Anatomical variations of the ten triangles around the cavernous sinus.

The dimensions of the 10 triangles around the cavernous sinus were measured to define the anatomical characteristics of the triangles and to compare their consistency in shape and area. Twelve tissue blocks containing the bilateral cavernous sinuses and medial two-thirds of the middle cranial fossae were obtained from Japanese adults at autopsy, fixed to a stereotactic frame, and examined with an operative microscope. The dimensions of each triangle were measured with calipers and compared, based on the same point and border. The anteromedial triangle and the superolateral (Parkinson's) triangle were more consistent in shape than the paramedial and oculomotor triangles, but the oculomotor triangle was larger in area than these other triangles. The posteromedial (Kawase's) triangle was more consistent in shape and larger than the anterolateral, lateral, and the posterolateral (Glasscock's) triangles. The anteromedial and superolateral (Parkinson's) triangles are important for the combined epi- and subdural approach to cavernous sinus lesions. The posteromedial (Kawase's) triangle is important for gaining access to the posterior cranial fossa from the middle cranial fossa.

Simultaneous display of MRA and MPR in detecting vascular compression for trigeminal neuralgia or hemifacial spasm: comparison with oblique sagittal views of MRI.

A new technique, simultaneous display of magnetic resonance angiography (MRA) and multiplanar reconstruction (MPR), was performed by a workstation to identify the involved vessels in patients with trigeminal neuralgia (TN) or hemifacial spasm (HFS), and the results were compared with those of oblique sagittal MRI technique. Twelve patients with either HFS or TN were prospectively assessed by simultaneous display of MRA and MPR, and oblique sagittal techniques, to point out the neurovascular compression and to identify the involved vessels. Three-dimensional (3D) time-of-flight (TOF) spoiled gradient-echo (SPGR) images were acquired to create MRA and MPR. Oblique sagittal views were also created and displayed on films. A total of 15 vessels in 12 patients were identified as compressing vessels during surgery. Simultaneous display of MRA and MPR technique pointed out the presence of vessels at and/or around root entry/exit zone (REZ) in all 12 patients, but proper identification by the name of the individual vessel was correct in 13 of 15 cases. However, oblique sagittal technique indicated the presence of vessels at and/or around REZ in 11 patients, but only 8 of 14 vessels were correctly identified. Our new method, simultaneous display of MRA-MPR, facilitated correct identification of the involved vessels compared with the oblique sagittal view method.

Postoperative oblique sagittal MR imaging of microvascular decompression for hemifacial spasm.

Pre-operative and postoperative oblique sagittal gradient-echo magnetic resonance (MR) imaging was used to evaluate micro-vascular decompression of the facial nerves in 26 patients with hemifacial spasm. The pre-operative MR images were divided into two groups as follows: 22 images in Group I, clear imaging of a high-intensity line and/or spot at the root exit zone (REZ) of the facial nerve; and 4 in Group II, and unreliable image around the REZ. Surgery found that the causative vessel was the vertebral artery (VA) in 9 cases and the anterior inferior cerebellar artery (AICA) or the posterior inferior cerebellar artery (PICA) in 13 cases in Group I, and the AICA or the PICA in the 4 cases in Group II. Postoperative MR imaging showed clear decompression as the high-intensity line and/or spot completely separated from the REZ by a low- and/or iso- intensity area in 9 cases of VA compression repositioned to the petrous dura matter, in 11 cases of PICA or AICA compression treated by shredded Teflon pledgets in Group I and in 3 cases in Group II. Postoperative MR imaging showed an incomplete separation of any high-intensity line and/or spot in the REZ in 2 cases of PICA or AICA compression in Group I and in one in Group II. The outcome was excellent in 22 of 23 cases with clear decompression, and in 1 of 3 cases of unclear decompression. Hemifacial spasm persisted in 3 cases. Oblique sagittal gradient-echo MR imaging is a useful method for postoperative follow-up which can demonstrate changes around the REZ of the facial nerve if hemifacial spasm recurs.

The role of intravascular embolization prior to radiosurgery of cerebral arteriovenous malformations. from the standpoint of hemorrhage and early obliteration after gamma knife radiosurgery.

