Optimal Interstimulus Interval For Consecutive H-Reflex Responses In Patients With Spasticity
Condition: Muscle Hypertonia; Reflex, Abnormal
MeSH terms: Muscle Spasticity; Muscle Hypertonia; Reflex, Abnormal
Study type: Interventional

Summary: 
      This study evaluates the optimal interstimulus interval for consecutive H-reflex responses in
      patients with spasticity.
    

Detailed description: 
      This study will include 15 patients with spastic stroke patients H-reflex with different
      interstimulus interval of the plegic side soleus muscle will be tested.

      Subjects lay comfortably in the supine position on an examination bed. The subject will be
      asked not to contract the lower extremity muscles during the experiment. Surface EMG (SEMG)
      will be recorded from the plegic side soleus muscle using bipolar electrodes. These
      electrodes will be placed on the soleus muscle according to the SENIAM guideline.The
      reference electrode will be placed on medial malleolus. Prior to electrode placement, the
      skin will be shaved, lightly abraded, and cleaned with alcohol wipes. Self-adhesive,
      disposable, Ag-AgCl disc electrodes with a disc radius of 10 mm (KENDALL® Arbo; Coviden;
      Massachusetts, USA) will be used. To prevent the sway of electrode cables, it will be fixed
      to the body. SEMG and stimulator data will be obtained by using a data acquisition system
      (POWERLAB® ADInstruments Co, Oxford, United Kingdom). Sampling rate will be 10 kHz.

      The recorded data will be processed and analyzed offline using LabChart7® Software Version
      V7.3.3 (PowerLab® system ADInstruments, Oxford, United Kingdom).

      A cathode (5×5 mm) will be placed at the midpoint of popliteal fossa and an anode (10×10 cm)
      will be placed immediately proximal to the patella to evoke the H-reflex for monopolar
      stimulation of the posterior tibial nerve. A monophasic electrical current will be delivered
      as square pulses with a width of 1 ms by using a stimulator (FE155 Stimulator HC
      ADInstrument, Oxford UK). Taking into consideration study of Ozyurt et al, interstimulus
      interval will be selected as 10 seconds for determining the maximum H-reflex (Hmax). Then,
      Hmax and M-response (Mmax) will be determined.

      We will be tested four different ISI (10s, 5s, 3s and 1s) for stroke patients in this study.
      The stimulus intensity for tested H-reflex will be selected as a constant stimulus strength
      that will be 50 percent of the Hmax.

      Thirty consecutive stimuli will be delivered in separate sets for each tested ISI of 10, 5, 3
      and 1s. The ISI sets will be tested in random order to negate any order effect. There will be
      a 15s of interval between sets.

      SEMG recordings will be filtered using a bandpass filter from 5 to 500 Hz. Then the
      peak-to-peak (P-P) amplitudes of H-reflex will be measured then normalized using by two
      different methods to estimate H-reflex suppression due to consecutive stimuli. In the first
      method, P-P amplitude of the first H-reflex response will be used as a control, and P-P
      amplitude of the second H-reflex response will be normalized by using the control for each
      ISI set. Thus, HPP2 / HPP1 ratio will be calculated. Similar to the previous method, the
      first H-reflex response will be used as the control in the second method. Unlike the first
      method, not only the second H-reflex response, but the remaining 29 H-responses will be
      normalized to the first H-response. P-P amplitude of the 29 normalized H-reflex responses
      will be averaged and HPP29/HPP1 ratio will be calculated.

      The peak-to-peak amplitude of the first H-reflex response will be measured then normalized to
      the Mmax (HPP1/Mmax) to compare H-reflexes between subjects and conditions.
    

Intervention name(s): H-reflex
Intervention type(s): Diagnostic Test
Intervention description(s): Electrical stimulation of Group Ia afferent of muscle spindle
Intervention model: Single Group Assignment
Intervention model description: Effects of spasticity on consecutive H-reflex response in patients with hemiplegia
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: muscle spindle; H reflex; spasticity