Trigeminal pain under vagus nerve stimulation

An Unusual Cause of Ear Pain. A Life Threatening Disease Revealed by a Common Symptom

A 40-year-old woman presented to the emergency department (ED) for bilateral otalgia as her sole complaint. The physician's otoscopic examination was normal and the rest of the examination was unremarkable except for previously unknown high blood pressure. The patient had no chest pain or dyspnea. She was discharged from the ED with antihypertensive therapy, pain-relief medications, and an appointment with a cardiologist. Twelve days later, transthoracic echocardiography revealed pericardial effusion and dilated ascending aorta. Computed tomography scan finally diagnosed an aortic dissection (AD) type A (Stanford classification) which necessitated emergency surgery.

Late-onset jaw and teeth pain mimicking trigeminal neuralgia associated with chronic vagal nerve stimulation: case series and review of the literature

BACKGROUND

Vagal nerve stimulation (VNS) for refractory epilepsy is well established. Trigeminal neuralgia itself is a common disease in adults, and thus, late-onset pain in the trigeminal region under VNS, which is extremely rare, may not be recognized as caused by VNS.

CASE PRESENTATION

Two patients with drug-resistant symptomatic epilepsy treated with chronic VNS experienced stimulation-related pain in the lower and upper jaw and teeth on the side of stimulation. No evidence of local spread of the stimulation current was present. The pain started with a delay of years after device implantation and weeks after the last increase in the pacing parameters. At the time of onset, the pain was not recognized as VNS-related, leading to extensive examinations. The trigeminal neuralgia-like pain resolved after adjustment of the stimulation current intensity. In one of the patients, the pain disappeared within one to two days following every epileptic seizure. To our knowledge, this is the first case report of late-onset trigeminal pain under VNS revealing a direct link between epileptogenic and pain processes.

CONCLUSION

A painless interval between the last change of the pacing parameters and trigeminal pain can lead to the erroneous interpretation that this is a typical trigeminal neuralgia. The lack of its recognition as a side effect of VNS can lead to unnecessary examinations and delayed adjustment of stimulation parameters. In patients with signs of late-onset trigeminal pain under VNS with normal electrode impedance and no evidence of local current spread, the replacement of the VNS lead does not seem to be beneficial. A review of the literature on VNS side effects including pain and device malfunctions was undertaken.

[Vagus nerve stimulation therapy in epilepsy patients: long-term outcome and adverse effects: a retrospective analysis]

BACKGROUND

Vagus nerve stimulation (VNS) is one of the numerous stimulation procedures used in the treatment of neurological diseases in which there has been growing interest in recent years. Since 1988 it has been frequently used in the therapy of epilepsies but the mechanism of action is still unknown. It is considered to be low in adverse effects.

TOPICS

Decision-making process on VNS therapy as well as long-term outcome and adverse effects.

METHOD

Retrospective analysis of all 62 patients treated over a long period by VNS in the Epilepsy Center of the University Hospital of Freiburg (Germany) from 1 August 2002 through 4 January 2011.

RESULTS

OUTCOME

the results show that 2 out of 62 patients became seizure-free under VNS therapy while maintaining the already existing anti-ictal medication and 4 more patients under VNS plus dosage increase of the already existing medication and/or new medication. However, in 34 out of 62 patients VNS therapy did not improve the seizure situation. Adverse effects: VNS is not as low in adverse effects as is generally considered. Only 9 out of 62 patients did not show any adverse effects and on the other hand severe, even life-threatening adverse effects also occurred.

CONCLUSION

Patients undergoing VNS therapy have to be carefully checked for possible adverse effects, not only at the beginning of VNS therapy but also in the long-term course. These results have to be considered in the cost-benefit analysis of this treatment.

[Treatment of epilepsy: peripheral and central stimulation techniques]

The efficacy of electrical stimulation in the treatment of epileptic seizures was demonstrated experimentally even in the 1970s. Clinical studies have proven the efficacy of vagus nerve stimulation and in recent years also of stimulation of the trigeminal nerve, the anterior nucleus of the thalamus and of the epileptic focus in treating focal epilepsy. Mechanisms of action depend on the stimulation site and parameters and include activation of endogenous antiepileptic nuclei, modulation of propagation of epileptic activity and suppression of ictal activity at the site of generation. Based on available data the tolerability of peripheral and central brain stimulation appears to be good but experiences from wider clinical use are still lacking.

Vagus nerve stimulation therapy (VNST) in epilepsy - implications for dental practice

Epilepsy is a chronic condition which affects about 1% of the population. It is important that the dental team is aware of the management of epileptic seizures and epileptic syndromes including recent advances in seizure management. As people with epilepsy often get a warning aura before seizures begin, the management of the condition has increasingly involved measures to prevent the seizure, once the aura has begun. Vagus nerve stimulation therapy (VNST) in epilepsy involves the use of an implantable electronic device and is being increasingly used in the UK to control severe treatment resistant epilepsy. As a result, more patients will be presented to clinicians in the primary healthcare setting and hospital services with these devices in place. Members of the dental team need to understand the principles of epilepsy control, how VNST is used in the management of intractable epilepsy, how the VNST system operates and the implications of VNST use for dental practice including medical devices, interactions and safety features.

Insulation discontinuity in a vagus nerve stimulator lead: a treatable cause of intolerable stimulation-related symptoms

Discontinuity in the silicone insulation over an electrode of a left vagus nerve stimulator (VNS) allowed the aberrant leak of current to the phrenic nerve and other structures. This resulted in ipsilateral diaphragmatic dysfunction, inability to vocalize, and severe radiating pain into the jaw and upper incisor for the duration of each stimulation. The device was explanted and a new device was implanted. All stimulation-related symptoms ceased immediately.

A similar discontinuity in the silicone insulation is the likely explanation for several prior reports of poorly understood pains and phrenic nerve stimulation in patients with VNSs. The findings and analysis of this case establish a rationale for consideration of replacement of the VNS lead in all similarly symptomatic patients.