Prognostic value of olfactory nerve damage measured with thallium-based olfactory imaging in patients with idiopathic olfactory dysfunction.

Idiopathic olfactory disorder is resistant to treatment, and the recovery time is long. This study investigated the prognostic value of the migration of nasally administered thallium-201 to the olfactory bulb (thallium migration to the OB), a measure of olfactory nerve damage, in patients with idiopathic olfactory disorders. Twenty-four patients with idiopathic olfactory disorders were enrolled in the study (7 women and 17 men; aged 23-73 years). We retrospectively analyzed potential prognostic markers in subjects who underwent thallium-based olfactory imaging with the nasal administration of thallium-201 before conventional treatment with the Japanese herbal medicine tokishakuyakusan and compared those data with the prognosis. Log-rank tests were performed to assess the relationship between thallium migration to the OB (<4.6% [low] vs. ≥4.6% [high]; data dichotomized at the optimal cutoff value) and the duration until recovery of the odor recognition threshold determined by a standard olfactory function test (T&T olfactometry) after the treatment. Upon statistical analysis, we found that high thallium migration to the OB was significantly correlated with better prognosis in patients. Our results suggest that patients with intact olfactory nerve fibers could be selected using thallium-based imaging for the long-term follow-up of olfactory dysfunction.

An enigmatic clinical entity: A new case of olfactory schwannoma.

Olfactory schwannomas, also described as subfrontal or olfactory groove schwannomas, are very rare tumors, whose pathogenesis is still largely debated. We report a case of olfactory schwannoma in a 39-year-old woman who presented with anosmia and headache. The clinical examination did not show lesions in the nose-frontal region and there was no history of neurofibromatosis. Head MRI and CT scan revealed a lobulated extra-axial mass localized in the right anterior cranial fossa that elevated the ipsilateral frontal pole. Bilateral frontal craniotomy demonstrated a tumor strictly attached to the right portion of the cribriform plate that surrounded the right olfactory tract, not clearly identifiable. The immunohistochemical analysis suggested the diagnosis of typical schwannoma. The patient was discharged without any neurological deficit and a four-month postoperative MRI scan of the brain showed no residual or recurrent tumor.

Olfactory schwannoma: a report of two cases and literature review.

Intracranial schwannoma is a kind of benign intracranial tumors, derived from neuron myelin sheath, growing slowly and curable. Olfactory schwannoma is an exceedingly rare kind of schwannoma, whose origin is still uncovered. Although several theories have been put up for pathogenesis of olfactory schwannoma, till now, none of these hypotheses has been widely accepted and acknowledged officially. Up to date, only 46 cases of olfactory schwannoma were reported across numerous institutes worldwide. Here we gathered two cases from Department of Neurosurgery in Beijing Tiantan Hospital across two years collection.

Olfactory colloid cyst: case report and review of extraventricular colloid cyst literature.

OBJECTIVE: A rare case of an extraventricular colloid cyst located in the olfactory groove extending downward into the ethmoid sinus is presented. This is the second reported case in the world literature. METHODS: A 56-year-old-woman presented with a lesion that was causing hyposmia and cerebrospinal fluid rhinorrhea. The lesion was an extraventricular colloid cyst displacing the left olfactory nerve downward and eroding into the left ethmoid sinus. RESULTS: The lesion was excised, and the anterior skull base was reconstructed successfully via a unilateral subfrontal approach. CONCLUSIONS: There were no complications, and the patient made a full recovery, with resolution of the cerebrospinal fluid rhinorrhea.

The olfactory system.

Any dysfunction in olfaction requires a radiological exploration comprising the nasal cavity, the anterior base of the skull, in particular the frontal and temporal lobes. MRI is the reference examination, due to the frontal plane and the T1, T2 volume maps. In the child, aplasia of the olfactory bulbs falls within a polymalformation (CHARGE) or endocrine (Kallman) context. In the adult, rhino sinus disease and meningiomas are the most common etiologies. Frontal or temporal impairment: tumoral or vascular and neurodegenerative disorders (Parkinson's disease) may accompany a loss of olfaction.

[Olfactory ensheathing cell tumour: case report and literature review]. / Tumor de las células envolventes del olfatorio: caso clínico y revisión de la literatura.

