Yasuaki Nakao

Lateral supraorbital keyhole approach to clip unruptured anterior communicating artery aneurysms.

OBJECT Clipping of an anterior communicating artery (A-com A) aneurysm requires various working angles for safe manipulation and observation. The lateral supraorbital keyhole approach provides a more lateral subfrontal corridor to observe and clip an A-com A aneurysm than the standard Perneczky method. METHODS Preoperative planning was individualized in each patient based on three-dimensional computed tomography (3D-CT) angiography and 3D-CT osteotomy planning images. The procedure consisted of a 40-50 mm periorbital skin incision, partial dissection of the anterior portion of the temporal muscle, a 35 x 25 mm keyhole minicraniotomy from the supraorbital area to the sphenoid ridge, and opening of the carotid cistern and sylvian fissure in an antegrade fashion. Ten keyhole clipping procedures were performed in 10 patients with unruptured A-com A aneurysms. RESULTS No shaving of scalp hair, drain placement, or anticonvulsant medication were required. No patient suffered neurological deficits or abnormal findings on postoperative magnetic resonance imaging. Most patients were discharged on the 2nd to 3rd postoperative days except for one patient who suffered from meningitis. CONCLUSIONS The lateral supraorbital keyhole approach is a minimally invasive treatment option for relatively small and unruptured A-com A aneurysms.

Functional recovery of neuronal activity in rat whisker-barrel cortex sensory pathway from freezing injury after transplantation of adult bone marrow stromal cells

The effect of transplantation of adult bone marrow stromal cells (MSCs) into the freeze-lesioned left barrel field cortex in the rat was investigated by measurement of local cerebral glucose utilization (lCMRglc) in the anatomic structures of the whisker-to-barrel cortex sensory pathway. Bone marrow stromal cells or phosphate-buffered saline (PBS) were injected intracerebrally into the boundary zone 1 h after induction of the freezing cortical lesion. Three weeks after surgery, the 2-[14C]deoxyglucose method was used to measure lCMRglc during right whisker stimulation. The volume of the primary necrotic freezing lesion was significantly reduced (P<0.05), and secondary retrograde degeneration in the left ventral posteromedial (VPM) thalamic nucleus was diminished in the MSC-treated group. Local cerebral glucose utilization measurements showed that the freezing cortical lesion did not alter the metabolic responses to stimulation in the brain stem trigeminal nuclei, but eliminated the responses in the left VPM nucleus and periphery of the barrel cortex in the PBS-treated group. The left/right (stimulated/unstimulated) lCMRglc ratios were significantly improved in both the VPM nucleus and periphery of the barrel cortex in the MSC-treated group compared with the PBS-treated group (P<0.05). These results indicate that MSC transplantation in adults may stimulate metabolic and functional recovery in injured neuronal pathways.

Optimal cerebrospinal fluid magnesium ion concentration for vasodilatory effect and duration after intracisternal injection of magnesium sulfate solution in a canine subarachnoid hemorrhage model.

OBJECT The optimal CSF Mg(++) concentration for vasodilation of spastic cerebral arteries after subarachnoid hemorrhage (SAH) and its duration are unknown. The temporal profile of the vasodilatory effect and optimal CSF Mg(++) concentration after the intracisternal injection of MgSO(4) solution were investigated in an SAH model in canines. METHODS Cerebral vasospasm was induced by experimental SAH using a 2-hemorrhage model in 26 female beagles. On Day 7, 0.5 ml/kg of 15, 10, 5, or 0 mmol/L MgSO(4) in Ringer solution was injected into the cerebellomedullary cistern. Angiography was performed on Day 1 (before SAH) and before and 1, 3, and 6 hours after the intracisternal injection on Day 7 to measure arterial diameters of the basilar artery (BA), superior cerebellar artery (SCA), and vertebral artery (VA). Cerebrospinal fluid Mg(++) was also measured at the same time. RESULTS Arterial diameters of the BA, SCA, and VA were significantly decreased by vasospasm on Day 7. Arterial diameter ratios (ratio of arterial diameter after MgSO(4) injection to diameter before injection on Day 7) of the BA and SCA at 1 and 3 hours after and the VA at 1 hour after intracisternal injection of the MgSO(4) solution were positively correlated with the CSF Mg(++) concentration. All arterial diameter ratios, except 1 point of the SCA, exceeded 1 if the CSF Mg(++) concentration was > 3 mEq/L at 1 hour after injection. Animals with CSF Mg(++) concentrations > 3 mEq/L at 1 hour after injection (11 dogs) showed significantly increased arterial diameters of the BA at 1 and 3 hours after and of the SCA and VA at 1, 3, and 6 hours after injection, as compared with the diameters before injection. The CSF Mg(++) concentration significantly increased at 1 hour (3.73 ± 0.69 mEq/L, p < 0.01) and 3 hours (2.05 ± 0.35 mEq/L, p < 0.01) after the intracisternal injection as compared with the baseline value (1.41 ± 0.20 mEq/L). CONCLUSIONS The reversible effect of an intracisternal injection of MgSO(4) solution on the spastic artery requires CSF Mg(++) concentrations > 3 mEq/L. The vasodilatory effect continues for 3-6 hours after injection. These results suggest that the continuous infusion or intermittent intracisternal injection of MgSO(4) is needed to maintain the optimal CSF Mg(++) concentration and constantly ameliorate cerebral vasospasm.

