Pharmacological versus microvascular decompression approaches for the treatment of trigeminal neuralgia: clinical outcomes and direct costs

Trigeminal neuralgia

Trigeminal neuralgia (TN) is a facial pain disorder characterized by intense and paroxysmal pain that profoundly affects quality of life and presents complex challenges in diagnosis and treatment. TN can be categorized as classical, secondary and idiopathic. Epidemiological studies show variable incidence rates and an increased prevalence in women and in the elderly, with familial cases suggesting genetic factors. The pathophysiology of TN is multifactorial and involves genetic predisposition, anatomical changes, and neurophysiological factors, leading to hyperexcitable neuronal states, central sensitization and widespread neural plasticity changes. Neurovascular compression of the trigeminal root, which undergoes major morphological changes, and focal demyelination of primary trigeminal afferents are key aetiological factors in TN. Structural and functional brain imaging studies in patients with TN demonstrated abnormalities in brain regions responsible for pain modulation and emotional processing of pain. Treatment of TN involves a multifaceted approach that considers patient-specific factors, including the type of TN, with initial pharmacotherapy followed by surgical options if necessary. First-line pharmacological treatments include carbamazepine and oxcarbazepine. Surgical interventions, including microvascular decompression and percutaneous neuroablative procedures, can be considered at an early stage if pharmacotherapy is not sufficient for pain control or has intolerable adverse effects or contraindications.

Photobiomodulation and vitamin B treatment alleviate both thermal and mechanical orofacial pain in rats

PURPOSE

The present study investigates the efficacy of Photobiomodulation (PBM) and Vitamin B Complex (VBC) to relieve pain, both in separately and combined (PBM and VBC).

METHODS

Rats with chronic constriction injury of the right infraorbital nerve (CCI-IoN) or Sham surgery were used. PBM was administered at a wavelength of 904 nm and energy density of 6.23 J/cm2 and VBC (containing B1, B6 and B12) subcutaneously, both separately and combined. Behavioral tests were performed to assess mechanical and thermal hypersensitivity before and after CCI and after PBM, VBC, or PBM + VBC. The expression of inflammatory proteins in the trigeminal ganglion and the immunohistochemical alterations of Periaqueductal Gray (PAG) astrocytes and microglia were examined following CCI and treatments.

RESULTS

All testeds treatments reversed the painful behavior. The decrease in pain was accompanied by a decrease of Glial Fibrillary Acidic Protein (GFAP), a specific astrocytic marker, and Ionized calcium-binding adaptor molecule 1 (Iba-1), a marker of microglia, and decreased expression of Transient Receptor Potential Vanilloid 1 (TRPV1), Substance P, and Calcitonin Gene-Related Peptide (CGRP) induced by CCI-IoN in PAG and Trigeminal ganglion. Furthermore, both treatments showed a higher expression of Cannabinoid-type 1 (CB1) receptor in the trigeminal ganglion compared to CCI-IoN rats. Our results show that no difference was observed between groups.

CONCLUSION

We showed that PBM or VBC regulates neuroinflammation and reduces inflammatory protein expression. However, the combination of PBM and VBC did not enhance the effectiveness of both therapies alone.

Quality of life after trigeminal nerve block in refractory trigeminal neuralgia: A retrospective cohort study and literature review

OBJECTIVE

To evaluate the effect of trigeminal nerve block (TNB) on patients' quality of life (QOL) 15 days after the procedure in patients with refractory TN.

METHODS

This retrospective observational cohort study involved patients receiving TNB (levobupivacaine, clonidine, corticosteroid) between 2014 and 2018 at a postoperative pain clinic in France. Change in QOL from Day 0 (before block) to Day 15 was assessed according to SF-12.

RESULTS

21 patients (62 ± 14 y) were included in the study. Most patients (71%) were referred following surgery or dentistry. Of the 9 patients (43%) who exhibited >10% increase in SF-12 scores and so were deemed responders, SF12-physical and SF12-mental were increased by mean differences of 17 and 9 points, respectively. The mean duration of block lasted 15 ± 59 days (range 1 to 90 days) and no severe adverse effects were observed.

CONCLUSION

Improved QOL was observed in approximately 50% of patients with trigeminal neuralgia (TN) two weeks after specific nerve block. The technique was easy to administer and well accepted by the patients.

Long term evaluation of a multidisciplinary trigeminal neuralgia service

Background

Trigeminal neuralgia is an episodic severe neuralgic pain and can be managed both medically and surgically. If possible, this should be directed by a Multidisciplinary Team (MDT) of specialised surgeons, physicians, dentists, psychologists and specialist nurses with access to all treatment modalities, which enables patients to make an informed decision about their future management.

