Intraoperative and perioperative complications with a vagus nerve stimulation device

Vagus nerve stimulation (VNS) for medically refractory seizures has been an approved therapy by the Food and Drug Administration since 1997, with additional approval as an adjunct therapy for major depression granted in 2005. Potential applications for VNS therapy in obesity, neuropsychiatric disorders, and chronic pain syndromes are under investigation. Bradyarrhythmias, including asystole, may occur during VNS device placement or as a delayed complication. A peritracheal hematoma may develop following VNS device placement, necessitating emergent management. Other respiratory complications may include vocal cord movement abnormalities with potential for aspiration. Vagus nerve stimulation results in sleep-related breathing pattern changes, with an associated increase in the number of obstructive apneas and hypopneas in both children and adults, which may impact perioperative care.     

Transcranial magnetic stimulation of primary motor cortex affects mental rotation

Neuroimaging studies have shown that motor structures are activated not only during overt motor behavior but also during tasks that require no overt motor behavior, such as motor imagery and mental rotation. We tested the hypothesis that activation of the primary motor cortex is needed for mental rotation by using single- pulse transcranial magnetic stimulation (TMS). Single-pulse TMS was delivered to the representation of the hand in left primary motor cortex while participants performed mental rotation of pictures of hands and feet. Relative to a peripheral magnetic stimulation control condition, response times (RTs) were slower when TMS was delivered at 650 ms but not at 400 ms after stimulus onset. The magnetic stimulation effect at 650 ms was larger for hands than for feet. These findings demonstrate that (i) activation of the left primary motor cortex has a causal role in the mental rotation of pictures of hands; (ii) this role is stimulus-specific because disruption of neural activity in the hand area slowed RTs for pictures of hands more than feet; and (iii) left primary motor cortex is involved relatively late in the mental rotation process.     

Cervical vagus nerve stimulation for treatment-resistant depression

Therapeutic brain stimulation through left cervical VNS now has established safety and efficacy as a long-term adjunct treatment for medication-resistant epilepsy. There is considerable evidence from both animal and human studies that the vagus nerve carries afferent signals to limbic and higher cortical brain regions, providing a rationale for its possible role in the treatment of psychiatric disorders. Open-label studies in patients with treatment-resistant depression have produced promising results, especially when response rates at longer term (1 year and 2 years) follow-up time points are considered. Short-term (10 weeks) treatment with VNS failed to demonstrate statistical superiority over sham treatment in a recently completed double-blind study, so antidepressant efficacy has not yet been established. Longer term data on VNS in depressed patients as well as further information regarding the possible dose-response relation will help to determine the place of VNS in the armament of therapeutic modalities available for major depression.     

Hardware failure in vagus nerve stimulation therapy

Summary A 20 year old male patient who had been successfully treated for epilepsy with vagus nerve stimulation (VNS) for 7 years (50% seizure frequency reduction), had experienced multiple episodes of severe hoarseness, throat pain and impaired breathing during physical exercise. As malfunctioning of the pulse generator was suspected, it was decided to replace the device. During surgery, the pulse generator was found to have broken in two, due to an unstable connection between the battery subunit and the connector subunit. With a new pulse generator seizure frequency reduction was restored. No side effects occurred. Correspondence: Kim Rijkers, M.D., Department of Neurosurgery, Maastricht University Hospital, PO BOX 5800, 6202 AZ Maastricht, The Netherlands.     

Perioperative anaesthetic management of an epileptic patient treated with a vagus nerve stimulation

The vagal nerve stimulation is approved for medically refractory epilepsy and major depression. We report the perioperative management of an epileptic patient with this indwelling device. This observation summarizes the physiologic implications and the specific anaesthetic considerations for procedures with this pre-existing device.     

无创迷走神经刺激的临床应用进展

迷走神经活性的调节影响大脑和身体之间的信息传递过程及生理状态。无创迷走神经刺激（nVNS）通过刺激耳迷走神经或颈部迷走神经对多个器官和系统产生保护作用,远程调节机体功能。近年来nVNS在预防及治疗神经系统疾病、自身免疫相关性疾病及心血管系统疾病中取得重大进展。本文对nVNS及相关技术的应用研究进展进行综述,为进一步探索nVNS在围术期的应用提供参考。     

Validation and the future of stimulation therapy of the primary motor cortex

The use of electrical motor cortex stimulation (EMCS) for post-stroke pain was established in Japan and has spread globally. EMCS has been used for the treatment of neuropathic pain, Parkinson's syndrome, and recovery of motor paresis. Since 2000, repetitive transcranial magnetic stimulation (rTMS) has been developed for the treatment of various neurological disorders. rTMS is a non-invasive method with almost no adverse effects. In the USA, rTMS of the left dorsolateral prefrontal cortex was approved for the treatment of major depression in 2008. rTMS of the primary motor cortex (M1) has been studied worldwide for the treatment of neuropathic pain, Parkinson's disease, motor paresis after stroke, and other neurological problems. New methods and devices for rTMS therapy are under development, and rTMS of the M1 is likely to be established as an effective therapy for some neurological disorders. The present review discusses EMCS and rTMS of the M1 concisely.     

