27 cases of cranioplasty with autogenous bone grafts stored in a deep-freezer and autoclaved before use are reported. The results of follow-up for an average period of one year were satisfactory from the standpoint of brain protection and cosmetic reconstruction. A small area of absorption of grafted bone was observed in two cases on the follow-up skull roentgenograms. No serious complications were seen except in one case, whose bone flap had to be removed due to an epidural abscess. Experiments revealed that deep-freezing and autoclaving had only minimal effects on bone structure, although osteocytes degenerated. Autogenous bone flap after deep-freezing is a useful material for cranioplasty but sterilization before use is indispensable. Autoclaving is a simple method for sterilization of the flap, available in any operating theatre. It does not increase the risk of postoperative complications such as infection or absorption.
We showed that normovolaemic induced hypertension therapy was effective in reducing ischaemic symptoms attributed to cerebral vasospasm in 41 patients after subarachnoid haemorrhage. By inducing hypertension to 25% to 50% above normal systolic arterial blood pressure, we observed that in 17 of 24 cases (71%) neurological deficits improved. In four cases of haemorrhagic infarction, the blood pressure rose to over 50% of systolic arterial pressure, and a low density area was confirmed on computerized tomography (CT) scan prior to vasospasm. Induced hypertension was therefore not considered when a low density area was revealed on CT scan. Restriction of fluid input is usually a factor in producing hypovolaemia after a neurosurgical operation. Intravascular volume expansion has been reported effective in reversing ischaemic deficits. However, according to Poiseuille's equation, increasing blood volume to a state of hypervolaemia can not enhance flow. The cerebral blood flow (CBF) was raised by increasing perfusion pressure, reducing viscosity, or increasing blood vessel diameter. Intravascular volume expansion elevates not only systemic arterial pressure, but also pulmonary artery wedge pressure over 18 mmHg and cardiac index over 2.2. Since pulmonary oedema and congestive heart failure may develop, one should monitor haemodynamic parameters with the Swan-Ganz catheter as a preventive measure. We emphasize that normovolaemic induced hypertension, maintaining haemodynamics subset 1 of the comparable haemodynamic subsets, is effective in raising perfusion pressure of CBF.
This approach is preferred on anatomical grounds for cases of unruptured small and medium sized ACoA aneurysms projecting anteriorly or posteriorly because the anterior communicating artery complex area can be fully visualized with minimal manipulation of the frontal lobes and anterior cerebral arteries.
The microsurgical anatomy of the arteries of the pituitary stalk and gland as viewed from above was studied in 50 adult cadaveric hemispheres using the operating microscope. There were three types of vessels to the pituitary from above: the superior hypophyseal artery originating from the internal carotid artery, the infundibular artery from the posterior communicating artery, and the prechiasmal artery from the ophthalmic artery. The superior hypophyseal artery originated from the medial to posterior aspect of the internal carotid artery. The average number of vessels of the superior hypophyseal artery was 2.2 per hemisphere, and the diameter was 0.25 mm on average. The majority (76%) of superior hypophyseal arteries arose from the proximal half of the segment between the origins of the ophthalmic and posterior communicating arteries of the internal carotid artery. The infundibular artery originated mainly from the medial side (69%) of the posterior communicating artery. Its diameter was 0.22 mm, and number 0.23 per hemisphere. The number of prechiasmal arteries was 0.06 per hemisphere. As a result, there were on average 2.5 vessels per hemisphere, totally 5 per brain, with the average diameter 0.25 mm, supplying the pituitary stalk and gland from above. The clinical application of these anatomical data to the diagnosis and treatment of suprasellar tumours and carotid-ophthalmic aneurysms is discussed.
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