Leveraging high-resolution 7-tesla MRI to derive quantitative metrics for the trigeminal nerve and subnuclei of limbic structures in trigeminal neuralgia

Abstract

Background Trigeminal Neuralgia (TN) is a chronic neurological disease that is strongly associated with neurovascular compression (NVC) of the trigeminal nerve near its root entry zone. The trigeminal nerve at the site of NVC has been extensively studied but limbic structures that are potentially involved in TN have not been adequately characterized. Specifically, the hippocampus is a stress-sensitive region which may be structurally impacted by chronic TN pain. As the center of the emotion-related network, the amygdala is closely related to stress regulation and may be associated with TN pain as well. The thalamus, which is involved in the trigeminal sensory pathway and nociception, may play a role in pain processing of TN. The objective of this study was to assess structural alterations in the trigeminal nerve and subregions of the hippocampus, amygdala, and thalamus in TN patients using ultra-high field MRI and examine quantitative differences in these structures compared with healthy controls. Methods Thirteen TN patients and 13 matched controls were scanned at 7-Tesla MRI with high resolution, T1-weighted imaging. Nerve cross sectional area (CSA) was measured and an automated algorithm was used to segment hippocampal, amygdaloid, and thalamic subregions. Nerve CSA and limbic structure subnuclei volumes were compared between TN patients and controls. Results CSA of the posterior cisternal nerve on the symptomatic side was smaller in patients (3.75 mm2) compared with side-matched controls (5.77 mm2, p = 0.006). In TN patients, basal subnucleus amygdala volume (0.347 mm3) was reduced on the symptomatic side compared with controls (0.401 mm3, p = 0.025) and the paralaminar subnucleus volume (0.04 mm3) was also reduced on the symptomatic side compared with controls (0.05 mm3, p = 0.009). The central lateral thalamic subnucleus was larger in TN patients on both the symptomatic side (0.033 mm3) and asymptomatic side (0.035 mm3), compared with the corresponding sides in controls (0.025 mm3 on both sides, p = 0.048 and p = 0.003 respectively). The inferior and lateral pulvinar thalamic subnuclei were both reduced in TN patients on the symptomatic side (0.2 mm3 and 0.17 mm3 respectively) compared to controls (0.23 mm3, p = 0.04 and 0.18 mm3, p = 0.04 respectively). No significant findings were found in the hippocampal subfields analyzed. Conclusions These findings, generated through a highly sensitive 7 T MRI protocol, provide compelling support for the theory that TN neurobiology is a complex amalgamation of local structural changes within the trigeminal nerve and structural alterations in subnuclei of limbic structures directly and indirectly involved in nociception and pain processing.

Risk Factors for Unilateral Trigeminal Neuralgia Based on Machine Learning

“…What are the differences in the structure of the cisternal segment of the trigeminal nerve? Alper et al (29) found that the cross-sectional area (CSA) of the cisternal segment of the trigeminal nerve was smaller in patients with TN compared with healthy controls (HC). It was speculated that CSA was a risk factor for TN, but the aforementioned study failed to clarify whether NVC occurred in HC.…”

Rich-club reorganization and related network disruptions are associated with the symptoms and severity in classic trigeminal neuralgia patients

“…In the present study, one of the hubs in the feeder was the thalamus, a critical relay and integration center connected with the higher-order cortex ( Antón-Bolaños et al, 2018 , Kumar et al, 2017 ). The thalamus is directly involved in the trigeminal sensory pathway ( Alper et al, 2021 ) and forms the medial pain system together with the PFC and limbic system (exactly the lPFC in the present study). As proposed, the medial system transmits slow dull pain information through the spinal reticular thalamic tract and the medial spinothalamic tract ( Peyron et al, 2000 ), and it is linked to emotional and cognitive aspects of pain ( Petrovic and Ingvar, 2002 ).…”

Рефрактерна Атипова Тригемінальна Невралгія, Асоційована З Реактивованою Герпесвірусною Інфекцією: Патогенетичний Зв’язок І Ефективність Комбінованого Противірусного Лікування

“…C. Rusbridge у відповідному систематичному огляді вказує, що порушення центральної регуляції болю при ураженні кортиколімбічної системи ЦНС (префрональної кори, гіпокампів, мигдалеподібних тіл) є одним із типових механізмів формування рефрактерних больових синдромів [42]. J. Alper зі співавт., використовуючи МР-томографи з величиною магнітної індукції котушки в 7 Тл, показали прогресуюче зменшення об'єму мигдалеподібних тіл у пацієнтів з рефрактерними тригемінальними невралгіями -феномен, типовий для скроневого медіанного склерозу у людей [4]. W. Liu зі співавт.…”