H-reflex as an index for the efficacy of spasticity

Spasticity is frequently observed after upper motor neuron lesions with unknown exact incidence. Yet, it nearly affects more than 12 millions individual worldwide. ment of spasticity is usually not directed at its complete removal but rather at improving limb function, alleviating pain or easing care. This study was performed on 31 normal control subjects (30 male and 1 female)with ages range from 21-66 years and 59 spastic patients (49 male and 10 female) due to traumatic spinal cord injury with an age range from 18-73 years. The patients were divided into 5 groups with considering that some patients were examined more than one time in a way that did not interfere with the results (some patients were examined before treatment and after taking the different types of treatment while other patients were examined during taking a
particular type of treatment) and as follows: Positive controls: included 12 patients who were not taking any type of treatment or performing a regular previous physical program. Group (I): included 31 patients who were subjected to a regular physical therapy program in a rate of 1 session/ ray. Group (II): included 30 patients who were taking the oral anti-spasticity drug (Baclofen) in its full therapeutic dose in addition to the previous physical therapy program. Group (III): included 33 patients who were subjected to Transcutaneous
electrical nerve stimulation (TENS) therapy applied to spastic lower limbs, lasting for 10 minutes once and were performing the same previous physical therapy program. Group (IV): included 15 patients who were taking the oral anti-spasticity drug (Tizanidine) 4 mg one dose and subjected to the same previous physical therapy program. The following test were performed Hb, PCV, Random blood sugar and renal function test and the following electrophysiological parameters: H-reflex latency, H-reflex conduction velocity, H-reflex duration, H max/M max ratio in addition to the F wave Latency. The H/M ratio was used as an index to assess spasticity in addition to the assessment of spasticity treatment response. The results showed that there was a highly significant difference between the positive controls and other treatment groups concerning the mean value of H max / M max ratio, but this ratio in group I and group III did not reach the healthy controls value in contrast to the other groups. On the other hand, there was no significant difference concerning other parameters between the healthy control subjects and patients. Because the SCI in this study was traumatic, there will be no reason that the peripheral nerve conduction velocity will be affected in those patients. So the Hreflex latency, H-reflex conduction velocity, H-reflex duration and the F wave Latency was not significantly different between the healthy controls and the patients. While the H/M ratio was increased in the positive controls due to the high motoneuronal excitability in upper motor neuron lesion that may be attributed to the loss of the supraspinal inhibitory control and similar impulses from interneurons.
In groups I and III, the H/M ratio was significantly decreased due to activation of a wide spectrum of afferents, including both cutaneous and muscular mechanoreceptors in the former group and activation of sensory Ia afferent fibers switching on presynaptic inhibition mechanisms in addition to the action of physiotherapy in the latter group that might decrease the motoneuronal excitability but both groups didn't reach the healthy controls value. Whereas In groups II and IV, the H/M ratio was significantly decreased that it showed no significant difference with the healthy controls due to the depression of the H-reflex by Baclofen because of its GABA agonistic activity causing a direct depression of motoneuronal excitability in the former group while the α2 agonistic activity of Tizanidine potentiates presynaptic inhibition, suppression of flexor reflexes, as well as its direct action on α-motoneurons in the latter group in addition to the synergistic action of physiotherapy in both groups causing reduction of spasticity In conclusion spasticity can be treated but a multidisciplinary approach is required since it is unusual for a single intervention to be the only modality
needed. In addition, H-reflex can provide information regarding neural function after spinal cord injury and the H/M ratio can be used as a good indicator for both spasticity assessment and response to treatment.
We recommend using the H-reflex parameters as a good research tool to assess the effectiveness of various spasticity treatment modalities in spinal cord injury and other upper motor neuron diseases. Additionally, further studies are needed to evaluate the effectiveness of long term TENS treatment and other
types of spasticity management that was not used in this study, and also to compare the Modified Ashworth Scale with the H-reflex parameters especially the H/M ratio.