迷走神经刺激影响器官功能的研究进展

迷走神经是副交感神经系统的主要承担者,可以调控炎症反应及器官功能。围术期手术和麻醉等刺激可导致机体迷走神经张力相对降低,导致围术期循环、呼吸、消化、神经等系统相关并发症的发生率升高。本文就迷走神经张力降低对围术期多器官功能的影响及迷走神经刺激在器官功能中的应用做一综述,为减少围术期各种并发症的发生提供新思路。     

Outcome of long-term vagus nerve stimulation for intractable epilepsy

The outcome of long-term vagus nerve stimulation (VNS) was evaluated in 13 Japanese patients with intractable epilepsy, all followed up for more than 4 years (48-91 months, median 56 months). VNS achieved a long-lasting and cumulative seizure-control effect in nine of 13 patients. The mean reduction of seizure frequency in the 1st to 4th year was 28%, 47%, 54%, and 63%, respectively. The percentage of patients with >60% seizure reduction in the 1st to 4th year was 15%, 46%, 54%, and 69%, respectively. One patient did not respond to the treatment at all. No patient became completely free from seizure or free from medication, but the number and/or dosage of antiepileptic drugs was reduced in five patients. Ten patients underwent exchange of the generator and continued treatment, and two patients underwent removal of the generator because of the unsatisfactory result. VNS controlled more disabling seizures earlier and more efficiently than less disabling seizures in seven patients. The cumulative reduction of seizures was partly associated with changes in the device setting toward increased stimulation. These effects were similar in patients with or without previous resective surgery. Long-term VNS therapy achieved a favorable outcome in a significant proportion of patients with intractable epilepsy.     

Management of vagus nerve stimulation therapy in the peri-operative period

Vagus nerve stimulation is a well-established treatment option for patients with drug-resistant epilepsy and has an expanding range of other clinical indications. Side effects of vagus nerve stimulation therapy include: cough; voice changes; vocal cord adduction; rarely, obstructive sleep apnoea; and arrhythmia. Patients with implanted vagus nerve stimulation devices may present for unrelated surgery and critical care to clinicians who are unfamiliar with their function and safe management. These guidelines have been formulated by multidisciplinary consensus based on case reports, case series and expert opinion to support clinicians in the management of patients with these devices. The aim is to provide specific guidance on the management of vagus nerve stimulation devices in the following scenarios: the peri-operative period; peripartum period; during critical illness; and in the MRI suite. Patients should be aware of the importance of carrying their personal vagus nerve stimulation device magnet with them at all times to facilitate urgent device deactivation if necessary. We advise that it is generally safer to formally deactivate vagus nerve stimulation devices before general and spinal anaesthesia. During periods of critical illness associated with haemodynamic instability, we also advise cessation of vagus nerve stimulation and early consultation with neurology services.     

Effect of vagus nerve stimulation on thermal injury in rats

Objective

To investigate the effects of vagus nerve stimulation on haemodynamics, pulmonary histopathology, arterial blood gas and pro-inflammatory responses to thermal injury.

Interventions

Forty-eight male Sprague–Dawley (SD) rats were randomly divided into six equal groups: normal control (NC) group; thermal injury (TEM) group subjected to 40% total body surface area (%TBSA) third-degree thermal injury; vagotomy (VGX) group subjected to bilateral cervical vagotomy after thermal injury; electrical stimulation (STM) group subjected to bilateral cervical vagotomy plus the left vagus nerve trunk electrical stimulation (5 V, 2 ms and 1 Hz) after thermal injury; the antagonist of muscarinic acetylcholine receptor (MRA) group administrated with atropine (0.1 mg kg⁻¹) before electrical stimulation and the antagonist of nicotinic acetylcholine receptor (NRA) group administrated with hexamethonium (10 mg kg⁻¹) before electrical stimulation.

Measurements and main results

The haemodynamics, histopathology of lung tissue, arterial blood gas, lactic acid, tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were measured. Vagus nerve electrical stimulation not only significantly increased the mean arterial pressure (MAP) and heart rate (HR), but also decreased the infiltration of inflammatory cells into interstitial and alveolar spaces after thermal challenge and attenuated TNF-α and IL-6 production. Hexamethonium pre-treatment significantly reversed the effects of vagal electrical stimulation, but atropine administration before electrical stimulation had no such effects.

Conclusions

Direct electrical stimulation of the vagus nerve might produce therapeutic effect on thermal injury. The effect may be realised by limiting the inflammatory response via nicotinic acetylcholine receptors in rats.     