The role of intravascular embolization prior to radiosurgery of cerebral arteriovenous malformations was evaluated based on the basis of the results of gamma knife radiosurgery in relation to hemorrhage and early obliteration after treatment. Nine of 213 patients experienced hemorrhage 4 to 42 months after radiosurgery. All AVMs in these patients had dilated feeding arteries, and the flow of the AVM was rapid and/or high. An intranidal aneurysm was seen in one patient. Drainage of all AVMs consisted of a single and/or deep draining veins, and venous obstruction was found in six. Sixty-three of 87 patients followed for more than four years after radiosurgery were examined angiographically, and total obliteration of AVM was observed in 52 of them (82.5%). Early obliteration was found in 19 of the 34 patients examined within 12 months. The obliteration rate was significantly higher in slow- and low-flow AVMs (73.9%) than in rapid- and/or high-flow AVMs (18.2%). It is concluded that the role of intravascular embolization prior to radiosurgery is not only decreasing the size of the AVM but decreasing the risk of hemorrhage and shortening the latency period by decreasing their flow rate and flow volume.

Prediction of vertebral artery compression in patients with hemifacial spasm using oblique sagittal MR imaging.

To discriminate between the various compressing vessels of the facial nerves in patients with hemifacial spasm, pre-operative oblique sagittal gradient-echo MR imaging was performed. Forty-two patients underwent pre-operative MR imaging and microvascular decompression. The MR images were divided according to findings into three groups as follows: Group A, a thick and/or long high-intensity line along the root exit zone (REZ) of the facial nerve; Group B, a thin and/or short high-intensity line along the REZ; and Group C, an unreliable image around the REZ. Fifteen images were classified as Group A, 19 as Group B, and 8 as Group C. In Group A, vertebral artery (VA) compression was confirmed intra-operatively in 12 cases and posterior inferior cerebellar artery (PICA) or anterior inferior cerebellar artery (AICA) compression in 3. In Group B, PICA or AICA compression was confirmed intra-operatively in all cases. In Group C, PICA or AICA compression was confirmed intra-operatively in 7 cases and no compression in one. In all cases of VA compression of the facial nerve, the oblique sagittal gradient-echo images demonstrated a thick and/or long high intensity line along the REZ. Oblique sagittal gradient-echo MR imaging is a useful preoperative planning aid, which can predict the possibility of VA compression prior to microvascular decompression for hemifacial spasm.

Visual recovery following immediate decompression of traumatic retrobulbar hemorrhage via transcranial approach.

A 17-year-old boy presented with retrobulbar hemorrhage manifesting as right proptosis, periorbital swelling, and blindness after suffering a midfacial trauma. Immediate decompression by removal of the retrobulbar hemorrhage via the transcranial approach was performed. The proptosis was resolved and visual acuity and eye movement were restored. Retrobulbar hemorrhage is a serious injury which may lead to blindness. However, recovery from blindness can be achieved with adequate management including neurosurgical decompression in the early stage.

Palatal myoclonus induced by extirpation of a cerebellar astrocytoma. Case report.

A 45-year-old woman developed a rare case of palatal myoclonus with no other neurological signs after undergoing extirpation of a small cerebellar low-grade astrocytoma that was located in the right dentate nucleus. The palatal myoclonus has persisted for 4 years after the operation. Magnetic resonance T2-weighted imaging revealed a high-intensity lesion in the left inferior olive. Palatal myoclonus associated with the removal of cerebellar tumors is unusual but may easily be overlooked.

Music alexia in a patient with mild pure alexia: disturbed visual perception of nonverbal meaningful figures.

A 26-year-old female pianist suffered from an intracerebral hematoma caused by an arteriovenous malformation of the left occipital parasplenial region, which was operated on seven months after the onset. Incomplete right hemianopsia, mild pure alexia, and partially disturbed naming of visual objects persisted several months after the removal of the malformation. Evaluation of musical ability one and three months after surgery showed that her auditory recognition of music was intact. She could sing and play melodies already learned and could dictate well the notes after hearing tones. However, she had difficulty in reading music, especially the pitch of notes, even for simple sequences of 4 notes. In contrast, her rhythm reading was fairly good. Her visual recognition of other symbolic figures like road signs was also markedly impaired. These results suggest that her visual recognition of written music as well as of other symbolic figures underwent a preliminary verbal decoding in the left hemisphere and that pitch reading was more dependent on verbal processing than rhythm reading.

Oblique sagittal magnetic resonance imaging visualizing vascular compression of the trigeminal or facial nerve.

