Various patterns of the middle cerebral vein and preservation of venous drainage during the anterior transpetrosal approach.

OBJECTIVE: The drainage of the superficial middle cerebral vein (SMCV) has previously been classified into 4 subtypes. Extradural procedures and dural incisions during the anterior transpetrosal approach (ATPA) may interrupt the route of drainage from the SMCV. In this study, the authors examined the relationship between anatomical variations in the SMCV and the corresponding surgical modifications to the ATPA that are necessary for venous preservation. METHODS: This study included 48 patients treated via the ATPA in whom the SMCV was examined using 3D CT venography. The drainage patterns of the SMCV were classified into 3 types: cavernous or absent (Type 1), sphenobasal (Type 2), and sphenopetrosal (Type 3). Type 2 was subdivided into medial (Type 2a) and lateral (Type 2b), and Type 3 was subdivided into vein (Type 3a), vein and sinus (Type 3b), and sinus (Type 3c). The authors performed 3 ATPA modifications to preserve the SMCV: epidural anterior petrosectomy with subdural visualization of the sphenobasal vein (SBV), modification of the dural incision, and subdural anterior petrosectomy. Standard ATPA can be performed with Type 1, Type 2a, and Type 3a drainage. With Type 2b drainage, an epidural anterior petrosectomy with subdural SBV visualization is appropriate. The dural incision should be modified in Type 3b. With Type 3c, a subdural anterior petrosectomy is required. RESULTS: The frequency of each type was 68.7% (33/48) in Type 1, 8.3% (4/48) in Type 2a, 4.2% (2/48) in Type 2b, 14.6% (7/48) in Type 3a, 2.1% (1/48) in Type 3b, and 2.1% (1/48) in Type 3c. No venous complications were found. CONCLUSIONS: The authors propose an SMCV modified classification based on ATPA modifications required for venous preservation.

Anterior Transpetrosal Approach Combined with Partial Posterior Petrosectomy for Petroclival Meningiomas with Posterior Extension.

BACKGROUND: An anterior transpetrosal approach (ATPA) is suitable for treating upper petroclival lesions. However, the limit of the ATPA is reached when the tumor extends posterolaterally over the internal auditory canal (IAC) along the petrous edge. In such cases, ligation of the posterior part of the superior petrosal sinus (SPS) is necessary. To overcome this limitation, we combined the ATPA with a partial posterior petrosectomy in 8 patients who had petroclival meningiomas extending posterolaterally over the IAC. METHODS: We resected only the Trautmann triangle in addition to the Kawase triangle to secure the space to ligate the posterior portion of the SPS. Because the tympanic cavity and bony labyrinth of the ear were not exposed, we were able to preserve hearing function and lower the risk of cerebrospinal fluid leakage. Furthermore, this approach enables easy ligation of the SPS and the tentorium posterior to the tumor attachment. This combined technique also allows visualization of the petrosal vein, which is important for surgery of the posterior fossa. RESULTS: Total and near-total tumor removal was achieved in 6 patients (75%) with no permanent complications and no cerebrospinal fluid leakage. Postoperative hearing impairment was not found in any of the patients who underwent this surgery. CONCLUSIONS: The ATPA combined with partial posterior petrosectomy is an effective method for removal of complicated petroclival meningiomas that extend posterolaterally over the IAC along the petrous edge.

Epidural anterior petrosectomy with subdural visualization of sphenobasal vein via the anterior transpetrosal approach--technical case report.

The drainage of the superficial middle cerebral vein (SMCV) is classified into four subtypes. The sphenobasal vein (SBV) drains from the SMCV to the pterygoid venous plexus at the temporal skull base. Epidural procedures in the standard anterior transpetrosal approach (ATPA) may damage the route of the SBV. We report a case in which modified surgical procedures via the ATPA were used to preserve the SBV. A 45-year-old man complained of right facial pain. Magnetic resonance images revealed a right cerebellopontine tumor suggestive of an epidermoid cyst. Right carotid angiography revealed that the SMCV drained into the pterygoid venous plexus via the SBV. The convexity dura mater of the temporal lobe was cut and the anterior part of the temporal lobe was retracted subdurally. The SBV was visualized from the subdural side. The basal dura mater of the temporal lobe posterior to the SBV was cut and the posterior part of the temporal lobe was retracted epidurally. After dissecting the dura mater medial to the greater petrosal nerve and to the edge of the petrous apex, the petrous apex was exposed and drilled out without injuring the SBV. The superior petrous sinus and the tentorium were cut. The tumor compressed the root exit zone of the trigeminal nerve. The tumor was grossly totally removed. The modified ATPA (epidural anterior petrosectomy with subdural visualization of the SBV) is effective in preserving the SBV.

