A sound that we hear in a natural setting allows us to identify the sound source and localize it in space. The two aspects can be disrupted independently as shown in a study of 15 patients with focal right-hemispheric lesions. Four patients were normal in sound recognition but severely impaired in sound localization, whereas three other patients had difficulties in recognizing sounds but localized them well. The lesions involved the inferior parietal and frontal cortices, and the superior temporal gyrus in patients with selective sound localization deficit; and the temporal pole and anterior part of the fusiform, inferior and middle temporal gyri in patients with selective recognition deficit. These results suggest separate cortical processing pathways for auditory recognition and localization.

The thermic effect of glucose was investigated in nine obese and six lean subjects in whom the same rate of glucose uptake was imposed. Continuous indirect calorimetry was performed for 240 mmn on the supine subject. After 45 min 20% glucose was infused (609 mg/min) for i95 min and normoglycemia was maintained by adjusting the insulin infusion tate. At 2 h, propranolol was infused (bolus 100 ttg/kg; 1 ;igfkg. mm) for the remaining 75 min.To maintain the same glucose uptake (0.624 g/min), it was necessary to infuse insulin at 3.0±0. in the lean and obese subjects, respectively. These results suggest that the defect in the thermic effect of glucose observed in obese subjects is due to their insulin resistance, which is responsible for a lower rate of glucose uptake and hence decreased rate of glucose storage, which is an energy-requiring process.

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The constant finding of hyperproteinorrhachia in all these patients suggests that a high CSF protein content may be the underlying cause of hydrocephalus through a speculative mechanism of decreased CSF resorption.

Introduction Few series compare endoscopic third ventriculostomies (ETV) and ventriculoperitoneal shunts (VPS). To avoid the complications after a shunt insertion, there is an increased tendency to perform a third ventriculostomy. We reviewed all pediatric patients operated in the French-speaking part of Switzerland for a newly diagnosed obstructive hydrocephalus since 1992 and compared the outcome of patients who benefited from ETV to the outcome of patients who benefited from VPS. There were 24 ETV and 31 VPS. Discussion At 5 years of follow-up, the failure rate of ETV was 26%, as compared to 42% for the VPS group. This trend is also found in the pediatric series published since 1990 (27 peer-reviewed articles analyzed). Conclusion In accordance to this trend, although a statistical difference cannot be assessed, we believe that ETV should be the procedure of choice in pediatric obstructive hydrocephalus.

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Six cases of cyst of the ligamentum flavum with compression of a lumbar nerve root are reported. All patients exhibited recurrent back pain and sciatica. Investigation included computed tomography, myelography, or both. The correct diagnosis was reached before operation in only half the patients. High-resolution computed tomography performed in the four last patients outlined the cystic lesion with its low-density center. Surgical excision was performed in all patients. Microscopic examination showed a dense fibrous cyst arising from the ligamentum flavum. The lumen contained myxoid or necrotic material, but no epithelial lining. Cysts of the ligamentum flavum must be considered in the differential diagnosis of causes of sciatica. A firm radiological diagnosis may, at present, still require myelography combined with high-resolution computed tomography. Differentiation from synovial or ganglion cysts of the spine is discussed.

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