Novel vasodilatory effect of intracisternal injection of magnesium sulfate solution on spastic cerebral arteries in the canine two-hemorrhage model of subarachnoid hemorrhage

OBJECT The extracellular Mg++ has a vasodilatory effect on the cerebral artery. The present study investigated the effect of intracisternal injection of MgSO4 solution on cerebral vasospasm in a canine model of subarachnoid hemorrhage (SAH). METHODS Subarachnoid hemorrhage was induced in 10 beagles using the two-hemorrhage model. Angiography of the vertebrobasilar artery was performed on Day 1 (baseline values before SAH) and on Day 7 (during cerebral vasospasm after induced SAH) before and after intracisternal injection of 0.5 ml/kg of 15 mmol/L MgSO4 solution into the cerebellomedullary cistern. RESULTS The cerebrospinal fluid Mg++ concentration was significantly increased to 3.15 +/- 1.14 mEq/L after intracisternal injection from the preinjection value (1.45 +/- 0.09 mEq/L; p < 0.01). The diameters of the basilar artery, vertebral artery, and superior cerebellar artery on Day 7 were significantly decreased to 58.0 +/- 10.9%, 71.0 +/- 10.1%, and 60.9 +/- 13.8%, respectively, of their baseline diameters on Day 1 (p < 0.01). After intracisternal injection of MgSO4, these diameters significantly increased to 73.8 +/- 14.3%, 83.0 +/- 14.8%, and 74.1 +/- 13.5%, respectively (p < 0.01). CONCLUSIONS Intracisternal injection of MgSO4 solution causes significant dilation of spastic cerebral arteries in the canine two-hemorrhage model of SAH.

Modification of three-dimensional prototype temporal bone model for training in skull-base surgery

Experience with dissection of the temporal bone is essential for training in skull-base surgery, but only a limited number of neurosurgical residents have the opportunity of cadaver dissection. A modification of a commercially available prototype three-dimensional (3D) temporal bone model is proposed to include artificial dura mater, venous sinuses, and cranial nerves for such surgical training. The base 3D temporal bone model incorporates the surface details and the inner ear structures and air cells. Model dural sinuses and dura mater made from silicone, cranial nerves made from rubber fibers, and internal carotid artery made from rubber tubes were added to the model. Posterior petrosectomy (transpetrosal approach) and transcondylar approach were performed on this model using a high-speed drill and ultrasonic bone curette under an operating microscope. The modified 3D temporal bone model provided good experience with the complicated 3D anatomy. The model could be dissected, and the dural sinuses and dura mater preserved by the eggshell peeling technique in almost the same way as real temporal bone. The modified 3D temporal bone model provides a good educational tool for training in skull-base surgery.

Surgical management for glossopharyngeal neuralgia associated with cardiac syncope: two case reports

Two patients with glossopharyngeal neuralgia associated with cardiac syncope were treated with temporary cardiac pacemakers for cardiac syncope and then microvascular decompression. The offending arteries were the posterior inferior cerebellar artery in one patient and the anterior inferior cerebellar artery in the other. The offending arteries were attached to the glossopharyngeal nerve and the vagal nerve at the root entry zones. After surgery, the patients were free from neuralgia and cardiac syncope did not occur after the pacemakers were extracted. Implantation of a temporary cardiac pacemaker in the perioperative period ensures safe microvascular decompression.

Intracranial pseudoaneurysm due to rupture of a saccular aneurysm mimicking a large partially thrombosed aneurysm ("ghost aneurysm"): radiological findings and therapeutic implications in two cases.

Intracranial pseudoaneurysm formation due to ruptured non-traumatic saccular aneurysm is extremely rare. We experienced two cases of large pseudoaneurysm formation due to rupture of a saccular aneurysm. The neuroradiological ghost-like appearance of the aneurysms led to misdiagnoses as large partially thrombosed aneurysm. Two cases of large intracranial pseudoaneurysm formation due to rupture of a saccular aneurysm occurred in a 77-year-old comatose woman with an aneurysm on the anterior wall of the internal carotid artery and a 73-year-old comatose woman with an anterior cerebral artery (azygos) aneurysm. Both patients suffered subarachnoid hemorrhage associated with intracerebral and intraventricular hematomas. Angiography showed peculiar “ghost-like” appearance of the aneurysm including delayed filling, changing shape, retention of the contrast material after the venous phase, and unclear location of neck. Neck clipping surgeries were performed, but were difficult because of the preoperative misdiagnosis as large partially thrombosed aneurysm. The entity of “ghost aneurysm” caused by rupture of a saccular aneurysm should be considered in the clinical diagnosis.

