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.     

Efficacy of vagus nerve stimulation for epilepsy by patient age, epilepsy duration, and seizure type

Medically refractory epilepsy is a morbid condition, and many patients are poor candidates for surgical resection because of multifocal seizure origin or eloquence near epileptic foci. Vagus nerve stimulation (VNS) was approved in 1997 by the US Food and Drug Administration as an adjunctive treatment of intractable epilepsy for individuals aged 12 years and more with partial epilepsy. Controversy persists regarding the efficacy of VNS for epilepsy and about which patient populations respond best to therapy. In this article, the authors retrospectively studied a patient outcome registry and report the largest, to their knowledge, analysis of VNS outcomes in epilepsy.     

Cervical epidural analgesia via a thoracic approach using nerve stimulation guidance in an adult patient undergoing elbow surgery

OBJECTIVE: This case report describes the placement of a cervical epidural catheter via the thoracic approach, using nerve stimulation, in a patient undergoing elbow surgery. CASE REPORT: An epidural catheter was easily advanced to the C5 dermatome level from the T4-5 interspace, using nerve stimulation guidance. Successful perioperative analgesia was accomplished using an infusion of ropivacaine 0.2% with 0.05 mg/mL morphine at 4 mL/h. CONCLUSIONS: This case report suggests that electrical stimulation may allow one to accurately position epidural catheters in the central neuraxial space to provide reliable, effective analgesia of the upper extremity. This approach might be an alternative way to deliver cervical epidural analgesia for patients undergoing upper extremity surgery.     

Lateral cervical epidural catheter placement using nerve stimulation for continuous unilateral upper extremity analgesia following a failed continuous peripheral nerve block

This case report describes the application of electrical stimulation (Tsui test) to confirm placement of a cervical epidural catheter for postoperative pain management in a patient with a failed brachial plexus block who underwent upper extremity surgery. An epidural catheter was easily advanced under nerve stimulation guidance to the surgical dermatome C4 level without any resistance from the C7-T1 level. Successful analgesia was achieved with a bolus of 2 mg ml(-1) ropivacaine 2 ml and fentanyl 20 microg, followed by a continuous infusion of 2 mg ml(-1) ropivacaine with 2 microg ml(-1) of fentanyl at a rate of 2 ml h(-1). This case reminds the clinician that cervical epidural analgesia may serve as an alternative to a difficult continuous peripheral nerve block. Electrical stimulation may also help to confirm cervical epidural catheter placement at the appropriate dermatome to provide effective analgesia with minimal side-effects.     

Optimal Vagus Nerve Stimulation Frequency for Suppression of Spike‐and‐Wave Seizures in Rats

Vagus nerve stimulation (VNS) is used as an adjunctive therapy for drug‐resistant epilepsy and results in a 50% seizure reduction in up to 50% of treated patients. The VNS frequency used in the clinic today is in the range of 10–30 Hz. The evidence for choosing the stimulation frequency is limited, and little knowledge is available on the effect of other VNS frequencies. Deep brain, trigeminal nerve, or spinal cord stimulation studies have suggested the use of stimulation frequencies above 80 Hz for seizure control. Therefore, our objective for the present study was to investigate if VNS using frequencies higher than those currently used in the clinic could be more effective in attenuating seizures. Spike‐and‐wave (SW) discharges were induced in 11 rats, which then were subjected to VNS sessions applied at the frequencies of 10, 30, 80, 130, and 180 Hz combined with control intervals without stimulation. The anticonvulsive effect of VNS was evaluated by comparing the normalized mean power (nMP) and frequency (nMSF) of the SW discharges derived from intracortical recordings collected during the stimulation and control intervals. Compared with the control intervals, all the tested VNS frequencies significantly reduced the nMP (in the range of 9–21%). However, we found that 130 and 180 Hz VNS induced a 50% larger attenuation of seizures than that achieved by 30 Hz VNS. In addition, we found that 80, 130, and 180 Hz VNS induced a significant reduction of the nMSF, that is by 5, 7, and 8%, respectively. These results suggest that a VNS stimulation frequency in the range of 130–180 Hz may be more effective in inhibiting seizures than the 30 Hz VNS applied in the clinic today.     

Experience with vagus nerve stimulation for intractable epilepsy: some questions and answers.

