重症肌无力的膈神经和肋间神经重复电刺激

目的　探讨重症肌无力 (MG)患者膈神经重复电刺激 (PRNS)和肋间神经重复电刺激(IRNS)的特点和临床应用。方法　检测 113例MG患者PRNS、IRNS、肢体及颅神经重复电刺激 (RNS)和临床症状评分 ,并同时检测用力肺活量 (FVC)。结果　FVC取决于PRNS、IRNS及面神经RNS ;I型和Ⅱ型患者存在临床下呼吸功能障碍 ,Ⅱb型与Ⅲ型和Ⅳ型相比 ,虽PRNS波幅递减程度不同 ,但阳性率差异无显著性 ;PRNS和IRNS阳性率高于FVC和呼吸困难症状阳性率 ;PRNS敏感性高于IRNS。结论PRNS和IRNS是直接反映MG患者呼吸功能受累的神经电生理指标 ,有助于准确评估病情及进行临床分类 ;建议对Ⅱ型患者常规行PRNS和IRNS检查。     

Phrenic nerve stimulation with the quadripolar left ventricular lead not overcome by 'electronic repositioning'

Phrenic nerve stimulation (PNS) is a frequent occurrence in patients implanted with a cardiac resynchronization therapy (CRT) device. The quadripolar left ventricular offers 10 pacing configurations which can overcome PNS in most cases. We report a rare case of significant PNS following upgrade to a CRT which was present with all 10 pacing configurations one day following implantation which required lead repositioning.     

Phrenic nerve stimulation in cardiac resynchronization therapy

In cardiac resynchronization therapy (CRT), the electrical impulse delivered by the left ventricular (LV) lead may incidentally cause phrenic nerve stimulation (PNS). The purpose of this state-of-the-art review is to describe the frequency, risk factors, and clinical consequences of PNS and to present the most recent options to successfully manage PNS. PNS occurs in 2 to 37 % of implanted patients and is not always detected in the supine position during implantation. Lateral and posterior veins are at higher risk of PNS than anterior veins, and apical positions are at higher risk of PNS than basal positions. The management of PNS discovered during implantation may include mapping the course of the target vein in order to find a PNS-free site, targeting another vein if available, and pacing with alternative configurations before changing the lead location. Non-invasive options for management of post-operative PNS depend on the difference between PNS and LV stimulation thresholds and include reducing the LV pacing output, automatic determination of LV stimulation threshold and minimal output delivery by the device, increasing the pulse duration, and electronic repositioning. New quadripolar leads allow to pace from different cathodes, and the multiple pacing configurations available have proved superior to bipolar leads in mitigating PNS. This electronic repositioning addresses almost all of the clinically relevant PNS and should markedly reduce the need for invasive lead repositioning or CRT abandon, which is actually the last option for 2 % of patients.     

Elimination of phrenic nerve stimulation occurring during CRT

Background  

Phrenic nerve stimulation (PNS) occurs at follow-up in approximately 20% of patients with bipolar leads. The quadripolar Quartet model 1458Q (St. Jude Medical, Sylmar, CA, USA) left ventricular lead (LV) has four electrodes (one distal tip and three ring) capable of ten different pacing vectors which may allow reprogramming to eliminate PNS.     

Phrenic nerve stimulation,a rare complication of pacemaker: A case report

Rationale:The phrenic nerve stimulation (PNS) is a rare complication after pacemaker setting. We report a case report that describes this complication and how it can be resolved.Patient concerns:An 88-year-old man presented himself to the emergency geriatric unit with intermittent painless abdominal contraction due to phrenic nerve stimulation. He has a history of transcatheter aortic valve implantation with cardiac resynchronization therapy pacemaker due to persistent left bundle branch block.Diagnoses:All the usual causes for abdominal spasms were eliminated and the possibility of a link with the pacemaker was considered. The phrenic nerve stimulation is a rare complication of a pacemaker implantation. It can be clinically nonrelevant but challenging to diagnose for those not familiar with cardiac devices technology.Interventions:Initial setting was an axis of stimulation between distal left ventricular (LV) and right ventricular. It was changed to LV and D1-M2.Outcomes:This noninvasive procedure managed to eradicate the involuntary abdominal spasms.Lessons:PNS could be challenging to diagnose for those not familiar with cardiac devices technology but easy to manage with noninvasive methods.     

