roots of 1^5-85 on the right side by Foerster, the thermoregulatory sweat
test which I carried out several weeks later revealed an hypohidrosis over the whole
posterior aspect of the right leg. Although no definite conclusion could be made from
this single case, the possibility that this hypohidrosis was the result of transneural
degeneration of ganglion cells in the corresponding intermedio-lateral autonomic centres
of the spinal cord could not be excluded (Guttmann, 1930).
In connection with the vasodilator and inhibitory sudomotor effects following
electrical stimulation of posterior roots, which suggest efferent function of fibres within
these roots, the anatomical studies of Ken Kure and his co-workers in animals (1930)
and Gagel (1930) in man may be mentioned. These authors described intact myelinated
nerve fibres of thin calibre in the central part of the divided roots and, moreover, Gagel
found degeneration of these fibres in the peripheral part of these roots at later stages.
From these findings, he thought to prove the existence of efferent nerve fibres in the
posterior roots originating from the intermedial cells of the lateral horns. Foerster
