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Biomedical subjects

Samuel Tobias

Publications and source records attributed to Samuel Tobias.

6 recordsLinked to original sources
PubMed2006

Wilbrand's knee: does it exist?

OBJECTIVE: In 1904, Hermann Wilbrand reported that nasal ON fibers form a loop into the contralateral ON, subsequently referred to as Wilbrand's knee. He had further theorized that a lesion affecting Wilbrand's knee would develop a distinct visual field defect characterized by an ipsilateral central scotoma with a contralateral superotemporal visual field defect. We present clinical evidence that disputes the existence of Wilbrand's knee. METHODS: A retrospective analysis of 3 patients whose ONs were divided at the ON-chiasm junction is presented. Two patients had an ONS meningioma and the other patient had sarcoidosis of the ON. Resection of the lesion and the ON up to the nerve-chiasm junction was done to prevent the disease from extending into the OC and the contralateral ON. The patients had detailed neuro-ophthalmologic evaluations preoperatively and postoperatively. RESULTS: After the resection of the ON at the ON-chiasm junction in the 3 patients, junctional scotoma could not be detected by visual perimetry. CONCLUSION: No clinical perimetric evidence was found to support the existence of Wilbrand's knee in the anterior visual pathway.

Adult↗
PubMed2004

Surgical procedure "simplified retrosigmoid approach" for C-P angle lesions.

Previously, we reported surgical results of the simplified retrosigmoid approach for vestibular nerve sectioning in the cases with intractable vertigo. Here, we introduce in details surgical procedures of the simplified retrosigmoid (also called "subasterional" here for simplification) approach developed by one of the authors (J.H.L.). This approach is to operate cerebello-pontine (C-P) angle lesions through a small upper lateral window below the transverse-sigmoid junction. The retroauricular 4-5 cm skin incision, triangular craniectomy 2 cm in width, dural opening and closure, special considerations, and reconstruction of the skull defect were outlined. The bony landmarks for triangle craniectomy below asterion were described in detail. The C-P angle was appropriately approached for microvascular decompression, removal of C-P angle tumors, and vestibular nerve resection. This subasterional approach was characterized by short operation time of 1-3 h and less postoperative discomforts compared to the conventional retrosigmoid approach.

Cerebellar Diseases↗
PubMed2003

Management of surgical clinoidal meningiomas.

OBJECT: Clinoidal meningiomas remain a major neurosurgical challenge. Surgery-related outcome has been less than desirable in the past, and little attention has been directed toward improving visual deficits. The authors advocate a skull base technique for the removal of these difficult tumors and describe its advantages in terms of improving extent of resection and enhancing overall outcome, particularly visual function. METHODS: A retrospective analysis was performed on data obtained in 26 consecutive patients with clinoidal meningiomas (including one patient with hemangiopericytoma) who underwent resection between June 1995 and January 2003. In 24 cases the skull base procedure involved extradural anterior clinoidectomy, optic canal unroofing, and optic sheath opening; in two cases a standard pterional craniotomy was performed. Fourteen of the 26 patients suffered significant preoperative visual deficits. All patients underwent thorough pre- and postoperative ophthalmological evaluations. The follow-up period ranged from 3 to 91 months (mean 42.3 months). Total resection was achieved in 20 patients (77%), and the majority (76.9%) of patients with preoperative visual impairment experienced significant improvement. CONCLUSIONS: With the use of the skull base technique, total resection and excellent visual outcome may be achieved with minimal morbidity in most patients with clinoidal meningiomas.

Adolescent↗
PubMed2002

Necrotizing neurosarcoidosis of the cranial base resembling an en plaque sphenoid wing meningioma: case report.

OBJECTIVE AND IMPORTANCE: Necrotizing sarcoid granuloma (NSG) has been recognized as a histological variant of sarcoidosis. Two cases of neurosarcoidosis (NS) with NSG with concomitant systemic disease have been described previously. We present an unusual case of primary NS-NSG that resembled an en plaque cranial base meningioma. CLINICAL PRESENTATION: A 51-year-old man presented with a 3-month history of progressive left visual deterioration and proptosis. Brain magnetic resonance imaging demonstrated a large cranial base lesion occupying the left anterior clinoid process and sphenoid wing, extending to the left frontotemporal convexity. A second dura-based lesion was observed in the right parietal convexity. Both lesions enhanced homogeneously after administration of intravenous contrast medium. Magnetic resonance imaging characteristics were consistent with a typical clinoidal meningioma with an en plaque extension laterally. INTERVENTION: A left frontotemporal craniotomy with extradural removal of the anterior clinoid process was performed. When the dura was opened, a red fibrous mass was identified. Intraoperative histological analysis revealed the presence of necrotizing and noncaseating granulomas. Postoperatively, cerebrospinal fluid, erythrocyte sedimentation rate, C-reactive protein, and serum and cerebrospinal fluid angiotensin-converting enzyme values were normal. The search for acid-fast bacilli or fungi was negative. A diagnosis of primary NS-NSG was made. The patient began long-term high-dose corticosteroid therapy. One and a half years after surgery, his vision had improved significantly and the lesions were stable as revealed by magnetic resonance imaging. CONCLUSION: The first case of primary NS-NSG in the absence of systemic sarcoidosis is reported. NS should be included in the differential diagnosis of dura-based lesions resembling meningioma.

Diagnosis, Differential↗
PubMed2002

Rare Actinobacillus infection of the cavernous sinus causing painful ophthalmoplegia: case report.

OBJECTIVE AND IMPORTANCE: Actinobacillus actinomycetemcomitans is a gram-negative coccobacillus that is known to cause a wide array of clinical infections in debilitated patients, including periodontal disease, soft tissue abscess, pleural empyema, endocarditis, cerebral abscess, and meningitis. We report a rare A. actinomycetemcomitans cavernous sinus abscess that caused painful ophthalmoplegia in a healthy man. CLINICAL PRESENTATION: A 34-year-old man presented with a 3-month history of acute onset of left-sided retro-orbital pain that progressed to a complete left Cranial Nerve VI palsy and Cranial Nerve V1 and V2 hypesthesia. Magnetic resonance imaging revealed the presence of an enhancing lesion in the left cavernous sinus, which encased and narrowed the ipsilateral intracavernous segment of the internal carotid artery. Routine blood and cerebrospinal fluid analyses were normal. Tolosa-Hunt syndrome was suspected, and the patient was treated with high-dose corticosteroids. An open biopsy was performed after failed prolonged corticosteroid therapy. INTERVENTION: A left frontotemporal craniotomy and cavernous sinus exploration through an interdural approach were performed. A soft reddish mass was found in the cavernous sinus around Cranial Nerve V1 and V2. Multiple biopsies were obtained. Pathological analysis revealed a purulent infection containing multiple gram-negative coccobacilli. The patient's pain improved immediately, and cranial neuropathy resolved during the next several weeks. After cultures demonstrated growth of A. actinomycetemcomitans, a regimen of orally administered amoxicillin and metronidazole was initiated. Eight months after surgery, the patient was free of symptoms and a repeat magnetic resonance imaging scan was normal. CONCLUSION: We present a rare bacterial abscess of the cavernous sinus causing painful ophthalmoplegia. In patients who present with presumed Tolosa-Hunt syndrome and do not improve with prolonged high-dose corticosteroid therapy, an open biopsy is recommended to exclude a bacterial infection.

Actinobacillus Infections↗