Vagus nerve stimulation (VNS) is gaining increasing popularity and credibility as a treatment option for patients with intractable epilepsy. VNS is a relatively recent innovation, however, and like many other incipient developments, it has engendered a number of unresolved controversies and perplexities. Limitations in our current understanding of how VNS works lie at the crux of these uncertainties. In this article, we present our clinical experience with VNS and review the fundamental issue which remain unsettled, such as the mechanism of VNS action, the factors underlying variability in patient outcome, and the selection of ideal candidates for VNS therapy. Although many enigmas persist, VNS has proven to be a safe, feasible, and potentially effective method of reducing seizures in select patient populations. It offers several advantages over extant treatments and, as a result, holds much promise for future therapy of medically refractory epilepsy.     

Vagus nerve stimulation for the management of seizures in children: an 8-year experience

Background

Medication-resistant seizure disorder is a challenging, debilitating, and expensive condition. Although multiple interventions are now available, none is universally effective. In 1997, vagus nerve stimulation (VNS) was approved for treatment of refractory seizures in patients older than 12 years. Vagus nerve stimulation has shown some benefit for these individuals, but less is known about its use in patients younger than 12 years. This review analyzes the safety and efficacy of VNS in young children.

Methods

From March 2000 to February 2008, patients with medication-resistant seizures were implanted with a neurocybernetic prosthesis. Two weeks later, the device was activated. The children were followed for at least 3 months, and adjustments were made. Retrospective chart review was performed to collect data.

Results

Of 28 patients, the mean age at implantation was 8 years and 5 months. Twenty-one (75%) children were younger than 12 years. There were no surgical complications. Two children were reimplanted for lead malfunction, and 4 generators were replaced. Two children had transitory adverse effects (hoarseness and stridor). Mean follow-up was 3 years and 5 months. At 1 year, 52% of children had greater than 50% reduction in seizures.

Conclusions

Although the effectiveness of VNS is variable and unpredictable, safety is high even in young children. Because of the potential benefit for these complex patients, the implantation of this nerve stimulation device should be included in the armamentarium of pediatric surgeons.     

Vagus Nerve Stimulation Therapy: Indications,Programing, and Outcomes

Vagus nerve stimulation (VNS) provides palliation of seizure reduction for patients with medically refractory epilepsy. VNS is indicated for symptomatic localization-related epilepsy with multiple and bilateral independent foci, symptomatic generalized epilepsy with diffuse epileptogenic abnormalities, refractory idiopathic generalized epilepsy, failed intracranial epilepsy surgery, and other several reasons of contraindications to epilepsy surgery. Programing of the parameters is a principal part in VNS. Output current and duty cycle should be adjusted to higher settings particularly when a patient does not respond to the initial setting, since the pivotal randomized trials performed in the United States demonstrated high stimulation made better responses in seizure frequency. These trials revealed that a ≥ 50% seizure reduction occurred in 36.8% of patients at 1 year, in 43.2% at 2 years, and in 42.7% at 3 years in 440 patients. Safety of VNS was also confirmed because side effects including hoarseness, throat discomfort, cough, paresthesia, and headache improved progressively during the period of 3 years. The largest retrospective study with 436 patients demonstrated the mean seizure reduction of 55.8% in nearly 5 years, and also found 75.5% at 10 years in 65 consecutive patients. The intermediate analysis report of the Japan VNS Registry showed that 60% of 164 cases got a ≥ 50% seizure reduction in 12 months. In addition to seizure reduction, VNS has positive effects in mood and improves energy level, memory difficulties, social aspects, and fear of seizures. VNS is an effective and safe option for patients who are not suitable candidates for intracranial epilepsy surgery.     

Role of afferent neural input in regression of sensory paralysis during epidural analgesia.

This study was designed to determine the role of the afferent peripheral neural input in the regression of sensory analgesia during epidural analgesia. Eighteen patients who underwent minor obstetric or gynecologic surgery under lumbar epidural analgesia with lidocaine were divided into three groups. Group A received electrical single twitch stimulation at the spinal nerve dermatome one segment rostrad of the proximal extent of sensory paralysis. Group B received electrical twitch stimulation at the anterior crural region where nerve block may have been most profound in this study. Group C was assigned as a control and did not receive any stimulation. The patients received the stimulation for 60 min (i.e., from 80 to 140 min after the epidural injection). The range of sensory analgesia at 140 min was compared with that at 80 min. The regression of sensory analgesia in group B or C was 1 +/- 0 (mean +/- SD) spinal nerve segments, but in group A it was 5 +/- 1, which was significantly (P less than 0.0025) larger than the others. We conclude that the afferent peripheral neural input to a spinal segment where the nerve block is incomplete may accelerate the regression of sensory analgesia from epidural analgesia.     