Olfactory ensheathing cells are glial cells located in the olfactory bulb and nerve. Microscopically, both olfactory ensheathing cells and Schwann cells have similar morphological and immunohistochemical features. However, olfactory ensheathing cells are negative for Leu-7(CD-57), whereas Schwann cells are positive. We present the case of a 49 year-old male with a history of visual impairment and hyposmia. Radiological CT and MRI studies showed a subfrontal cystic extra-axial mass, which eroded the right cribriform plate, with heterogeneous contrast enhancement. Total excision of the tumour was performed by bifrontal craniotomy. Histological examination initially suggested a schwannoma, with immunohistochemical staining being positive for S-100 protein and negative for epithelial membrane antigen (EMA). However, the tumour was negative for Leu-7. Accordingly, the final diagnosis was olfactory ensheathing cell tumour. Herein, we describe the sixth case of intracranial olfactory ensheathing cell tumour and stress the important role of immunohistochemical techniques in obtaining a definitive diagnosis.

Tumor fibroso solitario meníngeo del surco olfatorio / No disponible

No disponible

Cystic olfactory schwannoma of the anterior cranial base.

Olfactory groove schwannomas are extremely uncommon and less than 30 cases are reported in the literature. We report a 21-year-old developmentally-retarded boy who experienced severe headache and aggressive behaviour for 5 months. Imaging showed a cystic mass in the subfrontal region, which was removed by craniotomy. The lesion had a vascular supply from the anterior ethmoidal arteries and it was noted to be attached to the right olfactory nerve. It was removed completely and histology showed it to be a schwannoma. Olfactory groove schwannomas are rare lesions and should be differentiated from meningiomas, neuroblastomas and dural-based metastatic lesions of the anterior cranial base.

Pathology of the olfactory nerve.

The olfactory system and especially the olfactory bulb (OB) as the first relay in the olfactory system represent highly plastic structures. For example, OB volume partly reflects the degree of afferent neural activity. Research indicates that smell deficits leading to a reduced sensory input result in structural changes at the level of the OB. Reduced OB volumes also may be considered characteristic of parosmia. Apart from discussing the clinical implications of these findings, the radiologic basics for assessment of olfactory-eloquent structures are addressed in detail.

Olfactory schwannoma.

We report a case of olfactory schwannoma with calcification. Intraoperative findings indicated that the tumour originated from the olfactory groove. Intraoperative findings of previous studies have not indicated a clear relationship between subfrontal schwannoma and the olfactory nerve, which seems strange, given the association between tumours and cranial nerves at other sites. We suggest this observation has not been reported because the growing olfactory schwannoma changes the local morphology, affecting the appearance of the olfactory nerve.

[Olfactory groove schwannoma: case report]. / Schwannoma da goteira olfatória: relato de caso.

Intracranial schwannoma not related to cranial nerves are unusual and rarely found in the subfrontal region. We report a case of olfactory groove schwannoma in a 27-year-old male, who presented with anosmia and headache initiated one year ago. At admission, bilateral papilledema was noted with absense of motor deficits or cranial nerves abnormalities. Cranial computed tomography (CT) revealed a bifrontal multicystic isodense enhancing mass lesion causing a frontal ventricular horn compression. Radiological features resembled that of a cystic olfactory groove meningioma. Decompressive bifrontal craniotomy was done. One month later, CT demonstrated a homogeneously contrast-enhancing mass in the olfactory groove region who extended into the left nasal cavity. Magnetic resonance imaging did not add more informations. A second surgical procedure was done through a nasoethmoidal approach with incomplete resection of the lesion. The complete tumor resection was only possible in a third surgery through another bifrontal approach. The hystopathological diagnosis of schwannoma was performed by conventional methods and confirmed by immunohistoquemical staining for S-100 protein. The rarity of this tumor and his clinical, radiological and histological aspects justify this publication.

Olfactory neuroepithelioma arising from the olfactory placode.

The patient was a 54-year-old man, who had lost his sense of smell 6 years previously and had started to become forgetful about 6 months prior to presenting at hospital. MRI admission showed a large multicystic tumor with Gd-DTPA enhancement extending from the anterior cranial fossa through the sphenoid sinus and into the nasal cavity. Histopathological examination revealed extensive proliferation of small round cells that were divided by connective tissue septae. The tumor cells occasionally formed tubular structures, although no basement membranes were present. On immunostaining, round tumor cells were positive for neuron-specific enolase, synaptophysin, and chromogranin A, while cells forming tubules were positive for AE 1 and CAM 5.2. Almost all of the tumor cells were positive for Ber-EP4, and some of the epithelioid cells surrounding the tubular structures were also positive for luteinizing hormone-releasing hormone (LH-RH). Electron microscopy demonstrated sporadic intercellular junctions, many microtubules in the tumor cell processes, and clear- and dense-cored vesicles in the cytoplasm. Based on the results, this case appears to be the first documented neuroepithelioma with Ber-EP4- and LH-RH-positive cells arising from the olfactory placode.