Anaya Niño M.C.1, Herrera Villabona E.2
1Santander Industrial University, Santander, Bucaramanga, Colombia, 2Universidad Industrial de Santander, Santander, Bucaramanga, Colombia
Background: Cryotherapy is a therapeutic method frequently used in clinical situations to reduce spasticity. However, its effect on the reflex excitability and the activation pattern of spastic muscle and their antagonists is unclear.
Purpose: To assess the immediate and delayed effect of the application of ice pack(IP) on the reflex excitability of the soleus and activation pattern of the plantar flexor spastic muscles and their antagonists in people post-stroke.
Methods: A randomized experimental study of repeated measurements with two intervention groups was performed: Ice pack group (IPG, n=10) and control group (CG, n=5). Measurements times were before(T0), inmediatly after(T1) and 30 minutes post cooling(T2). The H-reflex measurements were made using a Nicolet Compass Meridian System. Latency (ms), duration (ms), amplitude (mV) of M and H waves and the Hmax/Mmax amplitude ratio were recorded. Electromiographic activity was assessed by a submaximal isometric voluntary contraction (SIVC in dorsal flexion and plantar flexion), Root Mean Square (RMS) amplitude and Median Frequency (MF, Hz) using a Surface electromyography Biometrics. Comparisons between T0, T1 and T2 for each group were performed using paired t-test or Wilcoxon sign-rank test, after verification of the distribution of variables An analysis of covariance (ANCOVA) was performed for each of the post-intervention times, adjusting by the initial measurement and intervention group. The Stata 12.0 software was used with a significance level of 0.05.
Results: Fifteen subjects with spastic hemiparesis post-stroke were screened, age 60.7±10.7 years, injury duration Median=36 (IQR=17-49) months. There were no significant differences in baseline characteristics by groups. Cryotherapy induces to a significant increase in the H wave latency between T0-T1 and T0-T2 (2.0±0.3 and 1.4±0.8ms, p 0.001, respectively) and M wave (1.4±1.4 and 0.9±1.3ms, p 0.05). Cryotherapy increase the duration of the M wave (3.5±1.1 and 1.4±1.6ms, p 0.001) and H wave (2.7±2.1 y 1.2±1.2ms, p 0.001). In the IPG the MF of the tibialis anterior increased between T0-T2 (8.2±9.6, p 0.05) and soleus decreased between T0-T1 (15.1±13.6, p 0.001). During the SIVC in plantar flexion there was an increase in both records of the RMS amplitude (p 0.05) and a decreased in the soleus MF, immediately and 30 minutes after cooling (20.9±14.0 and 8.8±8.6Hz, respectively). ANCOVA showed H-reflex latency (p=0.000), duration wave H (p=0.008) and MF of SIVC in dorsal flexion (p=0.01) and plantar flexion (p= 0.006) have a significant difference between the two groups, to adjust the measurement immediately after the intervention with the initial measurement. Thirty minutes after removal IP, only the duration of the H wave (p=0.01) and soleus MF during the SIVC in plantar flexion (p=0.03) showed a significant difference between the groups.
Conclusion(s): The findings suggest that cooling can have therapeutic effects on spasticity, delayed muscle response evoked by direct and reflects electrical stimulation. Consequently, improving the recruitment pattern of motor units both soleus and its antagonist, during SIVC in dorsal and plantar flexion.
Implications: The IP is a useful modality in the management of spasticity post-stroke and could be used in conjunction with other therapeutic strategies to improve the functional performance of hemiparetic persons.
Funding acknowledgements: Work funded by the University Industrial of Santander, Colombia.
Topic: Neurology: stroke
Ethics approval: This research was approved by the Committee on Scientific Research of the Industrial University of Santander CIENCI (Registration D13-16096), Colombia.
All authors, affiliations and abstracts have been published as submitted.
