Histopathological changes in tissues surrounding vagal nerve stimulation generators: A retrospective analysis of revision surgeries.

PURPOSE: Vagal nerve stimulation (VNS) is an effective treatment for patients with epilepsy, depression, and other neuropsychiatric conditions. Understanding the tissue changes associated with VNS devices is crucial for optimizing patient outcomes and device development. This study aimed to investigate the histopathological changes in the tissues surrounding the VNS generator and explore potential correlations with clinical factors and battery performance. METHODS: A total of 23 patients who underwent VNS generator revision surgery owing to battery depletion were included. Tissue samples from the areas surrounding the VNS generator were obtained and analyzed for histopathological changes. Demographic and device-related variables were also recorded. RESULTS: Capsule formation was observed in all patients. Acute inflammation were not detected in any case. Perivascular lymphocytic infiltration, foreign-body giant cell reaction (FBGCR), and calcification were observed in 8.7%, 26.1%, and 43.5% of patients, respectively. Crystalloid foreign body appearance was noted in 4 patients. The median output current of the generator was higher in patients with lymphocytic infiltration than in those without lymphocytic infiltration. The median off time was higher in patients with skin retraction than in those without skin retraction. Moreover, discomfort was associated with the presence of FBGCR. CONCLUSION: Our study provides insights into the tissue changes associated with the VNS generator, with capsule formation being a common response. Crystalloid foreign body appearance was not reported previously. Further research is needed to understand the relationship between these tissue changes and VNS device performance, including the potential impact on battery life. These findings may contribute to VNS therapy optimization and device development.

Monostotic fibrous dysplasia involving occipital bone: a case report and review of literature.

Fibrous dysplasia (FD) is a progressive systemic bone tumour of young and it can be seen on cranial bones. FD is divided into three types according to radiological features. The second most common subtype is polyostotic subtype. With this article, we aimed to review and present clinical features, radiological examination, differential diagnosis and treatment management of a case of solitary monostotic fibrous dysplasia of occipital bone. 15 years old female patient admitted to our hospital for a bump and in the back of his head that she noticed 1 month ago. Her physical and neurological examination was normal. On cranial CT examination we detected a bony defect. Her gadolinium enhanced cranial MRI revealed bony defect along with massive gadolinium enhancement in adjacent tissue. On histopathologic examination; PANCK, CD68, CD1a were found negative and CD45, S-100, Vimentine were found positive. Ki-67 was 4,8%. In conclusion, fibrous dysplasia is a progressive bone disease of the young patients. Despite its resemblance to a benign lesion by not being symptomatic it can progress and cause severe bony defects and skin lesions. Total surgical resection is necessary and sufficient for total treatment.