Assessment of cognitive function before and after surgery for posterior cranial fossa lesions using computerized and conventional tests.

Cognitive function has not been well studied after neurosurgery for posterior fossa lesions despite its potential importance in determining surgical indications and approaches. The present study evaluated changes in cognitive functions after posterior fossa surgery to detect any differences between the middle cranial fossa and lateral suboccipital approaches in 50 patients with posterior fossa lesions such as tumors and vascular diseases. Twenty-five patients underwent surgery via the middle fossa and 25 via the lateral suboccipital approaches. Computerized test battery (CogState) and conventional neuropsychological tests (serial seven-word learning test and mini-mental state examination) were examined before, 1 month after, and 3 months after surgery. All scores of the neuropsychological tests remained within normal limits after surgery. However, the scores of one computerized test battery and serial seven-word learning tests decreased significantly 1 month after surgery and recovered within 3 months, indicating temporary deterioration of short-term memory in the middle fossa group. The computerized tests detected significantly larger numbers of patients with worsened results than the conventional tests. The middle fossa approach and operation time showed correlations with the postoperative neuropsychological declines. The computerized tests could be performed easily and were beneficial for detecting subtle changes of the cognitive function after surgery. Cognitive function, especially short-term memory, may decline temporarily with the middle fossa approach and long operation time.

Motor-related intracortical steal phenomenon detected by multichannel functional near-infrared spectroscopy imaging.

BACKGROUND: Patients with severe cerebral ischemia may lose autoregulation to increase cerebral blood flow following neural activity. Although the steal phenomenon under conventional cerebral blood flow study has been known as a high-risk factor for stroke, the cerebral oxygen hemodynamics in ischemic patients during functional activation has not been thoroughly investigated. In this study, we present rare cases with intracortical steal phenomenon during motor tasks detected by multichannel functional near-infrared spectroscopy before and after surgery. METHODS: The relative concentration change of oxygenated, deoxygenated and total hemoglobin in and around the primary sensorimotor cortex during contralateral hand grasping was investigated in 11 patients with severe internal carotid artery stenosis. RESULTS: In 3 patients, the concentration of total hemoglobin around the primary sensorimotor cortex significantly decreased in response to motor stimulation and returned to baseline soon after termination of the motor task. This phenomenon partially disappeared postoperatively in all patients who underwent surgery. The remaining 8 patients showed no signs of total hemoglobin decrease in and around the sensorimotor cortex. In 9 patients, lack of decrease in deoxygenated hemoglobin in the center of the primary motor cortex during the motor task was observed and 3 of them showed significant increase in deoxygenated hemoglobin. CONCLUSIONS: We have demonstrated that in some patients with severe ischemia, an abnormal motor-related steal phenomenon can be observed. This phenomenon can be modulated by surgical intervention and might imply the severity of ischemia.

Treatment of spontaneous intracranial hypotension secondary to C-2 meningeal cyst by surgical packing--case report.

A 41-year-old man presented with progressive worsening of postural headache. Computed tomography (CT) showed bilateral subdural hematomas without prior history of trauma. The diagnosis was spontaneous intracranial hypotension (SIH). Conservative treatment with oral steroids failed to prevent gradual deterioration of the patient's consciousness. CT myelography revealed massive cerebrospinal fluid (CSF) leakage between the C-1 and C-2 levels. The leak was repaired surgically via a laminectomy. A cyst, thought to be a meningeal cyst, was discovered adjacent to the right C-2 nerve root, and CSF was seen seeping out from around the cyst after a Valsalva maneuver. The presumed dural defect of the cyst was sealed by packing with muscle fragments and fibrin glue. The symptoms disappeared soon after surgery. He was discharged 1 month after surgery without deficits. Most SIH cases are benign and can be managed conservatively, or by the epidural blood patch method. Surgery is more invasive than the epidural blood patch method, but should be performed in patients with a high cervical lesion and massive CSF leakage.