Phrenic nerve stimulation in an ovine model with temporary removable pacing leads

BackgroundThe objective of this study was to assess the feasibility and safety of a novel, removable, surgically implanted, temporary neurostimulation approach involving the distal portion of the phrenic nerve.MethodsTemporary phrenic nerve pacing electrodes were implanted surgically using an ovine model (4 animals). The primary endpoint was the ability to successfully match the animal’s minute-ventilation upon implantation of both phrenic nerve pacers on day 1. Secondary endpoints were successful phrenic neurostimulation by both electrodes 15 and 30 days after initial implantation. We also assessed safe removal of the electrodes at 15 and 30 days after implementation.ResultsIn 3 of 4 animals, electrodes were successfully implanted in both right and left phrenic nerves. On day 1, median ventilation-minute induced by neurostimulation was not significantly different from baseline ventilation-minute [4.9 L·min⁻¹ (4.4–5.5) vs. 4.4 L·min⁻¹ (4.3–5.2); P=0.4] after 15 minutes. Neurostimulation was still possible 15 and 30 days after implementation in all left side phrenic nerves. On the right side, stimulation was possible at all times in 1 animal but not in the remaining 3 animals for at least one time point, possibly due to lead displacement. Analysis of pathology after percutaneous electrode removal showed integrity of the distal portion of all phrenic nerves.ConclusionsEfficient temporary neurostimulation through the distal portion of the phrenic nerve was possible at baseline. The main complication was the displacement of electrodes on the right phrenic nerve on two occasions, which was due to the anatomy of the ovine model. It compromised diaphragm pacing on day 15 and day 30. The electrodes could be safely removed percutaneously without damage to the phrenic nerves.     

阻塞性睡眠呼吸暂停低通气综合征患者膈神经传导的变化

目的探讨膈神经传导时间(PNCT)和膈肌复合肌肉动作电位(CMAP)对阻塞性睡眠呼吸暂停低通气综合征(OSAHS)患者严重程度的评估和疗效判定的意义。方法 2005年1至7月选择健康对照组16例、单纯性鼾症组8例、OSAHS 轻中度组14例和重度组18例,使用多导食道电极结合单侧膈神经磁刺激测定 PNCT 及膈肌 CMAP 幅值。5例 OSAHS 重度患者通过有效经鼻持续气道正压通气(nCPAP)治疗2个月后复查上述指标。结果 OSAHS 重度组左、右侧 PCNT 分别为(8.9±1.2)、(7.9±1.5)ms,较健康对照组的(6.5±0.7)、(6.0±0.5)ms、单纯性鼾症组的(6.5±1.2)、(6.0±0.8)ms 及 OSAHS 轻中度组的(7.3±1.0)、(6.3±0.7)ms 均显著延长;双侧 CMAP 幅值OSAHS 轻中度组分别为(1.4±0.4)、(1.4±0.3)mV,OSAHS 重度组分别为(0.9±0.4)、(1.1±0.6)mV,较健康对照组的(2.3±0.9)、(2.1±0.9)mV 和单纯性鼾症组的(1.9±0.5)、(2.1±0.7)mV 均明显降低,OSAHS 重度组双侧 CMAP 较轻中度组显著降低。所有受试者双侧 PNCT 和 CMAP 与低氧指数、睡眠呼吸暂停低通气指数均有显著相关性。有效 nCPAP 治疗2个月后,双侧 PNCT 较治疗前均显著缩短,左侧分别为(8.6±0.6)ms、(7.4±0.5)ms,右侧分别为(7.8±0.6)ms、(6.5±0.5)ms。结论由多导食管电极和单侧膈神经刺激检测的 PNCT 和 CMAP 可能对评价 OSAHS 患者的严重程度和疗效判定有一定价值。     

Phrenic nerve function in type 1 diabetic patients with diaphragm weakness and peripheral neuropathy.

