Controlled nerve ablation with direct current: parameters and mechanisms.

Spastic hypertonus (muscle over-activity) often develops after spinal cord injury or stroke. Chemodenervating agents such as Botulinum toxin A (BtA) and phenol are often used to treat this condition. We have previously shown that the use of direct current (DC) to create controlled lesions of peripheral nerves may provide a means of reducing spastic hypertonus. Here, we explored a range of stimulation parameters that could be used clinically. Nerves were lesioned with DC in chronically implanted animals and the outcome was tracked over many months. In addition, we used DC to ablate nerves in animals with decerebrate rigidity (an animal model of spastic hypertonus) and we explored the possible mechanisms of DC nerve ablation. We found that nerve ablation with DC was effective in reducing hypertonus. Some stimulation paradigms were more likely to be clinically acceptable than others. Furthermore we showed that nerve regeneration occurs in the months following DC nerve ablation and we demonstrated that the ablation procedure is repeatable, much like BtA treatment. Regarding mechanism, our results did not support the hypothesis that DC caused nerve damage by overactivating sodium channels. Rather, the mechanism of damage seems to be related to changes in pH.

Endoscopic laser thyroarytenoid myoneurectomy in patients with adductor spasmodic dysphonia: a pilot study on long-term outcome on voice quality.

OBJECTIVES: Adductor spasmodic dysphonia (ADSD) is a focal laryngeal dystonia, which compromises greatly the quality of life of the patients involved. It is a severe vocal disorder characterized by spasms of laryngeal muscles during speech, producing phonatory breaks, forced, strained and strangled voice. Its symptoms result from involuntary and intermittent contractions of thyroarytenoid muscle during speech, which causes vocal fold to strain, pressing each vocal fold against the other and increasing glottic resistance. Botulinum toxin injection remains the gold-standard treatment. However, as injections should be repeated periodically leading to voice quality instability, a more definitive procedure would be desirable. In this pilot study we report the long-term vocal quality results of endoscopic laser thyroarytenoid myoneurectomy. STUDY DESIGN: Prospective study. METHODS: Surgery was performed in 15 patients (11 females and four males), aged between 29 and 73 years, diagnosed with ADSD. Voice Handicap Index (VHI) was obtained before and after surgery (median 31 months postoperatively). RESULTS: A significant improvement in VHI was observed after surgery, as compared with baseline values (P=0.001). The median and interquartile range for preoperative VHI was 99 and 13, respectively and 24 and 42, for postoperative VHI. Subjective improvement of voice as assessed by the patients showed median improvement of 80%. CONCLUSIONS: Because long-term follow-up showed significant improvement of voice quality, this innovative surgical technique seems a satisfactory alternative treatment of ADSD patients who seek a definite improvement of their condition.

Combining ultrasonography and electromyography for botulinum chemodenervation treatment of thoracic outlet syndrome: comparison with fluoroscopy and electromyography guidance.

BACKGROUND: Botulinum chemodenervation has been increasingly used for treating conditions characterized by muscular pain and dystonia. Complication rates commonly exceed 10 percent in published accounts due to an inadvertent spread of toxin. Various techniques of precision targeting have been described to minimize undesirable toxin effects. The present study reports on a clinical experience combining ultrasonography and electromyography in order to demonstrate how favorably this approach compares to previously described techniques in terms of minimizing complications while maintaining efficacy. DESIGN: Retrospective case series METHODS: The present study is a retrospective clinical analysis of patients treated with botulinum toxin using 2 different combined targeting techniques; one using ultrasonography and electromyography and the other using fluoroscopy and electromyography. RESULTS: Combined ultrasonography and electromyography was used in 77 of 245 procedures; in 168 procedures, fluoroscopy and electromyography was used. There were no complications with ultrasonography guided procedures; the complication rate for combined fluoroscopy and electromyography was 1.8 percent (3/168; Fisher exact p = 0.3206). For combined ultrasonography and electromyography, after 70 out of 77 procedures (91%) there was a good outcome compared to 136 out of 168 (81%) after procedures utilizing a combination of fluoroscopy and electromyography (Fisher exact p= 0.331). CONCLUSIONS: There was no significant difference in complication rate or successful outcomes comparing the 2 forms of imaging guidance when targeting muscles for botulinum injection. Since outcomes are comparable, other factors such as cost and radiation exposure may be considered in choosing which imaging modality to use.

