Katsumi Suematsu

Gamma knife surgery for Cushing's disease

BACKGROUND The efficacy of gamma knife surgery on Cushings disease is not well known to date. In most reported cases of Cushings disease treated with gamma knife, the area to be irradiated was determined with computed tomography or pneumoencephalography. We report two cases of recurrent pituitary-dependent Cushings disease treated with gamma knife using stereotactic magnetic resonance imaging (MRI). MATERIALS AND METHODS Recurrent microadenomas were visualized as hypointense areas using gadolinium-enhanced MRI after two transsphenoidal surgeries in both cases. The doses of irradiation given were 35 Gy and 20 Gy to the margin of the tumors, and less than 8 Gy and 21 Gy to the optic apparatus and cranial nerves in the cavernous sinus, respectively. RESULTS Both patients had clinical remission with normal serum cortisol and adrenocorticotrophic hormone levels, during 2-year follow-up after radiosurgery, without endocrinologic deficiency or neurologic deterioration. CONCLUSIONS Gamma knife surgery can be an alternative therapy for Cushings disease when pituitary adenomas are apart from the optic apparatus and can be visualized clearly by MRI, even if tumors are recurrent after microsurgery.

Quantification of regional cerebral blood flow and vascular reserve in childhood Moyamoya disease using [123I]IMP-ARG method

Both regional cerebral blood flow (rCBF) and regional vascular reserve (rVR) in ten childhood Moyamoya disease were quantified pre- and post-operatively by autoradiographic processing using single photon emission computed tomography (SPECT) and N-isopropyl-rho-iodoamphetamine (IMP) (IMP-ARG method) to estimate hemodynamic effectiveness of surgical revascularization. Before surgery, in two patients, rCBF was reduced in the whole territories and loss of rVR in the anterior circulation was observed; +4.3% in the anterior cerebral artery (ACA), -3.0% in the middle cerebral artery (MCA) and +17.5% in posterior cerebral artery (PCA) territories. After surgery, in eight patients without transient ischemic attack (TIA) episodes, rCBF at rest was maintained around subnormal level in the whole territories, and mean rVR was up to +11.9, +17.3 and +28.3% in ACA, MCA and PCA territories, respectively. However, rVR in the anterior circulation was significantly reduced in comparison with rVR in the posterior circulation. Quantification of both resting rCBF and rVR using IMP-ARG method could provide reliable information concerning on surgical indication and its effectiveness in childhood Moyamoya disease.

Transient ischemic attacks caused by unruptured intracranial aneurysm

A case is reported of a 56-year-old man in whom an unruptured aneurysm of the left middle cerebral artery was the source of emboli resulting in transient ischemic attacks (TIAs). The potential relationship between TIAs and an unruptured aneurysm is discussed, and the literature is reviewed.

Completely thrombosed giant aneurysm of the angular artery

An unusual case of a completely thrombosed giant aneurysm arising from the angular artery is reported. A 69-year-old women developed a subarachnoid hemorrhage with a large intracranial hematoma. Computed tomography scans and cerebral angiography could not detect the aneurysm. The rarity of aneurysms in this position is stressed and the difficulty of diagnosis in this case is discussed.

Effect of gamma knife irradiation on relaxation and contraction responses of the common carotid artery in the rat

SummaryThis report concerns a pilot study of the short- and long-term effects of gamma knife radiosurgery on vascular responses. The investigation was carried out on male Sprague-Dawley rats, and the relaxation and contraction responses of the right common carotid artery (CCA) were assessed following irradiation (100 Gy). The non-treated CCA of the same animals served as internal controls. Non-irradiated rats were used to control the effect of normal aging on vascular function. Isometric tension was determined on in vitro preparations of arterial rings. Acetylcholine-mediated, endothelium-dependent relaxation was impaired one month after radiosurgery, as was endothelium-independent relaxation induced by sodium nitroprusside, but the effect on the latter was minimal. The irradiated CCA was also impaired with respect to contraction responses induced by norepinephrine, endothelin-1 or phorbol dibutyrate. This impairment appeared to be biphasic, as it was evident one day after radiosurgery, followed by a partial recovery one week later, and again manifest after one month. At the light microscope level, the carotid arteries appeared to be well preserved throughout the experiment. However, obvious ultrastructural changes were noted in endothelial and smooth muscle cells of specimens obtained three months after radiosurgery. The present data indicate that high dose gamma knife radiosurgery affects the functions of both, the vascular endothelium and the vascular smooth muscles in an apparent time-dependent fashion. Because of its increasing application to patients, there is the need for studying the effects of gamma knife radiosurgery on cerebral arteries, since functional vascular changes may occur in the absence of obvious histological alterations. Our results on CCAs point to the feasibility of such experimental investigations.