Complications of chronic vagus nerve stimulation for epilepsy in children

OBJECT: The aim of this study was to define better the incidence of surgical complications and untoward side effects of chronic vagus nerve stimulation (VNS) in a population of children with medically refractory epilepsy. METHODS: The authors retrospectively reviewed the cases of 74 consecutive patients (41 male and 33 female) 18 years of age or younger (mean age 8.8 years, range 11 months-18 years) who had undergone implantation of a vagal stimulator between 1998 and 2001 with a minimum follow up of 1 year (mean 2.2 years). Of the 74 patients treated, seven (9.4%) had a complication ultimately resulting in removal of the stimulator. The rate of deep infections necessitating device removal was 3.5% (three of 74 patients who had undergone 85 implantation and/or revision procedures). An additional three superficial infections occurred in patients in whom the stimulators were not removed: one was treated with superficial operative debridement and antibiotic agents and the other two with oral antibiotics only. Another four stimulators (5.4%) were removed because of the absence of clinical benefit and device intolerance. Two devices were revised because of lead fracture (2.7%). Among the cohort, 11 battery changes have been performed thus far, although none less than 33 months after initial implantation. Several patients experienced stimulation-induced symptoms (hoarseness, cough, drooling, outbursts of laughter, shoulder abduction, dysphagia, or urinary retention) that did not require device removal. Ipsilateral vocal cord paralysis was identified in one patient. One patient died of aspiration pneumonia more than 30 days after device implantation. CONCLUSIONS: Vagus nerve stimulation remains a viable option for improving seizure control in difficult to treat pediatric patients with epilepsy. Surgical complications such as hardware failure (2.7%) or deep infection (3.5%) occurred, resulting in device removal or revision. Occasional stimulation-induced symptoms such as hoarseness, dysphagia, or torticollis may be expected (5.4%).     

Image-guided motor cortex stimulation in patients with central pain.

According to recent clinical data, motor cortex stimulation (MCS) is an alternative treatment for central pain syndromes. We present our minimally invasive technique of image guidance for the placement of the motor cortex-stimulating electrode and assess the clinical usefulness of both neuronavigation and vacuum headrest. Five patients suffering from central pain underwent MCS with the guidance of a frameless stereotactic system (BrainLab AG, Munich, Germany). The neuronavigation was used for identification of the precentral gyrus and accurate planning of the single burr hole. The exact location was reconfirmed by an intraoperative stimulation test. Postoperative clinical and neuroradiological evaluations were performed in each patient. The navigation system worked properly in all 5 neurosurgical cases. Determination of the placement of stimulating electrode was possible in every case. All patients obtained postoperative pain relief. No surgical complication occurred, and the postoperative course was uneventful in all patients. This preliminary experience may confirm image guidance as a useful tool for the surgery of MCS. Additionally, minimal and safe exposure can be achieved using a single burr hole and vacuum headrest.     

Electrical stimulation of the vagus nerve enhances cognitive and motor recovery following moderate fluid percussion injury in the rat

Intermittent, chronically delivered electrical stimulation of the vagus nerve (VNS) is an FDA-approved procedure for the treatment of refractory complex/partial epilepsy in humans. Stimulation of the vagus has also been shown to enhance memory storage processes in laboratory rats and human subjects. Recent evidence suggests that some of these effects of VNS may be due to the activation of neurons in the nucleus locus coeruleus resulting in the release of norepinephrine (NE) throughout the neuraxis. Because antagonism of NE systems has been shown to delay recovery of function following brain damage, it is possible that enhanced release of NE in the CNS may facilitate recovery of function. To evaluate this hypothesis the lateral fluid percussion injury (LFP) model of traumatic brain injury was used and a variety of motor and cognitive behavioral tests were employed to assess recovery in pre-trained stimulated, control, and sham-injured laboratory rats. Two hours following moderate LFP, vagus nerve stimulation (30.0-sec trains of 0.5 mA, 20.0 Hz, biphasic pulses) was initiated. Stimulation continued in each animal's home cage at 30-min intervals for a period of 14 days, with the exception of brief periods when the animals were disconnected for behavioral assessments. Motor behaviors were evaluated every other day following LFP and tests included beam walk, locomotor placing, and skilled forelimb reaching. In each measure an enhanced rate of recovery and /or level of final performance was observed in the VNS-LFP animals compared to nonstimulated LFP controls. Behavior in the Morris water maze was assessed on days 11-14 following injury. Stimulated LFP animals showed significantly shorter latencies to find the hidden platform than did controls. Despite these behavioral effects, neurohistological examination did not reveal significant differences in lesion extent, density of fluorojade positive neurons, reactive astrocytes or numbers of spared neurons in the CA3 subarea of the hippocampus, at least at the one time point studied 15 days post-injury. These results support the idea that vagus nerve stimulation enhances the neural plasticity that underlies recovery of function following brain damage and provides indirect support for the hypothesis that enhanced NE release may mediate the effect. Importantly, since VNS facilitated both the rate of recovery and the extent of motor and cognitive recovery, these findings suggest that electrical stimulation of the vagus nerve may prove to be an effective non-pharmacological treatment for traumatic brain injury.