F- CLINICAL ASPECTS OF SPINAL CORD INJURIES
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relieving spasticity in paraplegia (Nathan, 1959; Kelly & Gautier-Smith, 1959; Liver-
sedge & Maher, 1960; O'Hare, 1962; Griffith, 1969; and others). It has been suggested
that the phenol injection can be used unilaterally and far more selectively as a chemical
rhizotomy in incomplete lesions than is possible with alcohol because of the hypobaric
value of alcohol. This can be achieved if the patient, following injection, is left for some
time and up to 2 hr lying on the side to be blocked. Animal experiments on the effect of
phenol (Nathan & Sears, 1960) showed a differential blocking effect of 5 per cent phenol
solution in myodil and 0-5 and o-i per cent aqueous solution on the various action
potentials, by stimulating peripheral nerves and recording from anterior and posterior
roots of the cat. These authors found that phenol blocks the various fibre groups of a
nerve root in the same order as do standard local anaesthetics, in that 'C Fibres are
blocked first and the fastest conducting 'A' Fibres are blocked last. When phenol solution
is placed in contact with a spinal root for a certain time, it may produce irreversible
block of 'C Fibres, while the block of Alpha Fibres is reversible. Weiss
et al.
(1966)
suggested that phenol may be so selective, that only the Gamma Fibres are interrupted.
However, these authors did not give any experimental proof of their statement.
Technique.
The patient is placed on the X-ray table lying on the side to be blocked and
tilted forward about 20° with a pillow placed under the pelvis. An X-ray is taken across
the table to ascertain how much tilt of the table is necessary to cover the desired area
with the phenol solution. O'Hara followed Kelley's procedure to sterilize the phenol in
glycerine, and 20 per cent concentration is selected to reach the anterior roots. The best
results were achieved following intrathecal injection of 1-5-2 cc of this solution. Cain
(1965) is using 7-5 to 10 per cent phenol in glycerine solution for the initial injection in
patients with complete cord lesions. Comparison of therapeutic results obtained using
equal concentrations of phenol in glycerine and phenol in pantopaque (R) or myodil
revealed greater relief of spasticity and longer duration of effectiveness using glycerine.
Liversedge & Maher (1960) attributed this difference of efficacy to a slower release of
phenol from myodil and to the globular emulsive form of pantopaque compared with
glycerine's direct contact with the spinal roots. However, Griffith (1969) preferred phenol
mixed with 5 cc of pantopaque, as it allows the injection to be performed under fluoro-
scopic control. The spinal roots treated by this solution are from Tio caudally. If the
patient is kept lying on his side for 6 hr the roots of the opposite side, as claimed by
Griffith, are not affected and the chemical rhizotomy remains confined unilaterally only.
Fair, good and excellent results in abolishing spasticity of the lower limbs with intra
thecal phenol injections have been reported by various authors. However, the writer does
not agree with the sometimes too optimistic views expressed regarding sparing bladder
and sexual function following 'selective' phenol injections, having regard to cases admitted
later to Stoke Mandeville with definite and long lasting bladder paralysis. The writer
agrees with Cain (1965) that very careful consideration must be given to patients with
incomplete spinal cord lesions, who have appreciation of sensation or motor control in
their lower limbs, and he recommends for these patients tenotomy, neurectomy or
peripheral nerve injection, in accordance with the writer's indication of intrathecal alcohol
blocks in incomplete lesions of the spinal cord.