Selective peripheral denervation for the treatment of intractable spasmodic torticollis: experience with 168 patients at the Mayo Clinic.

OBJECT: Selective peripheral denervation is currently the primary surgical treatment for intractable cervical dystonia. The authors assessed preoperative factors to determine which, if any, correlated with outcomes in patients with torticollis who had undergone this procedure. METHODS: The records of 168 consecutive patients who had undergone selective peripheral denervation for cervical dystonia between 1988 and 1996 at the Mayo Clinic were reviewed. There were 89 women (53%) and 79 men (47%) with a mean age of 53.4 years. Selection of muscles for denervation was based on the patient's clinical presentation and electromyography mapping results. The most common torticollis vectors were rotational in 141 patients (84%) and laterocollis in 59 (35%). Seventy patients (42%) presented with combined vectors. The technique used to remedy both conditions involved denervation of the ipsilateral posterior cervical paraspinal and splenius capitis muscles. Denervation of the sternocleidomastoid muscle was performed on the contralateral side for rotational torticollis and on the ipsilateral side for laterocollis. A rigorous physical therapy program followed surgery. At the 3-month postoperative evaluation, 125 patients (77%) of the 162 who were available for follow up had moderate to excellent improvement in their head position, and pain was moderately to markedly improved in 131 patients (81%). The long-term follow up lasted a mean of 3.4 years and was undertaken in 130 patients. The original level of moderate to excellent improvement in head position and pain was retained in at least 71 patients (70%). Outcome was not predicted by preoperative head position, severity of abnormal posture of head, symptom duration, presence of tremor or phasic dystonic movements, or failure to respond to botulinum toxin treatment. Five patients recovered from postoperative complications including one myocardial infarction, one pulmonary embolism, and three respiratory failures. Three patients suffered from persistent C-2 distribution dysesthesias and three from slight shoulder weakness; one had a wound infection, and one died of respiratory arrest. CONCLUSIONS: Selective peripheral denervation is an effective method of achieving lasting improvement of dystonia in most patients with intractable torticollis.

[Electrophysiological investigation s in diagnosis and evaluation of ALS progress]. / Badania elektrofizjologiczne w rozpoznawaniu i ocenie zaawansowania SLA.

In diagnostics of ALS the electrophysiologic investigation should be able to evaluate two fundamental processes: the primary process of the loss of some motoneuros--denervation, and secondary process of reinnervation. The most important diagnostic methods include the quantitative electromyography (EMG) evaluating several parameters of the motor unit potential (MUP) and of the maximal effort pattern. The earliest features are the signs of spontaneous activity (denervation) and the elevation of MUP amplitude and area (reinnervation). Finding of spontaneous activity in the tongue muscles as well as in the paraspinal muscles is of great diagnostic value. SFEMG may early detect increased density of muscle fibres (FD) and jitter elongation as signs of recent reinnervation. Electroneurography is critical in differentiation against the multifocal motor neuropathy with conduction block and other polyneuropathies. The aim of the electrophysiological investigations is also the evaluation of the intensity of lesion in the muscle investigated and, indirectly, the evaluation of the progress of the disease in serial studies. It might play a great role in prognosing and in monitoring of therapeutical trials. The abnormalities in the maximal effort pattern presenting as decrease of recording density and amplitude as well as of bioelectric activity indicate in the quantitative EMG a high degree of lesion. Those signs are accompanied by altered MUP parameters: decrease of MUP amplitude and area as compared with the former stages of reinnervation. Those signs express decompensation and denervation predominating over reinnervation. In SFEMG they present as FD decrease and in Macro-EMG as decrease of amplitude as compared to the reinnervation period. Serial investigations of amplitude of the potential resulting from supermaximal stimulation (CMAP), quantitative evaluation of the maximal voluntary isometric contraction (MVIC) and the assessment of the number of motor units (MUNE) are further valuable methods in monitoring of ALS progress.