The risk of iatrogenic damage is very high in surgical interventions in or around the brainstem. However, surgical techniques and intraoperative neuromonitoring (ION) have evolved sufficiently to increase the likelihood of successful functional outcomes in many patients. We present a critical review of the methodologies available for intraoperative monitoring and mapping of the brainstem. There are three main groups of techniques that can be used to assess the functional integrity of the brainstem: 1) mapping, which provides rapid anatomical identification of neural structures using electrical stimulation with a hand-held probe, 2) monitoring, which provides real-time information about the functional integrity of the nervous tissue, and 3) techniques involving the examination of brainstem reflexes in the operating room, which allows for the evaluation of the reflex responses that are known to be crucial for most brainstem functions. These include the blink reflex, which is already in use, and other brainstem reflexes that are being explored, such as the masseter H-reflex. This is still under development but is likely to have important functional consequences. Today an abundant armory of ION methods is available for the monitoring and mapping of the functional integrity of the brainstem during surgery. ION methods are essential in surgery either in or around the brainstem; they facilitate the removal of lesions and contribute to notable improvements in the functional outcomes of patients.
Blinking ; Brain Stem* ; Electric Stimulation ; H-Reflex ; Humans ; Monitoring, Intraoperative* ; Operating Rooms ; Reflex

The risk of iatrogenic damage is very high in surgical interventions in or around the brainstem. However, surgical techniques and intraoperative neuromonitoring (ION) have evolved sufficiently to increase the likelihood of successful functional outcomes in many patients. We present a critical review of the methodologies available for intraoperative monitoring and mapping of the brainstem. There are three main groups of techniques that can be used to assess the functional integrity of the brainstem: 1) mapping, which provides rapid anatomical identification of neural structures using electrical stimulation with a hand-held probe, 2) monitoring, which provides real-time information about the functional integrity of the nervous tissue, and 3) techniques involving the examination of brainstem reflexes in the operating room, which allows for the evaluation of the reflex responses that are known to be crucial for most brainstem functions. These include the blink reflex, which is already in use, and other brainstem reflexes that are being explored, such as the masseter H-reflex. This is still under development but is likely to have important functional consequences. Today an abundant armory of ION methods is available for the monitoring and mapping of the functional integrity of the brainstem during surgery. ION methods are essential in surgery either in or around the brainstem; they facilitate the removal of lesions and contribute to notable improvements in the functional outcomes of patients.
Blinking ; Brain Stem* ; Electric Stimulation ; H-Reflex ; Humans ; Monitoring, Intraoperative* ; Operating Rooms ; Reflex

PURPOSE: A limited number of studies have examined the link between F-wave abnormalities and clinical presentation in pediatric Guillain-Barré syndrome (GBS). Therefore, this study examined the importance of F-wave abnormalities as a prognostic factor in pediatric GBS patients. METHODS: The records and electrodiagnostic studies (EDS) of 70 GBS patients were retrospectively evaluated, and divided into 2 groups according to the results of EDS. Group A (n=33) presented with F-wave abnormalities, and group B (n=26) exhibited normal findings. We compared laboratory reports, clinical features, response to treatment, and prognosis between the 2 groups. RESULTS: Motor weakness was the most frequently observed symptom for either group. Clinically, the incidence of fever and upper respiratory symptoms differed between the 2 groups, while the prevalence of abnormal deep tendon reflex (DTR) was significantly higher in group A than B (P<0.05). Patients diagnosed with GBS had received intravenous immunoglobulin treatment: 94% in group A and 58% in group B. Furthermore, significantly greater numbers of patients in group A showed H-reflex abnormalities and poor prognosis compared with group B (P<0.05). CONCLUSION: This study demonstrated that F-waves are a clinically important prognostic factor in GBS. F-wave abnormalities were associated with abnormal DTR and poor prognosis in patients. Limited studies have examined the link between F-wave abnormalities and clinical results; therefore, further randomized controlled studies are needed to confirm the clinical characteristics and efficacy of treatments.
Child* ; Fever ; Guillain-Barre Syndrome* ; H-Reflex ; Humans ; Immunoglobulins ; Incidence ; Prevalence ; Prognosis ; Reflex, Abnormal ; Retrospective Studies

OBJECTIVETo study the role of proximal nerve stimulation at Erb point in the early diagnosis of Guillain-Barré syndrome (GBS) in children.

METHODSThirty-two children who were diagnosed with GBS between October 2013 and December 2014 received neurophysiological examination. Thirty healthy children were used as controls. Compound muscle action potentials and distal motor latency of the median and ulnar nerves were determined and analyzed after nerve stimulation at the wrist, elbow, and Erb point in the two groups. Moreover, F-wave latency of the median nerve and H-reflex latency of the tibial nerve were measured and analyzed in the two groups.

RESULTSThe F-wave and H-reflex latencies were significantly longer in the patient group than in the control group (P<0.05). In thirty-two patients, the numbers of patients with abnormal amplitude, abnormal latency, and conduction block at Erb's point were 24 (75%), 22 (69%), and 20 (62%), respectively. The patient group had significantly lower amplitudes but significantly longer latencies of the ulnar and median nerves at Erb point than the control group (P<0.05). There were no significant differences in the amplitudes and latencies at the wrist and elbow between the two groups (P>0.05).

