Surgical strategy for intracranial hemorrhage with accidental hypothermia in elderly individuals.

Background: Accidental hypothermia poses a significant threat to the elderly, and its prevalence might increase due to aging and increasing isolation of individuals in Japan. Here, a series of four consecutive cases of accidental hypothermia in elderly patients with intracranial hemorrhage who underwent surgical treatment at our institution is presented. Case Description: All patients were admitted to the emergency department with a diagnosis of intracranial hemorrhage. Among them, two patients experienced acute circulatory failure during emergency surgery, necessitating immediate cardiopulmonary resuscitation. Two other patients required intensive care before surgery; however, one of them exhibited signs of impending cerebral herniation, requiring emergency surgery. Conclusion: Accidental hypothermia poses a significant threat to elderly individuals, carrying a substantial mortality risk and demanding intensive general care. During rewarming, careful considerations must be devoted to potential complications, such as ventricular fibrillation, rewarming shock, bleeding diathesis, and hyperkalemia. Despite these risks, many life-threatening cases necessitate emergency surgery and rewarming procedures in parallel. The formulation of a surgical strategy aimed at mitigating rewarming-related complications should be entrusted to anesthesiologists. Strict follow-up is required to increase intracranial pressure when prioritizing intensive care over surgery.

5­aminiolevulinic acid induces a radiodynamic effect with enhanced delayed reactive oxygen species production under hypoxic conditions in lymphoma cells: An in vitro study.

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive type of intracranial tumor. However, PCNSL is radiosensitive; thus, whole-brain radiotherapy (WBRT) is often selected as an alternative consolidation therapy. WBRT-related delayed neurotoxicity can affect the quality of life of the elderly. 5-aminolevulinic acid (ALA) is a natural precursor of heme and has been widely used as a live molecular fluorescence marker in brain tumor surgery. Experimental studies have demonstrated that combination therapy with 5-ALA and ionizing irradiation (IR), denoted radiodynamic therapy (RDT), resulted in tumor suppression in cancer, including glioma, melanoma, colorectal cancer, prostate cancer, breast cancer and lung cancer; however, to the best of our knowledge, this method has not been investigated in lymphoma. The present study aimed to investigate the radiodynamic effect of 5-ALA on lymphoma cells in vitro. The synthesis of 5-ALA-induced protoporphyrin IX (PpIX) was assessed under normal and hypoxic conditions in lymphoma cells (Raji, HKBML and TK). Subsequently, the radiodynamic effect of 5-ALA was evaluated using a colony formation assay and reactive oxygen species (ROS) production after RDT was examined using flow cytometry. Finally, the mitochondrial density in the lymphoma cells was evaluated. Lymphoma cells exhibited a high accumulation of 5-ALA-induced PpIX in the flow cytometric analysis, and a decrease in the surviving fraction under IR in cells with 5-ALA treatment compared with cells not treated with 5-ALA in the colony formation assay under normal and hypoxic conditions. Although ROS production 12 h after IR was increased compared with that immediately after IR (0 h), pretreatment with 5-ALA enhanced the delayed ROS production in each lymphoma cell line under normoxic conditions. Raji and TK cells exhibited an increase in ROS production 12 h after IR compared with that at 0 h in the 5-ALA-untreated cells under hypoxic conditions. Raji, HKBML and TK cells exhibited an increase in ROS production 12 h after IR compared with that at 0 h in the 5-ALA-treated cells, while TK cells exhibited enhancement of ROS production 12 h after IR in 5-ALA-treated cells compared with 5-ALA-untreated cells under hypoxic conditions. Other studies have demonstrated that impaired mitochondria damaged by IR produce ROS via the metabolic process, then damage the rest of the surrounding normal mitochondria, consequently propagating oxidative stress within tumor cells and leading to cell death. Thus, we hypothesized that the propagating oxidative stress after IR was associated with mitochondrial density in tumor cells. Namely, high accumulation of 5-ALA-indcued PpIX may promote ROS production in mitochondria of tumor cells after IR, and suppress the cell surviving fraction via the propagation of oxidative stress. In the colony formation assay, Raji cell colony formation was suppressed by RDT with 5-ALA. Simultaneously, the mitochondrial density in the Raji cells was higher than that in other cell lines. Pretreatment with 5-ALA enhanced delayed ROS production after IR in lymphoma cells under normoxic conditions. Under hypoxic conditions, only TK cells exhibited enhancement of ROS production 12 h after IR in the 5-ALA-treated group compared with the 5-ALA-untreated group. Although further studies evaluating the effect of hypoxic conditions in lymphoma cells are needed, the results suggested that RDT with 5-ALA could suppress colony formation under normal and hypoxic conditions in lymphoma cells. Therefore, RDT with 5-ALA is a potential treatment option for PCNSL.

