Side-to-side Asymmetry in Trigeminal Neuralgia

The Epidemiology, Cause, and Prognosis of Painful Tic Convulsif Syndrome: An Individual Patient Data Analysis of 192 Cases

BACKGROUND

Characterized by the coexistence of trigeminal neuralgia and ipsilateral hemifacial spasm (HFS), painful tic convulsif (PTC) is a rare entity that has not yet been systematically studied.

OBJECTIVE

To systematically explore the epidemiology, cause, prognosis, and prognosis predictors of PTC.

METHODS

We searched PubMed, Web of Science, and the Cochrane Library for relevant studies published between establishment of the library and July 1, 2020. Information on demographics, causes, specific interventions, and intervention outcomes was extracted. We first performed descriptive analysis of demographics, causes, and surgical outcomes of PTC. Univariate and multivariate regression methods were used to explore potential prognosis predictors. Further, a 2-step meta-analysis method was used to validate the identified factors.

RESULTS

Overall, 57 reports including 192 cases with PTC were included in the analysis. The median age of patients with PTC is 54 years (range, 44-62 years), with more patients being female (P < 0.001), initiated as HFS (P = 0.005), and being affected with left side (P = 0.045). The vertebrobasilar artery contributes to >65% of the causes of single vascular compression for PTC. Anterior inferior cerebellar artery/posterior inferior cerebellar artery involvement (odds ratio, 4.050; 95% confidence interval, 1.091-15.031) and older age (P = 0.008) predict freedom from symptoms and recurrence after microvascular decompression, respectively.

CONCLUSIONS

PTC occurs more in middle-aged women between 40 and 60 years old, initiates as HFS, and affects the left side. Vertebrobasilar artery compression is the most common single cause of PTC. Microvascular decompression effectively treated PTC, with a cure rate >80%. Anterior inferior cerebellar artery/posterior inferior cerebellar artery involvement predicts successful surgery and older age predicts recurrence.

The Measurement of Various Anatomical Structures and Assessment of Morphometric Development of Fetal Skull Base

BACKGROUND

As the skull base has a complex anatomy, we underline the importance of anomalies for side asymmetry. It is useful to investigate relationship between anatomical structures for the surgical procedure orientations. Dural adherence, enlarged superior petrosal sinus, influence of neural crest cells, and cranial base ossification are among the factors in morphometric growth on skull base.

MATERIAL AND METHODS

Twenty-five fetuses of an estimated gestational age ranging from 17 to 34 weeks were studied in the Anatomy Laboratory of Mersin University Medical Faculty. Craniotomy was made to each fetus and brain hemispheres were dissected. We put plates, passing from the external points of lateral and anterior-posterior borders of fetus heads that are perpendicular to each other. An analytical calculation was formulated for the angle of foraminae to the root of zygoma by using different formulations depending on their posterior or anterior location to the root of zygoma. Statistical method was based on correlation analysis, simple regression, independent 2 group t tests, SPSS20.0, and MedCalc 11.5 (MedicReS, New York, NY).

RESULTS

Neither side dominance for the jugular foramen, nor the differences of foramen rotundum, spinosum, and ovale to anterior skull wall, root of zygoma, and to midline were found to be significant.

CONCLUSION

There is a debate on asymmetry of foramina of the skull base. No certain consensus about the initiation time and the causes of asymmetry in the past was documented. Studies are to be encouraged to further enlighten pre-postnatal factors affecting the fetal skull base morphometrism.

Abnormal trigeminal nerve microstructure and brain white matter in idiopathic trigeminal neuralgia

Idiopathic trigeminal neuralgia (TN) is classically associated with neurovascular compression (NVC) of the trigeminal nerve at the root entry zone (REZ), but NVC-induced structural alterations are not always apparent on conventional imaging. Previous studies report lower fractional anisotropy (FA) in the affected trigeminal nerves of TN patients using diffusion tensor imaging (DTI). However, it is not known if TN patients have trigeminal nerve abnormalities of mean, radial, or axial diffusivity (MD, RD, AD - metrics linked to neuroinflammation and edema) or brain white matter (WM) abnormalities. DTI scans in 18 right-sided TN patients and 18 healthy controls were retrospectively analyzed to extract FA, RD, AD, and MD from the trigeminal nerve REZ, and Tract-Based Spatial Statistics (TBSS) was used to assess brain WM. In patients, the affected trigeminal nerve had lower FA, and higher RD, AD, and MD was found bilaterally compared to controls. Group TBSS (P<0.05, corrected) showed patients had lower FA and increased RD, MD, and AD in brain WM connecting areas involved in the sensory and cognitive-affective dimensions of pain, attention, and motor functions, including the corpus callosum, cingulum, posterior corona radiata, and superior longitudinal fasciculus. These data indicate that TN patients have abnormal tissue microstructure in their affected trigeminal nerves, and as a possible consequence, WM microstructural alterations in the brain. These findings suggest that trigeminal nerve structural abnormalities occur in TN, even if not apparent on gross imaging. Furthermore, MD and RD findings suggest that neuroinflammation and edema may contribute to TN pathophysiology.