Correlation of SPECT with Angiography in Early Ischemic Stroke

The hyperacute thrombolytic therapy for selected patients with embolic stroke may actually provide benefit rather than risk [1–9]. The patient selection in thrombolytic stroke therapy might depend on early diagnosis of severity of cerebral ischemia or reversibility in ischemic brain tissue. It has been known that not only the time from the onset of stroke but also the residual cerebral blood flow (CBF) appear to be crucial for survival of marginal hypoperfusion areas [10–12]. A critical level of residual CBF might indicate functional reversibility in ischemic brain tissues and could be restored by early efficient recanalization of the occluded vessels. Cerebral angiographic studies in the early phase of embolic stroke could show prompt development of collateral circulating, reflecting residual CBF, and the degree of reperfusion following thrombolytic therapy in relation to increased CBF. To investigate the role of cerebral angiography in acute embolic stroke, we studied the correlation of CBF using single photon emission computed tomography (SPECT) with angiographic findings in early ischemic stroke within 6 h from the stroke onset.

Effect of Urokinase Cisternal Irrigation on Decrease of Subarachnoid Clot and Cerebral Vasodilatory Capacity during Cerebral Vasospasm

Within 24~48 hours after start of urokinase cisternal irrigation, an extreme amount of hemoglobin derived from the subarachnoid clot was withdrawn. CT number of cerebral cisterns decreased immediately in cases of urokinase cisternal irrigation while the reduction of CT number was slower in cases with cisternal drainage. Cerebral vasodilatory capacity assessed by DIAMOX(R) activated 123IIMP SPECT during the first and second week after subarachnoid hemorrhage showed less limitation in cases with urokinase cisternal irrigation than with cisternal drainage. Angiographical and symptomatic vasospasm were also expressed less severely in cases of urokinase cisternal irrigation than with cisternal drainage, and subsequently, no low density area in CT due to ischemia from vasospasm appeared with urokinase cisternal irrigation. In conclusion, urokinase cisternal irrigation accelerated clearance of subarachnoid clots, followed by reduction of severity of vasospasm and cerebral ischemia.

Monitoring of somatosensory evoked potentials during extracranial revascularization

Intraoperative somatosensory evoked potentials (SEPs) were measured in 17 patients during 21 extracranial revascularization and related procedures. The operations included 13 carotid endarterectomies (CEAs), two cervical internal carotid ligations, one vertebral artery (VA) clipping, one VA-common carotid artery (CCA) transposition, and four temporary balloon occlusion tests (TBOTs). Three of the 13 CEAs (23%) showed reduced amplitude and delayed latency of primary cortical SEPs during clamping of the carotid artery, followed by their recovery after emplacement of the internal shunt. Flattening of SEPs during clamping of the CCA was observed in the case of VA-CCA transposition; however, SEPs returned to normal immediately after insertion of a balloon indwelling shunt into the CCA. One of the four TBOTs showed alteration of SEPs during balloon occlusion of the subclavian artery proximal to the origin of the VA. In the others, SEPs remained stable during the entire procedure. Only one transient intraoperative ischemic complication was encountered among the cases of CEA. It was detected through flattening of SEPs, which led to the discovery of an internal shunt obstruction. Carotid stump pressure was also measured in 12 CEAs and two TBOTs, and seven of these 14 had pressure less than or equal to 50 mmHg. Four of the seven had carotid stump pressure less than or equal to 30 mmHg, and three of these four also showed altered SEPs. SEPs remained stable if the collateral flow was sufficient during vascular occlusion and showed obvious alteration when the blood flow was reduced to below the threshold. The authors conclude that monitoring of SEPs during extracranial revascularization is very useful.