Phrenic nerve latency was studied in 14 male type 1 diabetic patients with impaired diaphragm function and in 14 healthy control subjects. The diabetics showed significantly decreased values regarding inspiratory vital capacity and forced volume in 1 s compared with the control subjects. All other lung function parameters were similar in both groups. Although motor and sensory nerve conduction studies provided evidence for peripheral neuropathy in all patients, phrenic nerve latencies turned out to be normal. These results rule out a neuropathic disorder of the phrenic nerve. Thus, impaired diaphragm function in type 1 diabetic patients is not caused by phrenic neuropathy.     

Phrenic nerve injury in infants and children undergoing cardiac surgery

Fifty infants and 50 children less than 15 years undergoing palliative or corrective cardiac surgery in the Brompton Hospital between March and October 1988 had direct percutaneous stimulation of the phrenic nerve before and after operation. Ten patients, six under 1 year of age and four over, developed unilateral phrenic nerve injury. In those aged less than 1 year recovery after operation was prolonged because their diaphragmatic palsy made it difficult to wean them from the ventilator. Older children had symptoms but their rate of recovery did not seem to be affected by the phrenic nerve injury. Phrenic nerve damage was no more frequent after a lateral thoracotomy than after a median sternotomy. There was no significant association with the type of operation performed, the experience of the surgeon, the use of bypass or topical ice, the duration of bypass, circulatory arrest or aortic cross clamping, or the age of the patient at the time of operation. In patients who had cardiopulmonary bypass the risk of injury was significantly higher in those who had undergone previous operation. The 10% frequency of phrenic nerve injury determined in this prospective study was higher than that seen in earlier retrospective reports. Direct percutaneous stimulation of the phrenic nerve can be used at the bedside in infants and children to facilitate early and accurate diagnosis of phrenic nerve palsy, and the results may influence early management.     

Phrenic nerve responses to hypoxia and CO2 in decerebrate dogs

Phrenic responses to isocapnic hypoxia and hypercapnia were studied using paralyzed vagotomized dogs (either decerebrate or chloralose-anesthetized). The hypoxia-induced increase in phrenic minute activity (PMA) was significantly greater in anesthetized dogs when compared with the response observed in decerebrate dogs. Phrenic responses to hypercapnia were also significantly different in the two groups of dogs. Increases in phrenic amplitude (AMP) and frequency (FREQ) were observed in anesthetized dogs, whereas decerebrate dogs responded to CO2 without a change in FREQ. Spontaneously breathing dogs (either decerebrate or anesthetized) were used for studying the effects of vagotomy on the integrated phrenic neurogram. Changes in phrenic pattern in response to vagotomy were qualitatively similar in anesthetized and decerebrate dogs. However, in decerebrate dogs, AMP was disproportionately increased relative to the decrease in FREQ such that PMA increased following vagal transection. Conversely, in anesthetized dogs, the increase in AMP and decrease in FREQ in response to vagotomy were proportional; PMA remained unchanged. These results suggest that mesencephalic decerebration disrupts neuronal circuits which participate in the chemical control of breathing. In addition, suprapontine structures may be involved in coupling FREQ and AMP (tidal volume) so that PMA (ventilation) is stabilized. Finally, these studies provide evidence for a vagally-independent frequency controller in dogs which is sensitive to hypoxia and hypercapnia, but appears to be highly dependent upon suprapontine structures.     

Phrenic nerve injury in infants and children undergoing cardiac surgery.