Efficacy of Low-Dose Tissue-Plasminogen Activator Intracisternal Administration for the Prevention of Cerebral Vasospasm After Subarachnoid Hemorrhage

BACKGROUND Vasospasm is one of the important factors associated with the functional prognosis after subarachnoid hemorrhage (SAH). Intracisternal administration of thrombolytic agents to dissolve subarachnoid clots may be responsible for bleeding complications. The efficacy and safety of cisternal irrigation therapy using low-dose tissue plasminogen activator were evaluated. METHODS Sixty patients with SAH were treated by surgical clipping, and randomly divided into three groups: 1) the control group (n = 20) treated only with baseline treatment; 2) the intermittent group (n = 20) received intermittent administration of clotlysis agent (tisokinase 960,000 IU); and 3) the continuous group (n = 20) received continuous irrigation using pH-adjusted lactate Ringers solution containing tisokinase (96 IU/mL) infused at 20 mL/hr for 48 hours. The clearance of subarachnoid clots was measured by laboratory examinations and postoperative computed tomography. Ischemia-related vasospasm was evaluated by neurological status and computed tomography. Neurological outcome was evaluated by the modified Rankin scale at 3 months after onset. RESULTS The subarachnoid clot was efficiently and significantly removed without major complication in the intermittent and continuous groups (P < 0.05). The incidence of ischemic lesion in the intermittent group was significantly lower than in the control group (P < 0.05). The intermittent group had significantly better neurological outcome than the control group (P < 0.05). CONCLUSIONS Cisternal irrigation therapy using low-dose tissue plasminogen activator is effective and safe. Intermittent injection is most effective and may decrease the risk of symptomatic vasospasm in patients with SAH.

Surgical Simulation of Extradural Anterior Clinoidectomy through the Trans-superior Orbital Fissure Approach Using a Dissectable Three-dimensional Skull Base Model with Artificial Cavernous Sinus.

Extradural anterior clinoidectomy via the trans-superior orbital fissure (SOF) approach can provide extensive exposure of the anterior clinoid process and safe drilling under direct view. This technique requires peeling of the dura propria of the temporal lobe from the lateral wall of the SOF. Therefore, cadaveric dissection is mandatory to acquire surgical technique. However, chances for cadaveric dissection are limited. We propose modification of our three-dimensional (3-D) skull base model made from surgically dissectable artificial bone with artificial cavernous sinus including multiple membranous layers and neurovascular structures to simulate extradural anterior clinoidectomy via the trans-SOF approach. The 3-D skull base model precisely reproduced the dura propria of the temporal lobe, periosteal bridge, and inner reticular layer in the cavernous sinus and SOF using silicone and varnish. The cranial nerves and blood vessels were made from rubber fibers and vinyl tube. Simulation of extradural anterior clinoidectomy via the trans-SOF approach could be performed on the model using a high-speed drill under the operating microscope. The steps of reconstruction of the skull base model and dissection promote clear understanding of the 3-D anatomy and techniques of extradural anterior clinoidectomy via the trans-SOF approach.

Development of artificial cranial base model with soft tissues for practical education: technical note.

OBJECTIVE Improved educational tools for anatomic understanding and surgical simulation of the cranial base are needed because of the limited opportunities for cadaver dissection. A 3-dimensional cranial base model with retractable artificial dura mater is essential to simulate the epidural cranial base approach. METHODS We developed our 3-dimensional cranial base model with artificial dura mater, venous sinuses, cavernous sinus, internal carotid artery, and cranial nerves, and the extradural temporopolar approach was simulated using this new model. INSTRUMENTATION This model can be dissected with a surgical drill because of the artificial bone material. The periosteal dura was reconstructed in the medial wall of the cavernous sinus, periorbita, and periosteal bridge in the superior orbital fissure with yellow silicone. The meningeal dura was made with brown silicone. The single-layer dura mater could be dissected from the bone surface and retracted with a surgical spatula. RESULTS Extradural drilling of the superior orbital fissure and opening of the optic canal were similar to actual surgery. Extradural anterior clinoidectomy was performed via the extradural space by retracting the artificial dura mater. The artificial dura propria of the lateral wall in the cavernous sinus was successfully peeled from the artificial cranial nerves to complete the extradural temporopolar approach. CONCLUSION The improved 3-dimensional cranial base model provides a useful educational tool for the anatomic understanding and surgical simulation of extradural cranial base surgery.