An oblique sagittal magnetic resonance (MR) imaging method was developed to provide better visualization of vascular compression of nerves. The MR images of 12 patients with trigeminal neuralgia and 24 with hemifacial spasm were analyzed. The oblique sagittal views were obtained along the nerve identified by the axial view at an angle of 105 degrees between the line along the dorsal brain stem and the line along the margin of the pontomedullary junction (in patients with hemifacial spasm) or by the midsagittal view through the midpons (in patients with trigeminal neuralgia). The T1- and T2-weighted, proton-density, and/or gradient-echo MR images were evaluated to optimize imaging conditions. The oblique sagittal gradient-echo MR image most clearly visualized vascular compression of the nerves as high-intensity lines in six patients with trigeminal neuralgia, which was confirmed intraoperatively in four. Fifteen (75%) of 20 oblique sagittal gradient-echo MR images demonstrated vascular compression of the facial nerves in patients with hemifacial spasm; 12 of these were confirmed intraoperatively. The control study used 15 oblique sagittal gradient-echo MR images of nonaffected contralateral and normal sites. Four false-positive findings were found. Oblique sagittal gradient-echo MR images are a useful planning aid, allowing differential diagnosis prior to microvascular decompression in trigeminal neuralgia and hemifacial spasm.

[Superior sagittal sinus thrombosis complicated with multiple aneurysms presenting as subarachnoid hemorrhage. Case report].

A 48-year-old female suffered from severe headache, vomiting, and disturbance of consciousness. On admission, she was somnolent with mild paresis of the left leg. Precontrast computed tomography (CT) scans showed a high-density area in the left sylvian fissure and the posterior horn of the left lateral ventricle. Angiographically, a right middle cerebral artery aneurysm and a basilar artery aneurysm were recognized. Furthermore, on the venous phase of bilateral carotid angiograms, superior sagittal sinus (SSS) thrombosis was recognized. Subarachnoid hemorrhage (SAH) was probably induced by rupture of a dilated vein associated with SSS thrombosis, because high-density area on CT scan and location of the aneurysms were different. The patient was initially treated conservatively. Two months later, craniotomy was performed which did not disclose any trace of hemorrhage around the aneurysms and aneurysms themselves. Postoperatively, acute brain swelling and generalized convulsion were induced. The patient became ambulatory 5 months after surgery. In SAH cases, the venous phase should be examined at least in one side of the carotid arteries. In such a SAH case induced by venous thrombosis complicated by aneurysms it is very difficult to decide the timing of surgery for aneurysms.

Cytometric analysis of the thalamic ventralis intermedius nucleus in humans.

1. The cytoarchitecture and the exact borders of the thalamic ventralis intermedius (Vim) nucleus of humans as originally delineated by Hassler (17) have been studied on the basis of stereotaxic coordinates correlated with Nissl- and Golgi-impregnated sections, using a microscopic image analyzer. 2. The Vim nucleus forms part of a relatively "cell-sparse zone" which includes the other ventrolateral thalamic subnuclei. It is distinguished by the presence of darkly stained, large and medium sized, angular cells with areas of approximately 500-1,000 microns 2 and 300-400 microns 2, respectively, and a cell density of approximately 50-90 (mean 65)/mm2 in 50-microns-thick sections. 3. Both sets of neurons have the characteristics of thalamocortical relay neurons in Golgi preparations. Large neurons have rectangular or square somata 30-50 microns diam and are concentrated mainly in the lateral and ventral two-thirds of the nucleus. The medium neurons have square to round somata, 15-25 microns diam, and are distributed homogeneously through the nucleus. The total dendritic arborization of both types is usually symmetrical in all directions and at least 500-600 microns diam. 4. The borders between the Vim nucleus and the Nucleus ventrooralis (Vo) and between the Vim nucleus and the Nucleus ventrocaudalis internus (Vci) are clearly identified by clearcut differences in cell size and cell density. The borders between the Vim nucleus and the Nucleus ventrooralis internus (Voi) and between the Vim nucleus and the Nucleus zentrolateralis intermedius (Zim) are quite obscure, and these nuclei, with Vim, seem to be parts of the large cell sparse zone comparable to that described in monkeys as VLp or VL. The border between the Vim nucleus and the Nucleus ventrocaudalis externus anterior (Vcea) is also unclear but the increased cell density and intermingling of small and medium-to-small neurons with large neurons are the major features that distinguish the Vcea nucleus from the Vim nucleus cytometrically. 5. The position and anatomic organization of the human Vim nucleus make it likely that it is the region in which kinesthetic response were recorded in the accompanying paper but extension of the recording sites into the Vcea nucleus cannot be ruled out.