Vagus nerve stimulation for epilepsy: a meta-analysis of efficacy and predictors of response

Vagus nerve stimulation (VNS) was approved by the US FDA in 1997 as an adjunctive treatment for medically refractory epilepsy. It is considered for use in patients who are poor candidates for resection or those in whom resection has failed. However, disagreement regarding the utility of VNS in epilepsy continues because of the variability in benefit reported across clinical studies. Moreover, although VNS was approved only for adults and adolescents with partial epilepsy, its efficacy in children and in patients with generalized epilepsy remains unclear. The authors performed the first meta-analysis of VNS efficacy in epilepsy, identifying 74 clinical studies with 3321 patients suffering from intractable epilepsy. These studies included 3 blinded, randomized controlled trials (Class I evidence); 2 nonblinded, randomized controlled trials (Class II evidence); 10 prospective studies (Class III evidence); and numerous retrospective studies. After VNS, seizure frequency was reduced by an average of 45%, with a 36% reduction in seizures at 3-12 months after surgery and a 51% reduction after > 1 year of therapy. At the last follow-up, seizures were reduced by 50% or more in approximately 50% of the patients, and VNS predicted a ≥ 50% reduction in seizures with a main effects OR of 1.83 (95% CI 1.80-1.86). Patients with generalized epilepsy and children benefited significantly from VNS despite their exclusion from initial approval of the device. Furthermore, posttraumatic epilepsy and tuberous sclerosis were positive predictors of a favorable outcome. In conclusion, VNS is an effective and relatively safe adjunctive therapy in patients with medically refractory epilepsy not amenable to resection. However, it is important to recognize that complete seizure freedom is rarely achieved using VNS and that a quarter of patients do not receive any benefit from therapy.     

Usefulness of epidural nerve stimulation to confirm epidural catheter placement

An epidural catheter must be placed in epidural space correctly to give sufficient epidural anesthesia for patients. Recently, as a technique to confirm the catheter placement, electrical stimulation of epidural nerve using an inserted epidural catheter was introduced. This study was conducted to evaluate the reliability of this simple technique in 13 patients. Immediately after an epidural catheter (19 G Arrow Flextip Plus) was placed, an adapter with electrode (Arrow-Johans ECG Adapter) was attached to its connector and nerve stimulation was performed using a peripheral nerve stimulator (1 Hz, 10 mA). Catheter placement was judged to be correct by both presence of muscle contraction in response to stimulation and occurrence of analgesia after the administration of a local anesthetic. In 5 patients, additional roentgen examinations were performed to identify the positions of catheters. In all patients except one, muscle contraction was observed by stimulation, and analgesia was confirmed in all patients after the injection of an anesthetic. X-ray examinations revealed that the tip of catheter placed at the vertebral level corresponded with the spinal segmental level where muscle movement occurred. Our study demonstrates that nerve stimulation can be a reliable method to confirm epidural catheter placement. Our results also suggest that the position of catheter tip can be estimated easily using this technique.     

Neurologische postpartale Komplikationen nach geburtshilflicher Periduralanalgesie Fallbericht und Literaturübersicht

Regional analgesia provides effective pain relief during delivery. Postpartal neurological deficits may be due to pressure of the fetal head on nerve structures at the pelvic rim or may be a complication of epidural analgesia. Nerve injuries due to spontaneous delivery and instrumental delivery are much more common than neurological deficits from epidural analgesia such as epidural hematoma or epidural abscess. The pattern of nerve damage is usually unilateral and non segmental. This case report describes the differential diagnosis of neurological deficit after spontaneous delivery under epidural analgesia and a discussion of the recent literature. Finally recommendations for the treatment of neurological deficits after delivery under epidural analgesia are presented.     