Fifty infants and 50 children less than 15 years undergoing palliative or corrective cardiac surgery in the Brompton Hospital between March and October 1988 had direct percutaneous stimulation of the phrenic nerve before and after operation. Ten patients, six under 1 year of age and four over, developed unilateral phrenic nerve injury. In those aged less than 1 year recovery after operation was prolonged because their diaphragmatic palsy made it difficult to wean them from the ventilator. Older children had symptoms but their rate of recovery did not seem to be affected by the phrenic nerve injury. Phrenic nerve damage was no more frequent after a lateral thoracotomy than after a median sternotomy. There was no significant association with the type of operation performed, the experience of the surgeon, the use of bypass or topical ice, the duration of bypass, circulatory arrest or aortic cross clamping, or the age of the patient at the time of operation. In patients who had cardiopulmonary bypass the risk of injury was significantly higher in those who had undergone previous operation. The 10% frequency of phrenic nerve injury determined in this prospective study was higher than that seen in earlier retrospective reports. Direct percutaneous stimulation of the phrenic nerve can be used at the bedside in infants and children to facilitate early and accurate diagnosis of phrenic nerve palsy, and the results may influence early management.     

Phrenic nerve palsy in a patient of Churg Strauss syndrome and mononeuritis multiplex

Neurological manifestations like mononeuritis multiplex are seen commonly in patients with Churg Strauss syndrome. Cranial nerve involvement and central nervous system involvement are also reported, although infrequently. Phrenic nerve involvement has not been reported so far. We report a patient with Churg Strauss syndrome who presented with mononeuritis multiplex and developed left-sided phrenic nerve palsy subsequently.     

Transcutaneous nerve stimulation in patients with coronary arterial disease: haemodynamic and biochemical effects

Low-frequency transcutaneous nerve stimulation (TNS) is known to produce widespread and prolonged vasodilation in skin and muscles. In the present study the effects of low-frequency TNS on coronary and systemic haemodynamics, myocardial blood flow, myocardial oxygen consumption, myocardial free fatty acid and lactate uptake were measured at rest in 16 normotensive patients, with coronary heart disease, undergoing diagnostic cardiac catheterization. In addition, vasoactive intestinal polypeptides (VIP) and noradrenaline were measured in the coronary sinus and the aorta. The study was randomized and double-blind, with half of the patients serving as placebo controls. A stimulation period of 20 min caused a significant lowering of mean femoral arterial pressure and systemic vascular resistance measured at 15 and 30 min after the start of TNS (P less than 0.01). There was no significant change in the other parameters mentioned. The hypotonic effect is considered to be due to increased peripheral microcirculation resulting from sympatho-inhibition.     

Effect of sacral nerve stimulation in patients with fecal and urinary incontinence

PURPOSE: Preliminary studies have shown improvement in fecal incontinence in several patients who received temporary or permanent stimulation. The purpose of this study was to report our experience in sacral nerve stimulation in the treatment of fecal incontinence and to target patients who would benefit most from stimulation. METHODS: Patients with fecal incontinence were studied clinically and manometrically before, during, and after temporary nerve stimulation. If temporary nerve stimulation was clinically successful, the patient was implanted and followed up for six months. RESULTS: Nine patients (6 female) with a mean age of 50.7 ± 12.3 years underwent temporary nerve stimulation. Temporary nerve stimulation was successful in eight patients, six of whom were implanted. Of the patients who could be evaluated, three of five had improved at the six-month follow-up visit, particularly in relation to the number of urgency episodes and delay in postponing defecation. All implanted patients had urinary symptoms. Urinary urgency was also improved by stimulation. During temporary nerve stimulation, the maximal squeeze pressure amplitude increased. After implantation, only the duration of maximal squeeze pressure seemed to improve. CONCLUSION: Sacral nerve stimulation can be used in the management of fecal incontinence, particularly in cases of urge fecal incontinence associated with urinary urgency. This study seems to confirm the effect of sacral nerve stimulation on striated sphincter function.Presented in part at the 7th United European Gastroenterology Week, Rome, Italy, November 13 to 17, 1999; the Brain-Gut 2000 Symposium, Toulouse, France, July 2 to 5, 2000; and the Second International Conference on the Pelvic Floor, Oxford, England, September 9 to 12, 2000.