Objective

The aim of this study was to review the outcomes of patients managed by an MDT clinic, in a single institute over an eleven-year period.

Methods

A prospective database was used to identify patients with trigeminal neuralgia or its variants who had attended a joint MDT clinic. The electronic notes were examined for demographics, onset and duration of trigeminal neuralgia, medications history, pain scores and details of surgical procedures if any by two independent assessors.

Results

Three hundred thirty-four patients attended the MDT between 2008–2019. Forty-nine of them had surgery before being referred to the service and were included but analysed as a subgroup. Of the remaining patients, 54% opted to have surgery following the MDT either immediately or at a later date. At the last reported visit 55% of patients who opted to have surgery were pain free and off medications, compared to 15.5% of medically managed patients. Surgical complications were mostly attributable to numbness and in the majority of cases this was temporary. All patients who were not pain free, had complications after surgery or opted to remain on medical therapy were followed up in a facial pain clinic which has access to pain physicians, clinical nurse specialists and a tailored pain management program. Regular patient related outcome measures are collected to evaluate outcomes.

Conclusion

An MDT clinic offers an opportunity for shared decision making with patients deciding on their personal care pathway which is valued by patients. Not all patients opt for surgery, and some continue to attend a multidisciplinary follow up program. Providing a full range of services including psychological support, improves outcomes.

Microvascular decompression for typical trigeminal neuralgia: Personal experience with intraoperative neuromonitoring with level-specific-CE-Chirp® brainstem auditory evoked potentials in preventing possible hearing loss

Background:

Permanent hearing loss after posterior fossa microvascular decompression (MVD) for typical trigeminal neuralgia (TTN) is one of the possible complications of this procedure. Intraoperative brainstem auditory evoked potentials (BAEPs) are used for monitoring the function of cochlear nerve during cerebellopontine angle (CPA) microsurgery. Level-specific (LS)-CE-Chirp® BAEPs are the most recent evolution of classical click BAEP, performed both in clinical studies and during intraoperative neuromonitoring (IONM) of acoustic pathways during several neurosurgical procedures.

Methods:

Since February 2016, we routinely use LS-CE-Chirp® BAEPs for monitoring the function of cochlear nerve during CPA surgery, including MVD for trigeminal neuralgia. From September 2011 to December 2018, 71 MVDs for TTN were performed in our department, 47 without IONM of acoustic pathways (Group A), and, from February 2016, 24 with LS-CE-Chirp BAEP (Group B).

Results:

Two patients of Group A developed a permanent ipsilateral anacusia after MVD. In Group B, we did not observe any permanent acoustic deficit after surgery. In one case of Group B, during arachnoid dissection, intraoperative LS-CE-Chirp BAEP showed a temporary lag of V wave, resolved in 5 min after application of intracisternal diluted papaverine (0.3% solution without excipients).

Conclusion:

MVD is widely considered a definitive surgical procedure in the management of TTN. Even though posterior fossa MVD is a safe procedure, serious complications might occur. In particular, the use of IONM of acoustic pathways during MVD for TTN might contribute to prevention of postoperative hearing loss.

Working ability and use of healthcare resources for patients with trigeminal neuralgia treated via microvascular decompression

BACKGROUND

Trigeminal neuralgia (TN) is defined as sudden, usually unilateral, severe, brief, stabbing and recurrent episodes of pain in one or more branches of the trigeminal nerve. In patients with TN refractory to medical therapy, microvascular decompression (MVD) is considered. TN interferes with daily functioning and is associated with depression and anxiety. Direct costs of MVD are high, but the procedure is believed to improve working ability and reduce the use of medical resources. This study aims to analyse MVD's effects on TN patients regarding work capacity, healthcare utilisation and health-related quality of life (hrQoL).

METHODS

We conducted a cross-sectional survey of patients who underwent MVD for TN between 2007 and 2016 (n = 46). The patients' outcome, work capacity and use of medical resources were assessed via the Barrow Neurological Institute Pain Intensity Score (BNI Score), with questions regarding patients' employment status, restrictions in work capacity, healthcare utilisation and completion of the EQ5D questionnaire.

RESULTS

The response rate was 28/46 (61%). The majority of the participants (20/28) reported feeling strongly/quite handicapped in productivity due to TN preoperatively, which was also indicated by a few participants (3/28) postoperatively (p = < 0.01). Pain-related days off work were reduced postoperatively from 21 to 4 (p = 0.059) on average. Postoperative hrQoL did not differ from the general German population. Further reductions in healthcare utilisation and private costs were shown.

CONCLUSION

In TN, MVD alleviates patient burden, especially concerning productivity and the consumption of health resources.

