Walter Grand

Olfaction preservation in anterior cranial base approaches: an anatomic study.

OBJECTIVE To study the anatomic basis for olfaction-sparing anterior cranial base approaches. METHODS The medial anterior skull base containing the olfactory unit and delimited by the inner table of the frontal sinus, the lesser wing of the sphenoid bone, and the medial orbital walls was removed from six cadaveric specimens. Histological methods were used to investigate the location, distribution, and depth of penetration of olfactory nerves. Hematoxylin and eosin and Gomori trichrome staining were used to visualize landmarks and architecture. S-100 neurofilament protein immunostaining was used to identify nerve fascicles and axons. In three cadaveric head specimens, olfaction-sparing craniofacial approaches were performed and the excised olfactory units were evaluated histologically. RESULTS Bundles of olfactory nerves were identified primarily in the nasal septum; relatively fewer bundles could be identified in the middle turbinate. Olfactory nerve endings were identified up to 20 mm below the cribriform plate (range, 7–20 mm). The superior and middle nasal meatus were most innervated; olfactory innervation was virtually absent in the inferior nasal meatus. Histological evaluation of the olfactory unit elevated during olfaction-sparing techniques routinely revealed transection of olfactory nerves that exited the skull base. CONCLUSION In olfaction-sparing anterior cranial base approaches, the olfactory nerves are inevitably transected. The clinical significance of olfactory nerve transection for postoperative functional recovery of olfaction remains to be analyzed.

Endoscopic cauterization of a symptomatic choroid plexus cyst at the foramen of Monro: case report.

OBJECTIVE Choroid plexus cysts are common in the developing fetus, and although often persisting into adulthood, they rarely represent the underlying cause of symptomatic unilateral ventriculomegaly. The case presented here highlights both the diagnostic obscurity and endoscopic management of a choroid plexus cyst in a symptomatic patient. CLINICAL PRESENTATION The patient is a 47-year-old white woman who presented with acute exacerbation of debilitating, diffuse, and postural headache, nausea, vomiting, early papilledema, and short-term memory loss. Cranial magnetic resonance imaging revealed an intraventricular mass obstructing the foramen of Monro on the left with ventriculomegaly. Cranial computed tomographic imaging demonstrated unilateral ventricular enlargement. INTERVENTION During stereotactic endoscopic exploration, a choroid plexus cyst was evident at the foramen of Monro. Endoscopic cauterization of the cyst resulted in a decrease in the size of the left lateral ventricle, with complete relief of the patients headaches and resolution of her memory loss. She remained headache free at the time of a 3-year follow-up evaluation after surgery. CONCLUSION Choroid plexus cysts remain a diagnostic challenge; their presence should be sought out in the face of ventricular asymmetry and symptomatic hydrocephalus. Endoscopic ablation offers a minimally invasive treatment for the management of these lesions.

Enlarged thalamostriate vein causing unilateral Monro foramen obstruction: Case report

Causes of unilateral hydrocephalus resulting from an obstruction at the Monro foramen include foraminal atresia, tumors, gliosis, contralateral shunting, and infectious and inflammatory conditions. However, few reports in the literature cite vascular lesions as the cause of the obstruction. To their knowledge, the authors present the first report of unilateral hydrocephalus occurring due to an abnormally enlarged thalamostriate vein independent of an arteriovenous malformation or developmental venous angioma. The condition was treated successfully by endoscopic septum pellucidum fenestration. A 28-year-old man was referred for evaluation due to a 10-year history of chronic headaches that worsened in severity over the past year. A CT scan of the head revealed unilateral right ventricular dilation. Cranial MR imaging with and without contrast administration showed a dilated right thalamostriate-internal vein complex without any evidence of associated arteriovenous malformation or venous angioma. Endoscopic exploration of the right lateral ventricle showed an enlarged subependymal thalamostriate vein obstructing the Monro foramen. An endoscopic fenestration of the septum pellucidum was performed, resulting in alleviation of the patients symptoms. Abnormally enlarged venous structures may cause obstructive unilateral hydrocephalus and can be a rare cause of chronic, intermittent headaches in adults. Endoscopic fenestration of the septum pellucidum is an effective treatment.