Primary internal ophthalmoplegia due to head injury.

Six cases of internal ophthalmoplegia due to direct head injury are presented. All six patients had a dilated, nonreactive pupil. Four had no extraocular palsies or ptosis and two had partial extraocular palsies or ptosis. Disturbance of consciousness was absent or very mild, and all patients fully recovered within 1 to 7 days after the traumatic event. No patient had a history that suggested a cause for oculomotor nerve palsy, and emergency CTscans showed no mass lesions. The internal ophthalmoplegia was recognized immediately after trauma. Although minimal oculomotor nerve palsies due to unruptured intracranial aneurysms have been described, none of our patients complained of periorbital or retroorbital pain either before or after the trauma, which rules out intracranial aneurysms as the cause of the internal ophthalmoplegia. Therefore, we concluded that the internal ophthalmoplegia was due to direct head injury. The pathophysiological mechanism of the internal ophthalmoplegia appeared to be slight injury of the pupillomotor fibres on the ventromedial surface of the third nerve at the posterior petroclinoid ligament, which acted as the fulcrum due to the downward displacement of the brainstem at the time of impact.

Long-term observations in cases with spontaneous carotid-cavernous fistulas.

Twenty-six cases with spontaneous carotid-cavernous fistulas were followed up for periods ranging between 4 months and 9 years 8 months. A complete regression of symptoms without reappearance for more than 6 months was noted in 19 cases, a marked improvement in 2 cases, and a moderate regression in 3 cases. In 2 cases, symptoms have continued for 9 years 8 months and for 1 year. The regression of symptoms was usually delayed in patients less than 60 years old, in cases in which the symptoms developed slowly, and in cases with multiple draining veins. According to our observations a regression of symptoms may occur after very slight changes of haemodynamics. Compression of the cervical carotid artery for a short time or a temporary occlusion of the carotid artery by a balloon catheter should be considered as the treatment of choice in the first instance in cases with spontaneous carotid-cavernous fistulas showing relatively low pressure and low flow shunt.

Symmetrical bilateral low-density lesions in the areas of supply by Heubner's arteries after aneurysm surgery.

Three patients with symmetrical bilateral low-density areas which were the perfusion territories of Heubner's arteries are reported. The infarctions were demonstrated on computed tomography after aneurysm surgery. Two of them had an anterior communicating artery aneurysm and the other one had multiple aneurysms of both sides. They were operated upon in the acute stage after subarachnoid haemorrhage. As common factors, a thick and diffuse subarachnoid haemorrhage, an acute-stage operation, temporary clips to bilateral A1 segments or the internal carotid artery and a relatively low systemic blood pressure during operation were found. From these findings we conclude that the pathogenesis of the infarctions was due to occlusive changes affecting Heubner's arteries bilaterally.

Postoperative extradural hematomas: computed tomographic survey of 1105 intracranial operations.

We reviewed the computed tomographic findings after 1055 intracranial operations to determine the incidence of postoperative extradural hematomas. There were 11 medium and 5 large hematomas after 1055 operations (1.0%). Ten of the 16 hematomas were operated upon (10/1055, 0.9%). Four of the 10 hematomas were seen after 278 brain tumor removals (1.4%), another four after 190 aneurysmal operations (2.1%), one after 14 intracerebral hematoma removals (7.1%), and the last one after 251 ventricular shunting or drainage procedures (0.4%). In 4 of the 10 operated hematomas, sites were regional, in five sites were adjacent, and in one the site was distant. All of the five adjacent hematomas extended downward from a lower rim of the operative locus. Causes were analyzed in the three types of the hematomas. In case of the regional hematomas, the causes were incomplete hemostasis of the dura mater or the bone in all four patients, nonperformance of central stay sutures in three, systemic hypertension in one, and hypofibrinogenemia in one. In the adjacent hematomas, we could find dural separation at an edge of craniotomy in all five patients, abrupt collapse of the brain in all, ventricular dilatation in two, and systemic hypertension during immediate postoperative period in two. In one distant hematoma, ventricular dilatation and ventricular shunting procedure were themselves thought to be the causal factors.

Long-term follow-up results of selective VIM-thalamotomy.

