Spasmolysis: A New Technique for Treatment of Spasticity: Preliminary Report

Abstract

ANDMuscle spindles, located within voluntary muscle, have been identified as sensory organs which play a major role in the control of muscular contraction during both motion and the steady state (1-3). These spindles are now believed to have a double motor as well as a double sensory supply (4). The muscle spindle, via its sensory fibers, supplies the central nervous system with information concerning the state of the muscles, while the fusimotor element of the spindle serves as a motor regulator of incoming sensory information. These fusimotor elements are part of the gamma motor system. Impulses from the primary sensory endings of the spindle excite the alpha motor neurons monosynaptically, thus supplying the basis of the monosynaptic reflex arc. By differentially damping or suppressing this monosynaptic reflex arc, it should be possible to lessen or abolish spasticity while preserving voluntary motor activity. This communication is a preliminary report of a new technique aimed at producing a differential block of the muscle spindle. The technique consists of perfusion of the isolated lower limb with 0.2 per cent phenol; this process diff erentially lyses the gamma fibers, which are more susceptible to this agent than are the larger motor or sensory fibers.The concept of differential necrosis within the central nervous system is not new. It is seen most notably in certain neurologic diseases. For example, poliomyelitis attacks the motor neurons of the spinal cord and brain stem while sparing the sensory elements. On the other hand, the virus of herpes zoster selects the sensory ganglion cells for its destructive attack, without molesting the motor neurons.Gasser and Erlanger ( 5 ) demonstrated that nerve fibers of various size differ in their response to various blocking agents. This finding led to the differential block of spinal nerve roots by procaine or phenol for the purpose of selectively inhibiting or destroying nerve fibers of small diameter (6, 7). Since both the large afferent fibers and the large motor fibers are more resistant to phenol block than are the small fibers of the gamma motor type, it should be possible to remove gamma activity differentially without materially affecting alpha motor function. Matthews (8) demonstrated such a selective effect with regard to the stretch reflex. Walshe (9), Rushworth (10) and others have reported a similar effect on parkinsonian rigidity.Selective intrathecal phenol block of spinal nerve roots was shown by Nathan (11) and by Landau et al. (12) to decrease spasticity. Kjellberg et al. (13) lessened