A case report of Vagus nerve stimulation for intractable hiccups

IntroductionIntractable hiccups frequently result from an underlying pathology and can cause considerable illness in the patients. Initial remedies such as drinking cold water, induction of emesis, carotid sinus massage or Valsalva manoeuvre all seem to work by over stimulating the Vagus nerve. Pharmacotherapy with baclofen, gabapentin and other centrally and peripherally acting agents such as chlorpromazine and metoclopramide are reserved as second line treatment. Medical refractory cases even indulge in unconventional therapies such as hypnosis, massages and acupuncture. Surgical intervention, although undertaken very rarely, predominantly revolves around phrenic nerve crushing, blockade or pacing. A novel surgical strategy is emerging in the form of Vagus nerve stimulator (VNS) placement with three cases cited in literature to date with varying degrees of success. Here the authors report a case of VNS placement for intractable hiccups with partial success, in accordance with SCARE-2018 guidelines.Presentation of the caseAn 85-year-old gentleman with a 9-year history of intractable hiccups secondary to pneumonia came to our hospital. The hiccups were symptomatic causing anorexia, insomnia, irritability, depression, exhaustion, muscle wasting and weight loss. The patient underwent countless medical evaluations. All examinations and investigations yielded normal results. The patient underwent aggressive pharmacotherapy, home remedies and unconventional therapies for intractable hiccups but to no avail. He also underwent left phrenic nerve blocking and resection without therapeutic success. The patient presented to our hospital and decision for VNS insertion was taken for compassionate reasons considering patient morbidity. The patient demonstrated significant improvement in his symptoms following VNS insertion.DiscussionA temporary hiccup is an occasional happening experienced by everyone. However, intractable hiccups are associated with significant morbidity and often mortality. Several medical, pharmacological, surgical and novel treatment options are available for intractable hiccups.ConclusionVNS insertion is a novel surgical option for the treatment of intractable hiccups.     

Vagal nerve stimulation: overview and implications for anesthesiologists

Vagal nerve stimulation is an important adjunctive therapy for medically refractory epilepsy and major depression. Additionally, it may prove effective in treating obesity, Alzheimer's disease, and some neuropsychiatic disorders. As the number of approved indications increases, more patients are becoming eligible for surgical placement of a commercial vagal nerve stimulator (VNS). Initial VNS placement typically requires general anesthesia, and patients with previously implanted devices may present for other surgical procedures requiring anesthetic management. In this review, we will focus on the indications for vagal nerve stimulation (both approved and experimental), proposed therapeutic mechanisms for vagal nerve stimulation, and potential perioperative complications during initial VNS placement. Anesthetic considerations during initial device placement, as well as anesthetic management issues for patients with a preexisting VNS, are reviewed.     

The risks of overly effective postoperative epidural analgesia

Continuous epidural analgesia is frequently used to provide supplemental postoperative pain control. Epidural analgesia has the potential to mask the early symptoms that signal impending complications after even routine surgical procedures. We report a case of sciatic nerve palsy following epidural anesthesia after an uncomplicated leg length correction. Good epidural anesthesia may remove a patient's normal protective sensation, allowing pain and other signs of nerve compression from prolonged unchanged postoperative positioning to go unnoticed. This case highlights the need for heightened awareness of potential neurologic compromise in the setting of epidural analgesia. We recommend closely monitoring the patient's neurologic condition and frequently evaluating the patient's position in bed.     

Self-inflicted vocal cord paralysis in patients with vagus nerve stimulators. Report of two cases

Vagus nerve stimulation for treatment of epilepsy is considered safe; reports of severe complications are rare. The authors report on two developmentally disabled patients who experienced vocal cord paralysis weeks after placement of a vagus nerve stimulator. In both cases, traction injury to the vagus nerve resulting in vocal cord paralysis was caused by rotation of the pulse generator at the subclavicular pocket by the patient. Traumatic vagus nerve injury caused by patients tampering with their device has never been reported and may be analogous to a similar phenomenon reported for cardiac pacemakers in the literature. As the use of vagus nerve stimulation becomes widespread it is important to consider the potential for this adverse event.     

Síndrome de Horner e parestesia do território do nervo trigêmeo secundário a analgesia peridural para trabalho de parto

Currently, epidural analgesia is a common procedure for labor analgesia. Although it is considered a safe technique, it is not without complications. Horner's syndrome and paresthesia within the trigeminal nerve distribution are rare complications of epidural analgesia. We report a case of a pregnant woman who developed Horner's syndrome and paresthesia within the distribution of the trigeminal nerve following epidural analgesia for the relief of labor pain.     