Efficacy and safety of CT-guided percutaneous pulsed radiofrequency treatment of the Gasserian ganglion in patients with medically intractable idiopathic trigeminal neuralgia

Background

There is a lack of prospective studies for the long-term results of percutaneous pulsed radiofrequency (PRF) of the Gasserian ganglion in the treatment of patients with medically refractory trigeminal neuralgia (TN).

Methods and results

We prospectively observed the outcomes of 28 idiopathic TN patients (between July 2013 and July 2016) who received CT-guided percutaneous PRF treatment of the Gasserian ganglion. All of the patients had stopped responding to drug therapy before PRF treatment. The effective treatment standard was a reduction in the pain numeric rating scale (NRS) by ≥50% after the procedure. The postoperative NRS score decreased gradually from preoperative 7.6±0.8 months to 1.5±2.4, 0.2±0.4, 0.2±0.4, 0.1±0.4, and 0.1±0.4 at 1, 3, and 6 months and 1 and 2 years after the PRF treatment. The response rates at 1, 3, and 6 months were 85.7%, and the rates at 12 months and 2 years were maintained at 78.6%. No serious side effects were observed.

Conclusion

CT-guided PRF invention is an effective and safe technique for medically intractable idiopathic TN patients. This minimally invasive alternative treatment has the potential as a first-line therapy for TN.

Stevens-Johnson Syndrome following Failure of Genetic Screening prior to Carbamazepine Prescription

Failure to screen susceptible individuals for human leucocyte allele B∗1502 leads to the onset of Stevens-Johnson syndrome (SJS). We report a case of a 27-year-old Malay female who was treated with carbamazepine following the diagnosis of trigeminal neuralgia without a genetic screening. She was prescribed 150 mg of carbamazepine initially and the dose was increased to 300 mg following the initial dose. A sudden development of skin and mucous membrane ulcers was observed and this warranted immediate hospitalization. A diagnosis of SJS was made and she was treated immediately with intravenous corticosteroids. Genetic screening prior to carbamazepine prescription is essential especially in susceptible populations.

Gabapentin alleviates affective pain after traumatic nerve injury

Gabapentin reduces behavioral signs of stimulus-evoked allodynia and hyperalgesia in preclinical studies of traumatic nerve injury, but its effects on more clinically relevant measures of stimulus-independent pain are unclear. To address this gap, we determined whether gabapentin would relieve affective pain after spared nerve injury (SNI). Twelve days after sham or SNI surgery, we administered gabapentin over three consecutive conditioning days and then evaluated conditioned place preference. Gabapentin produced conditioned place preference and reversed mechanical hypersensitivity in SNI but not sham rats at a dose (100 mg/kg) that did not change open-field activity. These results show for the first time that gabapentin provides relief from affective pain without producing sedation, and add to the limited clinical literature suggesting that its use can be extended to treat pain arising from traumatic nerve injury.

Effect of carbamazepine and gabapentin on excitability in the trigeminal subnucleus caudalis of neonatal rats using a voltage-sensitive dye imaging technique

Background

The antiepileptic drugs carbamazepine and gabapentin are effective in treating neuropathic pain and trigeminal neuralgia. In the present study, to analyze the effects of carbamazepine and gabapentin on neuronal excitation in the spinal trigeminal subnucleus caudalis (Sp5c) in the medulla oblongata, we recorded temporal changes in nociceptive afferent activity in the Sp5c of trigeminal nerve-attached brainstem slices of neonatal rats using a voltage-sensitive dye imaging technique.

Results

Electrical stimulation of the trigeminal nerve rootlet evoked changes in the fluorescence intensity of dye in the Sp5c. The optical signals were composed of two phases, a fast component with a sharp peak followed by a long-lasting component with a period of more than 500 ms. This evoked excitation was not influenced by administration of carbamazepine (10, 100 and 1,000 μM) or gabapentin (1 and 10 μM), but was increased by administration of 100 μM gabapentin. This evoked excitation was increased further in low Mg²⁺ (0.8 mM) conditions, and this effect of low Mg²⁺ concentration was antagonized by 30 μM DL-2-amino-5-phosphonopentanoic acid (AP5), a N-methyl-d-aspartate (NMDA) receptor blocker. The increased excitation in low Mg²⁺ conditions was also antagonized by carbamazepine (1,000 μM) and gabapentin (100 μM).

Conclusion

Carbamazepine and gabapentin did not decrease electrically evoked excitation in the Sp5c in control conditions. Further excitation in low Mg²⁺ conditions was antagonized by the NMDA receptor blocker AP5. Carbamazepine and gabapentin had similar effects to AP5 on evoked excitation in the Sp5c in low Mg²⁺ conditions. Thus, we concluded that carbamazepine and gabapentin may act by blocking NMDA receptors in the Sp5c, which contributes to its anti-hypersensitivity in neuropathic pain.