Insulin was injected directly into the dorsal hippocampus (DHPC) of rabbits, and changes in hepatic acetate metabolism were studied. The injection of 50 microU insulin into the DHPC decreased the rates of 14C transfer from 14C-1-acetate into glucose and ketone bodies, and increased 14C transfer into cholesterol ester, triglyceride, free cholesterol and free fatty acids. But after insulin injection into the DHPC of rabbits with lesions of dorsal fornix (DFX), hepatic acetate metabolism did not differ from that of control rabbits, which received saline injection into the same brain region. From these results it might be suggested that the DHPC are parts of insulin-sensitive brain regulator system in the hepatic acetate metabolism.
Schwannomas are the most common intradural extramedullary spinal tumors. However, they are usually solid tumors, and totally cystic changes are rare. Herein, we report a case of a 46-year-old male presenting with numbness of right limbs, right hemiplegia, and posterior neck pain for one year. MRI revealed a well-defined cystic long-segment, from C1 to C6, intradural extramedullary mass. The lesion showed hypointense on T1WI, hyperintense on T2WI, hyperintense on DWI, and it was marginally enhanced on the contrast image with Gd-DTPA. C1 laminectomy and hemi-laminectomy from C2 to C6 was performed for tumor resection. The tumor was found to be totally cystic and tensed with a jelly-like content. It was completely resected with the attachment of the C3 dorsal root. Histopathological examination confirmed it to be a schwannoma. The mechanism of cyst formation in schwannoma is considered as results of ischemic necrosis associated with tumor growth, or cystosis due to degeneration of Antoni-type B region. The long-segment, totally cystic intradural cervical schwannoma is rare, but it should be included in the differential diagnosis of a cystic mass in the spinal region. It can be difficult to distinguish cystic spinal schwannomas from other cystic lesions like arachnoid cyst, epidermoid cyst, and neurenteric cyst. Contrast enhanced MRI is useful by enhancing the margin of the tumor.
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