Keiji Koshu

Measurement of regional blood flow using hydrogen gas generated by electrolysis.

Electrochemically generated hydrogen gas was used to measure local blood flow by Stosseck et al. The data obtained by their method, however, did not correlate well with those obtained by hydrogen inhalation. We have modified the equation proposed by Stosseck, prolonging the stimulus duration in order to increase the amount of hydrogen generated. In dog white matter the resulting clearance curves were formed to be monoexponential both in the living animal as well as after circulatory arrest when all the clearance is by diffusion away from the electrode. The values calculated by our equation correlated well with those obtained by hydrogen inhalation.

How to treat incidental cerebral aneurysms : a review of 139 consecutive cases

BACKGROUND Together with current advances in neuroimaging techniques, the chance of incidental discovery of unruptured cerebral aneurysms has increased and the selection of their appropriate management remains controversial. To provide current data about management results of patients with incidental cerebral aneurysms, we have made a retrospective review of 139 consecutive patients treated either by surgical or conservative means. METHODS The surgical indication for each patient was decided, carefully considering several factors respectively, including the surgical difficulty, aneurysm size, patients age, and medical condition. RESULTS Forty-nine patients were managed conservatively. Eight (16%) of those conservatively managed patients had intracranial hemorrhage due to aneurysm rupture during the follow-up period (mean, 4.3 years). Seven of these eight patients died from a fatal subarachnoid hemorrhage (SAH). The follow-up data showed that the mean size of aneurysms with late hemorrhage was significantly larger than that of aneurysms without subsequent rupture. It was also confirmed that none of the 26 tiny aneurysms smaller than 4 mm in diameter had ruptured. Ninety patients harboring 119 incidental aneurysms less than 25 mm in diameter underwent surgery. There was no surgical mortality or morbidity in this series. CONCLUSIONS These excellent surgical results were presumably achieved due to the strict patient selection. In respect to the size of aneurysms, it seems to be justified to recommend surgery for patients with aneurysms larger than 5 mm in diameter.

Combined Endovascular and Neurosurgical Approach for Paraclinoid Internal Carotid Artery Aneurysms

The authors review the surgical management of nine complex paraclinoid aneurysms treated with the endovascular balloon catheter technique. With the patient under general anesthesia, the balloon catheter was guided into the feeding artery of the aneurysm by the Seldinger technique. After the aneurysm was exposed, the balloon was inflated temporarily to prevent premature rupture and to facilitate the dissection of the aneurysm. For the larger paraclinoid aneurysm, the double-lumen catheter was introduced into the cervical internal carotid artery (ICA). After temporarily trapping the aneurysm by balloon occlusion of the cervical ICA and clipping the intracranial ICA distal to the aneurysm, retrograde aspiration was performed to collapse the aneurysm. The complete collapse of the large aneurysm by this technique allows an easier dissection of the aneurysm and a safer application of suitable clips. Such a retrograde suction decompression method was used in six large aneurysms. Intraoperative digital subtraction angiography was performed in all cases after the aneurysmal clipping; in three aneurysms, repositioning the clip was required. Only one case of embolic complication was related to the vessel catheterization in this series, which was discovered during the operation. An embolectomy was performed immediately, and there were no postoperative sequelae. We conclude that the combined endovascular and neurosurgical approach, particularly for the large ICA aneurysms, which are difficult to control proximally, can be a useful method of treatment. To prevent complications related to thrombus formation, further refinement in the balloon catheter itself is still needed.

Prevention of vasospasm by clot removal and intrathecal bolus injection of tissue-type plasminogen activator: preliminary report.

In this study, we evaluated the efficacy of postoperative intrathecal injections of tissue-type plasminogen activator (tPA) in preventing cerebral vasospasm in cases with a diffuse severe subarachnoid hemorrhage. All 10 cases were graded Group 3 according to the classification of Fisher and associates, and the CT number (Hounsfield number) of the subarachnoid clot was over 75. After clipping the aneurysm and removing the clot, three cisternal drainage catheters were inserted into both sylvian cisterns and the prepontine cistern, and continuous ventricular drainage was performed routinely. Postoperatively, tPA (0.5 mg/2.5 ml) was infused as a bolus into both basal cisterns and the lateral ventricle twice daily for about 6 days. Angiography and cerebral blood flow studies using single photon emission computed tomography were performed on Day 4 or 5 and between Days 7 and 10 after onset of the hemorrhage. To date, there have been no cases that have shown angiographic vasospasm or delayed ischemic neurological deficits. This preliminary study indicates that the intrathecal bolus injection of tPA produces a marked effect on vasospasm.

