Excitability relationships between lower limb myotatic arcs in spasticity.

Delwaide, P. J.; Cordonnier, Monique; Gadea-Ciria, M.

doi:10.1136/jnnp.41.7.636

Cited by 7 publications

(1 citation statement)

References 12 publications

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“…1 Electrophysiological recording of the H reflex 2 and determination of the ratio of the maximum amplitude of this reflex response (Hmax) over the maximum amplitude of the direct motor response (Mmax) measures the excitable fraction of the spinal cord motoneuron pool participating in the myotatic reflex. [3][4][5][6][7] An increase in the Hmax/Mmax ratio greater than 0.5 indicates that more than one half of the motoneuron pool is excited by stimulation of afferents derived from this muscle. It is considered to accurately reflect excitability of the motoneuron pool of the muscle recorded.…”

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Long term course of the H reflex after selective tibial neurotomy

Roujeau

2003

Journal of Neurology, Neurosurgery & Psychiatry

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Objectives: This study was conducted to evaluate the long term clinical and electrophysiological outcome by recording the H reflex in a consecutive series of six patients treated by selective tibial neurotomy for spastic equinus foot. Method: The amplitudes of Hmax reflexes, Mmax responses, and Hmax:Mmax ratio were recorded in six patients with chronic lower limb spasticity, before and after surgery, at day 1 and 8 months and 24 months after selective tibial neurotomy. The passive range of movement, the stretch reflex score according to the Tardieu scale, the osteoarticular and tendon repercussions, and the quality of motor control of dorsiflexion were evaluated preoperatively and postoperatively. Results: At the end of the study, all patients presented a reduction of equines. Gait and Tardieu's score of spasticity had improved in all patients. Active dorsiflexion of the ankle was unchanged in four patients, but two improved by 5°to 12°. In five cases, fascicular resection of the superior nerve to soleus was, alone, sufficient to reduce spastic equinus foot, without recurrence, for a mean follow up of 28 months. Two patients were reoperated on, one for remaining spasticity related to an underestimated spasticity of the gastrocnemius muscles, and the other for painful claw toes. Hmax, Mmax, and Hmax:Mmax ratios were significantly lower the day after surgery. The reduction of Hmax and Hmax/ Mmax ratio remained stable over time and was still statistically significant two years after the operation. However, the value of Mmax eight months postoperatively was no longer significantly different from the preoperative value. Conclusion: This study shows the long term efficacy of the selective tibial neurotomy as treatment of spastic equinus foot. Neurotomy confined to fibres supplying the soleus muscle is sufficient in most cases and acts by decreasing sensory afferents without significant long term motor denervation. S pasticity is defined as hyperexcitability of the myotatic reflex causing velocity dependent exaggeration of the stretch reflex and deep tendon reflex.1 Electrophysiological recording of the H reflex 2 and determination of the ratio of the maximum amplitude of this reflex response (Hmax) over the maximum amplitude of the direct motor response (Mmax) measures the excitable fraction of the spinal cord motoneuron pool participating in the myotatic reflex.3-7 An increase in the Hmax/Mmax ratio greater than 0.5 indicates that more than one half of the motoneuron pool is excited by stimulation of afferents derived from this muscle. It is considered to accurately reflect excitability of the motoneuron pool of the muscle recorded. This quantitative approach is one of the methods used to assess spasticity, which is a complex syndrom involving spinal reflex and peripheral changes within the muscles themselves. 8-10Spastic equinus foot is very frequent in hemiplegic patients. In the absence of effective medical treatment (including botulinum toxin or alcohol injection), this deformity can be treated by selective tibia...

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confidence: 99%