Background: The aim of the study was to describe the origin, course, and termination of frontal aslant tract (FAT) in the Mexican population of neurosurgical referral centers. Methods: From January 2018 to May 2019, we analyzed 50 magnetic resonance imaging (MRI) studies in diffusion tensor imaging sequences of patients of the National Institute of Neurology and Neurosurgery “Manuel Velasco Suárez.” Five brains were fixed by the Klingler method and dissected in the neurosurgery laboratory of the Hospital Civil de Guadalajara to identify the origin, trajectory, and ending of the FAT. Results: FAT was identified in 100% of the MRI and brain dissections. The origin of the FAT was observed in 63% from the supplementary premotor area, 24% from the supplementary motor area, and 13% in both areas. Its ending was observed in the pars opercularis in 81%, pars triangularis in 9%, and in both pars opercularis and ventral premotor area in 10% in the magnetic resonance images, with a left side predominance. In the hemispheres dissections, the origin of FAT was identified in 60% from the supplementary premotor area, 20% from the supplementary motor area, and 20% in both areas. Its ending was observed in the pars opercularis in 80% and the pars triangularis in 20%. It was not identified as an individual fascicle connected with the contralateral FAT. Conclusion: In the Mexican population, FAT has a left predominance; it is originated more frequently in the supplementary premotor area, passes dorsal to the superior longitudinal fascicle II and the superior periinsular sulcus, and ends more commonly in the pars opercularis.

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Background: Myasthenia gravis (MG) is a post-synaptic autoimmune disease of the neuromuscular junction, whose cardinal manifestations are weakness and fatigue. Objective: The objective of the study was to report a cohort of patients with a diagnosis of MG in a West Mexican hospital and compare the clinical profile, diagnostic, and therapeutic approach and prognosis against a previously published cohort of the same hospital. Materials and methods: Consecutive patients included in two cohorts: the first one already published from 1999 to 2007 and the second one reported here from 2008 to 2018. Results: The most recent cohort included 39 patients, 23 women (59%), with an average age of 50 years, and superior to the previous cohort (43 years). Hypertension (39%) and diabetes (18%) were observed with a marked increase in the current cohort. The distribution in the Osserman staging was very similar. The positivity of acetylcholine receptor antibodies (ACRA) increased from 37% to 88%. In both cohorts, most patients received pyridostigmine and in two-thirds steroids. The previous cohort recorded 4% of patients treated with a steroid-sparing immunosuppressant, contrasting with 90% (azathioprine 85%, and mycophenolate 5%) of the current cohort. Thymectomy was a less frequent practice in 12%. Mortality showed a significant decrease from 16% to 0%. Conclusion: Differences were observed among the cohorts, highlighting in the most recent one a higher age, the appearance of chronic-degenerative diseases, greater positivity to ACRA, optimization of pharmacological management, less thymectomy, and no mortality. Replicas of this work in other hospital settings are pertinent.

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