Anterior cervical fixation with the titanium locking screw-plate: A preliminary report

Anterior fixation of cervical spine with screw-plates is gaining in popularity in the management of anterior cervical spine instability. We report on our initial experience with anterior cervical fixation using the titanium locking screw-plate (TLSP). Twelve cases, including cervical trauma, cervical spondylosis, and ossification of the posterior longitudinal ligament (OPLL), underwent multilevel corpectomies or spondylectomies with iliac bone or hydroxylapatite grafting combined with the TLSP system. All 12 patients fused or stabilized with improvement of their neurologic symptoms at a mean follow-up period of 13 months. There were no complications relating to this plating system. Three illustrative cases are presented. Different from previous anterior cervical planting systems such as the Caspar plate, the TLSP system does not gain purchase on the posterior vertebral cortex. It thus reduces possible spinal cord injury during screw placement. The TLSP with interbody fusion may provide reliable stabilization of the cervical spine in a safe and effective manner.

Spinous process-splitting laminoplasty with an extended foraminotomy for cervical myelopathy.

We present the surgical results of a laminoplasty with an extended foraminotomy for cervical myelopathy. We chose spinous process-splitting laminoplasty, because it gave us the opportunity to perform bilateral foraminotomies through the same exposure. An extended foraminotomy means that root decompression is performed as far laterally as possible, using the surgical microscope. We performed this method in 18 patients and experienced favorable clinical results. Neuroradiological evaluations revealed good decompression of the spinal cord postoperatively. Although the operation time needed was longer compared with the original method, the average blood loss was 430 ml and blood transfusion was necessary in five patients. This method can be considered when cervical myelopathy is treated by a posterior approach.

Cine-mode magnetic resonance imaging of a thoracic intradural arachnoid cyst: Case report

We report the appearance of a thoracic intradural arachnoid cyst on cine-mode magnetic resonance imaging (MRI). Based on the operative findings, cine-mode MRI was more sensitive for identifying the intradural location of arachnoid cysts than was conventional MRI. The value of cine-mode MRI in diagnosing this rare entity is discussed.

Transoral Decompression Evaluated by Cine-Mode Magnetic Resonance Imaging: A Case of Basilar Impression Accompanied by Chiari Malformation

Cine-mode magnetic resonance imaging provides simultaneous images of cerebrospinal fluid flow dynamics. A patient with a basilar impression accompanied by a Chiari malformation and von Recklinghausens disease who underwent transoral decompression is reported. Preoperative cine-mode magnetic resonance imaging visualized an associated obstruction of cerebrospinal fluid pulsatile flow at the level of the foramen magnum. Tonsilar herniation (Chiari I malformation) and hydrocephalus were also present. Postoperatively, the obstruction of cerebrospinal fluid flow was resolved concomitant with the correction of the cervicomedullary angulation. On the basis of observations made by magnetic resonance imaging, the surgical treatment of basilar impression accompanied by Chiari malformation is briefly discussed.

Quantitative analysis of cerebrospinal fluid flow in patients with cervical spondylosis using cine phase-contrast magnetic resonance imaging.

OBJECTIVE To investigate changes in the cerebrospinal fluid flow in patients with cervical spondylosis using cine phase-contrast magnetic resonance (MR) imaging. METHODS The participants included 44 healthy volunteers, 11 asymptomatic patients with evidence of degenerative changes of the cervical spine revealed by MR imaging but no neurological symptoms referable to those abnormalities, and 23 symptomatic patients with myelopathy who underwent surgery. Cervical spondylotic myelopathy was evaluated using the Japanese Orthopedic Association scores, and the percentage reduction of the transverse cord area at the level of maximum cord compression was measured on T1-weighted magnetic resonance images. A cine phase-contrast MR pulse sequence with peripheral gating was used to measure the cerebrospinal fluid flow direction and velocity in the ventral subarachnoid spaces at the C1 and T1 levels. RESULTS The velocity waveforms produced by plotting flow velocity at 16 intervals during one cardiac cycle significantly differed among the healthy volunteers, asymptomatic patients, and preoperative symptomatic patients. However, velocity waveforms did not differ between the healthy volunteers and the postoperative patients at the C1 level. Decreases of flow velocity were significantly correlated with the severity of myelopathy and the percentage reduction of cord area. Patients with severe myelopathy (Japanese Orthopedic Association score of 0-9 points) or greater than 30% reduction of cord area showed significantly decreased flow velocity compared with those with mild myelopathy (Japanese Orthopedic Association score of 10-17 points) or less than 30% reduction of cord area. Changes in flow velocity were not correlated with multiplicity of the lesion or the level of maximum cord compression. Postoperative improvement of flow velocity was not correlated with neurological recovery. CONCLUSION Cine phase-contrast MR imaging allows quantitative and noninvasive assessment of changes in cerebrospinal fluid flow in patients with cervical spondylosis.

The protective effect of mannitol and perfluorochemicals on hemorrhagic infarction: An experimental study

Abstract Using the thalamic infarction model in the dog, the protective effect of mannitol and/or artificial blood (perfluorochemicals) on hemorrhagic infarction was investigated. In mannitol-treated animals some protective effect was found, especially in cases in which mannitol was administered within 60 minutes following occlusion. Hemorrhagic infarction was not suppressed in any of the perfluorochemical-treated animals, but there was no hemorrhagic infarction in any of the animals treated with both mannitol and perfluorochemicals. The present results are thought to indicate that these drugs administered together are effective in the treatment of hemorrhagic cerebral infarction.