CONCLUSIONSThe nerve stimulation at Erb point holds promise as a routine examination for the early diagnosis of GBS.

Adolescent ; Child ; Early Diagnosis ; Electrodiagnosis ; methods ; Female ; Guillain-Barre Syndrome ; diagnosis ; physiopathology ; H-Reflex ; Humans ; Male ; Neural Conduction ; physiology ; Reaction Time

OBJECTIVE: To investigate the electrophysiological effects of focal vibration on the tendon and muscle belly in healthy people. METHODS: The miniaturized focal vibrator consisted of an unbalanced mass rotating offset and wireless controller. The parameters of vibratory stimulation were adjusted on a flat rigid surface as 65 microm at 70 Hz. Two consecutive tests on the different vibration sites were conducted in 10 healthy volunteers (test 1, the Achilles tendon; test 2, the muscle belly on the medial head of the gastrocnemius). The Hoffman (H)-reflex was measured 7 times during each test. The minimal H-reflex latency, maximal amplitude of H-reflex (Hmax), and maximal amplitude of the M-response (Mmax) were acquired. The ratio of Hmax and Mmax (HMR) and the vibratory inhibition index (VII: the ratio of the Hmax after vibration and Hmax before vibration) were calculated. The changes in parameters according to the time and site of stimulation were analyzed using the generalized estimating equation methods. RESULTS: All subjects completed the two tests without serious adverse effects. The minimal H-reflex latency did not show significant changes over time (Wald test: chi2=11.62, p=0.07), and between the two sites (chi2=0.42, p=0.52). The changes in Hmax (chi2=53.74, p<0.01), HMR (chi2=20.49, p<0.01), and VII (chi2=13.16, p=0.02) were significant over time with the adjustment of sites. These parameters were reduced at all time points compared to the baseline, but the decrements reverted instantly after the cessation of stimulation. When adjusted over time, a 1.99-mV decrease in the Hmax (chi2=4.02, p=0.04) and a 9.02% decrease in the VII (chi2=4.54, p=0.03) were observed when the muscle belly was vibrated compared to the tendon. CONCLUSION: The differential electrophysiological effects of focal vibration were verified. The muscle belly may be the more effective site for reducing the H-reflex compared to the tendon. This study provides the neurophysiological basis for a selective and safe rehabilitation program for spasticity management with focal vibration.
Achilles Tendon ; Electrophysiology ; H-Reflex ; Head ; Healthy Volunteers ; Muscle Spasticity ; Reflex, Monosynaptic ; Rehabilitation ; Tendons* ; Vibration

The aim of the present study was to establish a minimally invasive H reflex model in mice for the benefit of the research of clinical spinal cord injury and related diseases. Minimally invasive surgery was performed in hind limb of Kunming mouse under light anesthesia. The skin was incised at the point of one-third of the distance from greater trochanter to the base of the cauda. A pair of fine copper conductors were inserted into the shallow muscle using a syringe needle. After the needles were withdrawed, the retained conductors were ligated and fixed with the tissues surrounding the sciatic nerve as the first pair of stimulating electrodes. Another pair of conductors were inserted and fixed in medial malleolus close to the tibial nerve as the second stimulating electrodes. Copper conductor was inserted passing the skin above the proximal end of the metatarsal and fixed as the recording electrode. The reference electrode was placed at the walking pad in the base of the big toe using the same method. Electromyography (EMG) was used to record M and H waves in planta pedis muscles. The stimulus was a square wave with a width of 0.2 ms and frequency of 0.3 Hz. The latency time of the M and H waves which were induced from the two pairs of stimulating electrodes was recorded. Nerve conduction velocity (NCV) was then calculated from the distance between the cathodes of the stimulating electrodes and the latency time difference of M or H waves. The result showed the achievement ratios of H reflex induction were 92.73% and 81.82% in sciatic and tibial nerves, respectively. The latency time of H wave was about 7~10 ms. Motor nerve conduction velocity (MNCV) obtained was (25.84 ± 4.70) m/s (n = 35), while sensory nerve conduction velocity (SNCV) was (31.45 ± 7.30) m/s (n = 35). The method established in the present paper is simple to practice, does slight harm to the animal, and can produce waveforms with little interference. With these advantages, the method can be applied for the study of the latency of H reflex, and it is suitable for the researches which demands good physical condition of experimental animal during H reflex study. This model can also be applied to the detection of SNCV and MNCV.
Animals ; Electromyography ; H-Reflex ; physiology ; Hindlimb ; innervation ; Mice ; Neural Conduction ; physiology ; Tibial Nerve ; physiology

OBJECTIVETo investigate the effects of 100 Hz sinusoidal vibration on H reflex and M wave in rat soleus muscle following immobilization.

METHODSThe immobilization of rat soleus muscle was induced as a disuse muscle model, and 100 Hz sinusoidal vibration was generated by a vibrator and applied to the immobilized soleus muscle, then the changes of H reflex and M wave in muscle were observed after 14 d.

