Neuronal degeneration and regeneration induced by axotomy in the olfactory epithelium of Xenopus laevis.

The olfactory epithelium (OE) has the remarkable capability to constantly replace olfactory receptor neurons (ORNs) due to the presence of neural stem cells (NSCs). For this reason, the OE provides an excellent model to study neurogenesis and neuronal differentiation. In the present work, we induced neuronal degeneration in the OE of Xenopus laevis larvae by bilateral axotomy of the olfactory nerves. We found that axotomy induces specific- neuronal death through apoptosis between 24 and 48h post-injury. In concordance, there was a progressive decrease of the mature-ORN marker OMP until it was completely absent 72h post-injury. On the other hand, neurogenesis was evident 48h post-injury by an increase in the number of proliferating basal cells as well as NCAM-180- GAP-43+ immature neurons. Mature ORNs were replenished 21 days post-injury and the olfactory function was partially recovered, indicating that new ORNs were integrated into the olfactory bulb glomeruli. Throughout the regenerative process no changes in the expression pattern of the neurotrophin Brain Derivate Neurotrophic Factor were observed. Taken together, this work provides a sequential analysis of the neurodegenerative and subsequent regenerative processes that take place in the OE following axotomy. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1308-1320, 2017.

Olfactory preservation during anterior interhemispheric approach for anterior skull base lesions: technical note.

Anosmia is not a rare complication of surgeries that employ the anterior interhemispheric approach. Here, we present a fibrin-gelatin fixation method that provides reinforcement and moisture to help preserve the olfactory nerve when using the anterior interhemispheric approach and describe the results and outcomes of this technique. We analyze the outcomes with this technique in 45 patients who undergo surgery for aneurysms, brain tumors, or other pathologies via the anterior interhemispheric approach. Anosmia occurred in 4 patients (8.8%); it was transient in 2 (4.4%) and permanent in the remaining 2 (4.4%). Brain tumors clearly attached to the olfactory nerve were resected in the patients with permanent anosmia. We found a significant difference in the presence of anosmia between patients with or without lesions that were attaching the olfactory nerve (p = 0.011). Our results suggested that fibrin-gelatin fixation method can reduce the reported risk of anosmia. However, the possibility of olfactory nerve damage is relatively high when operating on brain tumors attaching olfactory nerve.

Lesões olfatórias pós-traumáticas / Post traumatic olfactory lesions

OBJETIVO: Documentar a incidência de lesões traumáticas do nervo olfatório, assim como a etiologia traumática; correlacionar as lesões do nervo olfatório com achados radiológicos (lesões cranianas e intracranianas) e estudar lesões múltiplas de nervos cranianos. MÉTODOS: Vinte e quatro pacientes admitidos no Serviço de Emergência da Santa Casa de Misericórdia de São Paulo com lesão traumática do nervo olfatório foram incluídos. Os pacientes foram divididos em três grupos, de acordo com o escore da escala de coma de Glasgow (ECG): trauma leve (ECG de 13 a 15), moderado (ECG de 9 a 12) e grave (ECG de 3 a 8), assim como em diferentes graus de lesão do olfatório, como hiposmia, anosmia e parosmia, distribuição quanto a gênero, presença de fraturas, lesões intracranianas, fístulas liquóricas e mecanismo de trauma. RESULTADOS: Dos 24 casos, 15 lesões ocorreram em conjunto com outros nervos cranianos e em nove casos houve lesão exclusiva do nervo olfatório. O atropelamento foi a causa mais comum de lesão do nervo olfatório de forma isolada, assim como nas lesões de múltiplos nervos. Hematomas extradurais foram as lesões intracranianas mais frequentes e a ausência de fraturas predominou nos indivíduos estudados. CONCLUSÃO: Neuropatia traumática do olfatório deve ser pesquisada na admissão do paciente (quando possível), sobretudo quando houver evidência de traumas frontais ou occipitais.

OBJECTIVE: To register the incidence of the traumatic lesions to the cranial nerves and its etiology; to correlate the lesions to the radiological ndings (cranial and intracranial) and study multiple cranial nerve lesions. METHODS: Fifty-four patients admitted to the Emergency Service of Santa Casa de Misericórdia de São Paulo Hospital have been studied and lesions to the different cranial nerves were described. All patients were submitted do radiographic exams, computed tomography, and, when necessary, magnetic resonance imaging. The patients were divided into 3 groups according to the Glasgow Coma Scale (GCS) in: mild trauma (GCS: 13 to 15), moderate (GCS: 9 to 12) and severe (GCS: 3 to 8). RESULTS: Posttraumatic single nerve lesion was more frequent seen on olfactory, facial and oculomotor nerves.Running over was the main cause of these lesions (single nerve and multiple nerves). Contusions and extradural hematomas were the most frequent intracranial lesions. CONCLUSION: Traumatic cranial neuropathy occurs frequently and must be searched on the patient admission, because it can surgical decompression may necessary, such as decompression of the optic or facial nerves.

Strength testing of the human olfactory nerve at the frontal skull base.

Olfactory dysfunction may influence the quality of life tremendously. This study investigated the strength of the human olfactory nerve at the frontal skull base using cadavers. A total of 180 olfactory nerves were examined in 90 human cadaveric heads. The cut edges of the olfactory nerves were pulled until they were pulled out from the skull base. In the first set of 30 cases, each right olfactory nerve was pulled 0° laterally and 0° upward, and each left olfactory nerve was pulled 0° laterally and 15° upward. In the second set of 30 cases, each right olfactory nerve was pulled 0° laterally and 15° upward, and each left olfactory nerve was pulled 15° laterally and 15° upward. In the third set of 30 cases, each right olfactory nerve was pulled 15° laterally and 15° upward, and each left olfactory nerve was pulled 30° laterally and 15° upward. The strength of the olfactory nerve was measured when pulled in each direction. There was no significant difference in the strength of the olfactory nerves when pulling them in the postero-upward direction between 0° and 15° upward. The strengths of the olfactory nerves when pulling them in the postero-lateral direction 0° and 15° laterally were 3.14±1.87 and 4.05±1.70 g (mean ± standard deviation [SD]), respectively; the difference was almost significant. The olfactory nerve could be pulled more laterally than posteriorly because the retraction force is absorbed by the lateral wall of the olfactory fossa.