Radiosurgical Management of Trigeminal Neuralgia

Frameless image-guided linear accelerator (LINAC) stereotactic radiosurgery for medically refractory trigeminal neuralgia: Clinical outcomes in 116 patients

Background

Frameless image-guided radiosurgery (IGRS) is an effective and non-invasive method of treating patients who are unresponsive to medical management for trigeminal neuralgia (TN). This study evaluated the use of frameless IGRS to treat patients with medically refractory TN.

Methods

We performed a retrospective review of records of 116 patients diagnosed with TN who underwent frameless IGRS using a linear accelerator (LINAC) over 10 years (March 2012-February 2023). All patients had failed medical management for TN. Facial pain was graded using the Barrow Neurological Institute (BNI) scoring system. Each patient received a BNI score before frameless IGRS and following treatment. Failure was defined as a BNI score IV-V at the last follow-up and/or undergoing a salvage procedure following IGRS.

Results

All patients had a BNI score of either IV or V before the frameless IGRS. The mean follow-up duration for all 116 patients following IGRS was 44.1 months. Most patients (81 [69.8%]) had not undergone surgery (microvascular decompression [MVD] or rhizotomy) or stereotactic radiosurgery (SRS) for TN before frameless IGRS. A total of 41 (35.3%) patients underwent a salvage procedure (MVD, rhizotomy, or an additional IGRS) following frameless IGRS. The mean duration between the initial frameless IGRS and salvage procedure was 20.1 months. At the last follow-up, a total of 110 (94.8%) patients had a BNI score of I-III. No complications were reported after the frameless IGRS. The BNI score at the last follow-up was lower compared to the initial BNI for patients regardless of prior intervention (P < 0.001). Patients who failed IGRS had a higher BNI score at the last follow-up compared to those who did not fail IGRS (2.8 vs. 2.5, P = 0.05). Patients with pain relief had a shorter follow-up compared to those with pain refractory to SRS (38.0 vs. 55.1, P = 0.005).

Conclusion

In this large cohort of patients with medically refractory TN, frameless IGRS resulted in durable pain control in the majority of patients without any toxicity.

Understanding radiation-generated electronic traps in radiation dosimeters based on organic field-effect transistors

Organic dosimeters offer unique advantages over traditional technologies, and they can be used to expand the capabilities of current radiation detection systems. In-depth knowledge of the mechanisms underlying the interaction between radiation and organic materials is essential for their widespread adoption. Here, we identified and quantitatively characterized the electronic traps generated during the operation of radiation dosimeters based on organic field-effect transistors. Spectral analysis of the trap density of states, along with optical and structural studies, revealed the origin of trap states as local structural disorder within the crystalline films. Our results provide new insights into the radiation-induced defects in organic dosimeters, and pave the way for the development of more efficient and reliable radiation detection devices.

[Trigeminal Neuralgia - What Do We Know about the Causes, Diagnosis and Treatment?]

Trigeminal Neuralgia - What Do We Know about the Causes, Diagnosis and Treatment? Abstract. Classical trigeminal neuralgia is typically characterized by a stimulus-evoked, recurrent and intense short-lasting stabbing pain in the innervation area of the trigeminal nerve. Its intensity is among the most severe pain imaginable in humans, and yet it is often misdiagnosed and undertreated. Triggers are common activities of daily life like talking or eating. The classical trigeminal neuralgia is due to a neurovascular compression at the nerve root entry zone. The secondary form is related to an underlying neurological disease (caused for example by multiple sclerosis or compression by a brain tumor); the etiology of the idiopathic trigeminal neuralgia is unknown. Treatment options include both medication (mostly antiepileptic drugs) and escalated interventional approaches (microvascular decompression, neurolesional percutaneous procedures, neuromodulative therapeutic options and radiosurgery).

Body mass index and response to stereotactic radiosurgery in the treatment of refractory trigeminal neuralgia: A retrospective cohort study

Stereotactic radiosurgery (SRS) is used as a noninvasive treatment option for patients with trigeminal neuralgia (TN), but the effect of obesity on pain relief post SRS, if any, is unknown. The primary goal of our study was to evaluate the association between obesity and response to SRS in patients with TN. We conducted an IRB-approved retrospective review of patients treated with SRS for TN between 2010 and 2017. Barrow Neurologic Institute (BNI) Score was assigned pre-and post-SRS to quantify pain level. Thirty-two patients (65% female) between the ages of 24 and 96 were studied with a median follow-up time of 11 months. Patients with BMI >25 were significantly less likely to have improvement in their symptoms with SRS (p = 0.005). Elevated BMI may be associated with worsened response to SRS in the treatment of TN.

Computed Tomography Cisternography for Evaluation of Trigeminal Neuralgia When Magnetic Resonance Imaging Is Contraindicated: Case Report and Review of the Literature

BACKGROUND

Trigeminal neuralgia (TGN) causes severe unilateral facial pain. The etiology is hypothesized to be segmental demyelination of the trigeminal nerve root via compression by the superior cerebellar artery (SCA). Microvascular decompression (MVD) allows immediate and long-term pain relief. Preoperative evaluation includes magnetic resonance imaging (MRI) and/or magnetic resonance angiography of the brain. Having a pacemaker is a contraindication for MRI. There have been isolated reports of using computed tomography (CT) cisternography scans for radiation planning for TGN.

CASE DESCRIPTION

A 75-year-old male with a permanent pacemaker who had refractory TGN in the V2 (maxillary) distribution of the trigeminal nerve underwent CT cisternography to prepare for MVD. CT angiography with Isovue 370 intravenous contrast injection and 0.625-mm axial images were obtained from the skull base across the posterior fossa. An intrathecal injection of Isovue 180 was performed at the L2/3 level. Imaging revealed the right SCA abutting the medial margin of the proximal right trigeminal nerve. In surgery (K.D.), a standard retrosigmoid suboccipital craniotomy was performed to access the cerebellopontine angle and separate the abutting SCA and trigeminal nerve. The patient had immediate pain relief.

CONCLUSIONS

MRI is the preferred method of evaluating for TGN because it offers excellent visualization of vasculature in relation to the trigeminal nerve without accompanying radiation exposure. However, for patients who have contraindications to MRI, CT cisternography is shown to also be an effective method for visualizing the trigeminal root entry zone and nearby vasculature in preparation for MVD of the trigeminal nerve.

Orofacial pain syndromes: evaluation and management

Patients will often visit their primary medical practitioner with orofacial pain complaints. Hence, it is important to recognize and have an understanding of these conditions to properly evaluate and potentially manage these disorders. If the practitioner is uncertain or uncomfortable with these conditions, then patient referral to a knowledgeable health care practitioner should be considered for further evaluation and management. In this article, the evaluation and management of various neuropathic, neurovascular, and vascular pains are discussed.