The authors report the results of a long-term follow-up study of the effects of the physiologically defined selective VIM (nucleus ventralis intermedius)-thalamotomy on tremor of Parkinson's disease in 27 patients and essential tremor in 16 patients. The follow-up period ranged from 3.25 to 10 years (mean 6.58 years). In 43 patients a total of 50 operations (including four bilateral operations and three reoperations) were carried out. The early (2 to 4 weeks after surgery) and late effects on the tremors were determined clinically and electromyographically. Fourteen parkinsonian cases were treated with minimal lesions (about 40 cu mm). Their late results were very similar to the early results: in 10, the tremors were completely abolished, three had a slight residual tremor, and one underwent reoperation 3 months after the first surgery. Eleven essential tremor cases were treated with minimal lesions. Six of these tremors were completely abolished, four patients had slight residual tremors, and one patient with a recurrence underwent reoperation 2 years after the initial surgery. In these 23 successful operations with minimal lesions (excluding two cases with reoperation), the tremor was abolished without discernible long-lasting side effects. The other 23 operations on 16 patients with Parkinson's disease (including one reoperation) and on seven with essential tremor (one of whom also had a minimal lesion on the other side) involved relatively large lesions. In this group, the surgery was successful in almost every case. It was concluded that radiographically and physiologically monitored selective VIM-thalamotomy for parkinsonian and essential tremor is effective even when lesioning is minimal. Moreover, the beneficial effect is maintained over a long period of time.

[Long-term follow-up study of selective VIM-thalamotomy].

To evaluate the effect of the physiologically defined selective Vim-thalamotomy on tremor type Parkinson's disease (PA, 26 cases) and essential tremor (ESS-T, 16 cases), a long-term follow-up study was conducted. The follow-up time extended from 4 months to 7 years (mean: 3.6 years). On 42 cases a total of 49 operations (4 bilateral surgery and 3 reoperations) were carried out. After identifying kinesthetic neuron, the coagulative lesion was made by using Leksell's apparatus between two needles of 4 mm effective tip length located with 3 mm interval including the recording point. One coagulation (unit lesion) destroyed about 20 mm3 brain tissue taking account of the mechanical damage by the needles themselves. The unit lesion was added around an imaginary cylinder of 3 mm radius, until the tremor was abolished completely. On the basis of number of unit lesion and its extent within an imaginary cylinder, these 49 operations were divided into the following group. Group I (minimal lesion group): coagulative lesion of 1 to 3 units within a quadrant of the imaginary cylinder. Group II: 3 to 5 units within 1/2 to one cylinder. The early (14 days after operation) and the late results on the tremor were evaluated clinically and electromyographically by 4 different categories: complete abolition, slight residual, residual, and recurrence in a strict sense. The late results in 13 PA cases of group I (similar to the early results) were: 10 complete abolition, 2 slight residual and one recurred, this case was reoperated 3 months after first operation and therefore categolized in group II. The late results in 11 ESS-T cases of group I were: 6 complete arrest, 4 slight residual, and one recurred case, which had been reoperated 2 years after operation. Therefore in a total of 24 minimal lesioned cases with PA and ESS-T complete abolition in 16, slight residual in 6, and 2 reoperated cases. In these successful 22 cases with minimal lesion, the tremor was abolished without noticeable long-lasting side effect. In other 20 cases with PA and ESS-T of group II, the tremor was almost completely relieved and maintained. In conclusion, by radiographically and physiologically controlled selective Vim thalamotomy for Parkinsonian and essential tremor, it was shown that the effect of minimal lesion was valid and well maintained on the long-term follow-up base.

The incidence of delayed traumatic intracerebral hematoma with extradural hemorrhages.

After introduction of computerized tomography (CT), we experienced 22 patients with traumatic extradural and intracerebral combined hematomas, of whom 15 underwent sequential CT scans. In 14 of the 22 patients or 13 of the 15 patients whose initial CT scans were performed early, within 6 hours after injury, intracerebral hematomas developed more slowly than extradural hematomas. In ten of the 13 patients, development of intracerebral hematomas was demonstrated only after removal of extradural hematomas, and in four patients acute brain swelling was observed during surgery. Therefore it is emphasized that the incidence of post-surgical intracerebral hematoma with extradural hemorrhages is high and that acute brain swelling during surgery for extradural hematomas is largely caused by the delayed intracerebral hematomas.