RESULTSCompared to control, after 14 d of immobilization M(max) in soleus muscle decreased (P<0.01), stimulus threshold and S(max) increased (P<0.01); Hmax and H(max)/M(max) decreased (P<0.05, S(max) increased (P<0.05). Compared to immobilized soleus muscle, after 14 d of immobilization with 100 Hz sinusoidal vibration, the M(max) increased(P<0.01), stimulus threshold and S(Mmax) decreased (P<0.05), H(max) (P<0.01) increased and H(max)/M(max) increased (P<0.05).

CONCLUSION100 Hz sinusoidal vibration plays a significant antagonist role against the changes in H reflex and M wave in rat soleus muscle following immobilization.

Animals ; Electromyography ; Female ; H-Reflex ; physiology ; Hindlimb Suspension ; Muscle Contraction ; physiology ; Muscle Spindles ; physiology ; Muscle, Skeletal ; physiology ; Rats ; Rats, Sprague-Dawley ; Vibration

OBJECTIVE: To evaluate the spasticity and electrophysiologic effects of applying extracorporeal shock wave therapy (ESWT) to the gastrocnemius by studying F wave and H-reflex. METHOD: Ten healthy adults and 10 hemiplegic stroke patients with ankle plantarflexor spasticity received one session of ESWT on the medial head of the gastrocnemius. The modified Ashworth scale (MAS), tibial nerve conduction, F wave, and H-reflex results were measured before and immediately after the treatment. The Visual Analogue Scale (VAS) was used during ESWT to measure the side effects, such as pain. RESULTS: There were no significant effects of ESWT on the conduction velocity, distal latency and amplitude of tibial nerve conduction, minimal latency of tibial nerve F wave, latency, or H-M ratio of H-reflex in either the healthy or stroke group. However, the MAS of plantarflexor was significantly reduced from 2.67+/-1.15 to 1.22+/-1.03 (p<0.05) after applying ESWT in the stroke group. CONCLUSION: After applying ESWT on the gastrocnemius in stroke patients, the spasticity of the ankle plantarflexor was significantly improved, with no changes of F wave or H-reflex parameters. Further studies are needed to evaluate the mechanisms of the antispastic effect of ESWT.
Adult ; Animals ; Ankle ; H-Reflex ; Head ; Humans ; Muscle Spasticity ; Shock ; Stroke ; Tibial Nerve

OBJECTIVE: To investigate the electrophysiological changes after botulinum toxin type A injection in children with cerebral palsy. METHOD: Sixteen children with spastic cerebral palsy enrolled in the study. Botulinum toxin type A (Dysport(R)) was injected into gastrocnemius muscles. Electrophysiological assessments included the compound motor action potential of the tibial nerve, the sensory nerve action potential of the sural nerve, the H-reflex and the T-reflex before injection, and at 2 weeks and 4 weeks after the injection. Modified Ashworth scale was used to evaluate spasticity before, 2 weeks and 4 weeks after the injection. RESULTS: Modified Ashworth scale of the ankle decreased at 2 weeks and 4 weeks after injection. The amplitude of the H-reflex and H(max)/M(max) ratio decreased significantly at 4 weeks. The amplitude of the T-reflex decreased at 2 weeks and 4 weeks. The correlation between changes in modified Ashworth scale of the ankle and the changes in electrophysiological parameters at 4 weeks after injection were not significant. CONCLUSION: The change in T-reflex is faster than the change of H-reflex and H(max)/M(max) ratio after botulinum toxin A injection in children with cerebral palsy. Electrophysiological tests could quantify the change in spasticity after botulinum toxin injection.
Action Potentials ; Animals ; Ankle ; Botulinum Toxins ; Botulinum Toxins, Type A ; Cerebral Palsy ; Child ; H-Reflex ; Humans ; Muscle Spasticity ; Muscles ; Organic Chemicals ; Sural Nerve ; Tibial Nerve

OBJECTIVE: To evaluate the effects of high frequency repetitive transcranial magnetic stimulation (rTMS) of the affected hemisphere on the motor recovery and spasticity in chronic post-stroke hemiplegic patients. METHOD: Thirteen chronic stroke hemiplegic patients were randomized to receive real and sham rTMS. rTMS was carried out 10 times at a frequency of 10 Hz with 10 s stimulation followed by 50 s rest, totalling 1,000 stimulations to the affected primary motor cortex using an intensity of 100% of resting motor threshold of unaffected hemisphere. Median nerve H-reflex, modified Ashworth scale (MAS) at elbow and wrist, and manual function test (MFT) were measured at baseline and after 2 weeks of treatment. RESULTS: High frequency rTMS resulted in increased H-reflex latency and decreased H-reflex amplitude and H/M ratio. Also MAS decreased and MFT score increased after 2 weeks of treatment. CONCLUSION: High frequency rTMS in the affected motor cortex might facilitate motor recovery and reduce spasticity in chronic stroke patients.
Elbow ; H-Reflex ; Humans ; Median Nerve ; Motor Cortex ; Muscle Spasticity ; Salicylamides ; Stroke ; Transcranial Magnetic Stimulation ; Wrist