Cerebellar hemorrhage secondary to cranial metastasis of prostate cancer--case report.

A 77-year-old man with a 9-year history of prostate cancer presented with high fever and dysphagia. The initial diagnosis was aspiration pneumonia, but the patient became comatose 2 days after admission, and neuroradiological workup revealed cerebellar hemorrhage, obstructive hydrocephalus, and extensive destruction of the occipital bone secondary to cranial metastasis. The diagnosis was cerebellar hemorrhage secondary to cranial metastasis of prostate cancer. Tumor resection was abandoned because of the patient's poor health. Shunt surgery and palliative radiotherapy were temporarily effective in restoring his consciousness, but he died of systemic infection 3 weeks after surgery. Metastasis of prostate cancer to the cranium, particularly to the skull base, rarely causes lower cranial nerve paresis, and awareness of this sign may lead to earlier detection of the cranial metastasis and prevention of cerebellar hemorrhage.

Postoperative communicating hydrocephalus in patients with supratentorial malignant glioma.

Postoperative communicating hydrocephalus in adult patients with supratentorial malignant glioma is a relatively uncommon condition that occurs months after the initial operation of tumor excision. It occurred in only five of 50 consecutive cases treated in our department during the past 10 years. The hydrocephalus appeared to be attributable to leptomeningeal dissemination of tumor cells and subsequent impairment in cerebrospinal fluid (CSF) absorption. The tumors were located adjacent to the lateral ventricles in all five patients, and the proximity of the tumor to the cerebral ventricles may have facilitated dissemination of the tumor cells into the CSF space, resulting in hydrocephalus. The hydrocephalus was treated by a shunt surgery in all five cases, and the symptoms temporarily improved. None of the five patients experienced shunt malfunction or abdominal symptoms attributable to metastasis to the peritoneal cavity, and all five patients died of regrowth of the intracranial tumor or of pneumonia.

"Occult" ruptured cerebral aneurysms revealed by repeat angiography: result from a large retrospective study.

Not infrequently, cerebral angiography performed immediately after the onset of subarachnoid hemorrhage (SAH) fails to reveal any causative lesion. Although the cause of the SAH in most of these cases remains unknown, repeat angiography sometimes discloses a lesion not detected by the initial angiography. The frequency of finding a ruptured aneurysm by repeat angiography and the angiographic characteristics of such aneurysms have been investigated retrospectively. Nineteen among 316 non-traumatic SAH patients (6%) showed initially negative angiogram, and 7 of 19 patients (36%) were identified as harboring an "initially occult" aneurysm. It was possible to identify the expected cause of these initial false-negative angiograms in four of those seven patients. The aneurysm was located in the anterior communicating artery (ACoA) complex in four of the seven patients. When interpreting the angiograms of patients with SAH, neurologists and neurosurgeons should bear in mind the finding that the ACoA complex is the most frequent site of "initially occult" aneurysms. One patient had a dissecting aneurysm of the internal carotid artery, and although such lesions have been considered rare, they should be included in the differential diagnosis of SAH of unknown origin.

[Calcified chronic subdural hematoma complicated with subcortical hemorrhage: case report].