Recent Advancement of Technologies and the Transition to New Concepts in Epilepsy Surgery

Fruitful progress and change have been accomplished in epilepsy surgery as science and technology advance. Stereotactic electroencephalography (SEEG) was originally developed by Talairach and Bancaud at Hôspital Sainte-Anne in the middle of the 20th century. SEEG has survived, and is now being recognized once again, especially with the development of neurosurgical robots. Many epilepsy centers have already replaced invasive monitoring with subdural electrodes (SDEs) by SEEG with depth electrodes worldwide. SEEG has advantages in terms of complication rates as shown in the previous reports. However, it would be more indispensable to demonstrate how much SEEG has contributed to improving seizure outcomes in epilepsy surgery. Vagus nerve stimulation (VNS) has been an only implantable device since 1990s, and has obtained the autostimulation mode which responds to ictal tachycardia. In addition to VNS, responsive neurostimulator (RNS) joined in the options of palliative treatment for medically refractory epilepsy. RNS is winning popularity in the United States because the device has abilities of both neurostimulation and recording of ambulatory electrocorticography (ECoG). Deep brain stimulation (DBS) has also attained approval as an adjunctive therapy in Europe and the United States. Ablative procedures such as SEEG-guided radiofrequency thermocoagulation (RF-TC) and laser interstitial thermal therapy (LITT) have been developed as less invasive options in epilepsy surgery. There will be more alternatives and tools in this field than ever before. Consequently, we will need to define benefits, indications, and limitations of these new technologies and concepts while adjusting ourselves to a period of fundamental transition in our foreseeable future.     

Electrical Stimulation in Epilepsy: Vagus Nerve and Brain Stimulation

Vagus nerve stimulation (VNS) for epilepsy is a well established and effective treatment for medically intractable epilepsy. VNS is indicated if resective epilepsy surgery is unsuccessful or is not an option. About 50% of patients with VNS have a seizure reduction greater than 50%, but less than 10% become seizure-free. VNS also has an alerting effect on patients and may allow a reduction in sedating medications. The major adverse event is hoarseness, but treatment is generally well tolerated. The therapeutic effect can be delayed: patients may improve several months after VNS implantation. Direct brain stimulation (DBS) is an emerging treatment for epilepsy. Scheduled stimulation is similar to brain stimulation in Parkinson’s disease. Only the anterior thalamic nucleus has been studied in a larger randomized, controlled trial, in which patients with the stimulator turned on had a significantly reduced seizure frequency. Responsive stimulation applies an electrical stimulus at the site of seizure onset to terminate the seizure if one occurs. The seizure-onset zone must be well defined before implantation. Responsive stimulation requires seizure detection and application of a stimulus online. A large pivotal trial showed a significant reduction in seizure frequency. Both DBS and responsive neurostimulation are well tolerated, but there has been some concern about depression with DBS. Infection, hemorrhage, and lead breakage are adverse events possible with any type of stimulator. None of the brain stimulation devices have been approved by the US Food and Drug Administration, but final approval is expected soon. These devices are indicated for patients with bilateral seizure onset or seizure onset in eloquent areas. Although the initial trials of brain stimulation do not show overwhelming improvement in seizure frequency, the technology will improve with time as we continue to learn about the use of brain stimulation for epilepsy. Optimization of VNS has been going on for 10 years, and we need to ensure that brain stimulation is similarly developed further. In addition, sophisticated devices such as responsive neurostimulators can greatly enhance our understanding of the pathophysiology of epilepsy.     

Horner's syndrome and trigeminal nerve palsy after lumbar epidural analgesia for labor and delivery

This report highlights transient Horner's syndrome and trigeminal nerve palsy following labor epidural analgesia. A 29-year-old primigravida had a lumbar epidural catheter placed for analgesia in labor. The analgesia was maintained by infusion of a dilute local anesthetic/opioid mixture and turned off after achieving complete cervical dilation. Approximately 1 hour after delivery she complained of heaviness in her left eyelid, and was noted to have left-sided ptosis and paresthesia within the distribution of the ophthalmic and maxillary divisions of the trigeminal nerve, which resolved over the next 2 hours. There were no other neurologic changes. Horner's syndrome and cranial nerve palsies can occur as a consequence of epidural analgesia for labor.