The patient was a 46-year-old male, who suffered from mild head trauma in January 2002, and general convulsions with unconsciousness on February 28. Slight right hemiparesis and aphasia were presented after the epilepsy attack. CT scan revealed a large lesion of mixed density occupying the left temporal space. It showed linear high density in its medial margin and had compressed the left temporal lobe strongly, causing mid-line shift. The lesion was suspected to be a calcified chronic subdural hematoma and the patient was admitted to our hospital on February 28. The symptoms had improved the next day but they began to get worse again gradually after admission. T1-weighted MR image showed high intensity areas under the subdural hematoma, which were suspected to be subcortical hemorrhage. Six days after admission, consciousness disturbance became progressive. The calcified hematoma had not enlarged but brain edema had increased. On CT, an operation was performed and the calcified old hematoma and the new subdural hematoma surrounding it were removed. The diagnosis of organized chronic subdural hematoma was made at the time of the operation. The contents of this calcified subdural hematoma was mostly old dark-gray substance, but some fresh bleeding point was seen at the inner surface of the outer membrane. At the bottom there was a hard, calcified layer which adhered tightly to the brain. Adhesion between the inner membrane of the hematoma and brain surface which related to the subcortical hemorrhage was presented. It seemed impossible to remove the inner membrane without damaging the brain so no attempt was made to do so. The aphasia and right hemiparesis improved 3 weeks after the operation and the patient was discharged on April 4. He has no neurological deficits and is under periodic observation. A calcified chronic subdural hematoma has rarely been encountered and the etiology, imaging diagnosis, and management are unclear. We presented the interesting image findings on this case and discussed the etiology of this disease.

[Aseptic meningitis as a complication caused by an allergic reaction after microvascular decompression: two case reports].

We report here two cases of patients complicated with aseptic meningitis after microvascular decompression (MVD). The first case, a 56-year-old female complained of headache with high fever 18 days after the MVD for right trigeminal neuralgia. The amount of cells in cerebrospinal fluid (CSF) had so much increased that bacterial meningitis was suspected. However, there was no improvement after antibiotics therapy, so immune globulin was injected and the meningitis gradually improved. Eosinophilia remained in peripheral blood and the symptoms improved rapidly after the steroid therapy. Because of this, we suspected that meningitis was caused by an abnormal allergic reaction. The second case, a 30-year-old male complained of headache with mild fever 15 days after MVD for left hemifacial spasm. The amount of cells in CSF increased, so bacterial meningitis was suspected. Eosinophilia remained in peripheral blood and the steroid therapy proved very effective for the meningitis. Because of this, we suspected that meningitis was caused by an abnormal allergic reaction. We suspected that the two patients suffered from aseptic meningitis caused by allergic reaction, and the antigen for this abnormal allergic reaction was the foreign materials used for MVD. The materials were Dacron for prostesis, Goatex or Lyodula for dural plasty, fibrin glue for preventing CSF leakage. We ascertained that the abnormal allergic reaction was caused by human fibrinogen in the second case. It is important to be aware of such allergic reaction to fibrin glue in the post-operative stage after MVD.

[A dissecting aneurysm of the posterior inferior cerebellar artery was reduced spontaneously during conservative therapy: case report].

We report here a case of a patient with a dissecting aneurysm of the anterior medullary segment of the posterior inferior cerebellar artery (PICA) which presented with Wallenberg's syndrome. A 32-year-male presented with an unusual case of Wallenberg's syndrome due to a dissecting aneurysm of the PICA manifesting as a sensation of heaviness in the occipital region and vertigo. The occipital symptoms persisted and vertigo and vomiting developed after 6 days. Numbness developed on the left side of the patient's face, and hyperalgesia on the right side of the body. The diagnosis of Wallenberg's syndrome was based on the above findings. MRI revealed infarction of the lateral aspect of the medulla oblongata and MR angiography revealed dilatation in the proximal portion of the left PICA. Digital subtraction angiography revealed that the left vertebral artery was essentially normal, but there was a spindle-shaped dilatation in the proximal portion of the left PICA. We carried out conservative therapy at the patient's request and 3D-CTA revealed that the dissecting aneurysm was markedly reduced in size seven months after the onset. Dissecting aneurysms of the intracranial posterior circulation have been shown to be less uncommon than previously thought. However, those involving the PICA without involvement of the vertebral artery at all are extremely rare. The natural history of the dissecting PICA aneurysm was unknown, and the indication for surgical treatment of such aneurysms remains controversial. Management options are conservative treatment, open surgical treatment including wrapping, trapping, and resection with reconstruction, but almost all of the patients underwent radical treatment to prevent rupture of the aneurysm. However we had no knowledge of the risk of rupture of a PICA dissecting aneurysm presenting with ischemic symptoms. We have reviewed the well-documented 15 cases of dissecting aneurysms of the PICA reported in the literature and we discuss the management of the dissecting PICA aneurysm presenting with ischemic symptoms.