Clinical Images: Symmetrical Gyriform Restricted Diffusion in Severe Reversible Cerebral Vasoconstriction Syndrome.

A 45-year-old woman with chronic depression and currently receiving dual serotonergic therapy was transferred to our department with sudden dysbasia; she also reported an antecedent thunderclap headache. Magnetic resonance imaging (MRI) revealed a symmetrical bilateral acute infarction in the medial parietal lobe and severe vasoconstriction in the cerebral arteries. We diagnosed reversible cerebral vasoconstriction syndrome (RCVS) and stopped the serotonergic drug regimen. Her symptoms improved after receiving a calcium blocker and magnesium sulfate, and she was discharged after 20 days. Cerebral infarctions developed in 30%-40% of reversible cerebral vasoconstriction syndrome (RCVS) cases, mostly within watershed regions; however, these atypical infarctions were bilateral and symmetrical, potentially because of hypoperfusion caused by long-lasting severe vasoconstriction in the anterior cerebral arteries. Rare bilateral neurologic deficits can be mistaken for hypochondriac delusions, particularly in patients with depression. Since serotonergic drugs are the main cause of RCVS, primary care psychiatrists must be aware of drug-induced RCVS.

Intra-arterial Contrast-enhanced Micro-computed Tomography Can Evaluate Intracranial Status in the Ultra-early Phase of Experimental Subarachnoid Hemorrhage in Rats.

The endovascular perforation (EP) model is a common technique for experimental subarachnoid hemorrhage (SAH) in rats, simulating the pathophysiological features observed in the acute phase of SAH. Due to the drawbacks of large variations in the amount of bleeding, the results obtained from this model require severity evaluation. However, no less-invasive procedure could confirm the precise intracranial conditions immediately after establishing the rat EP model. We created a novel method for evaluating SAH immediately after establishing the rat EP model using intra-arterial contrast-enhanced micro-computed tomography (CT). We administered contrast agents continuously via the carotid artery during surgery and performed CT examination immediately after SAH induction. First, bleeding severity was classified by establishing a scoring system based on the CT findings (cSAH scoring system). Subsequently, we determined the actual SAH distribution macroscopically and histologically and compared it with the cSAH scores. Second, we investigated the contrast agent's neurotoxicity in rats. Finally, we confirmed the correlation between cSAH scores and SAH severity, including neurological status, cerebral vasospasm, and hematoma volume 24 hr after SAH. Intra-arterial contrast-enhanced micro-CT could visualize the distribution of SAH proportionally to the bleeding severity immediately after establishing the EP model. Moreover, the contrast agent administration was determined not to be neurotoxic to rats. The cSAH scoring revealed a significant correlation with the SAH severity in the rat EP model (P <0.01). Thus, our minimally invasive method provided precise information on intracranial status in the ultra-early phase of SAH in rats EP model.

5-Aminolevulinic Acid: Pitfalls of Fluorescence-guided Resection for Malignant Gliomas and Application for Malignant Glioma Therapy.

5-Aminolevulinic acid (ALA) has been widely used as an intravital fluorescence marker in the fluorescence-guided resection of malignant gliomas. Although not a photosensitizer itself, 5-ALA is a prodrug that accumulates protoporphyrin IX (PpIX) in the mitochondria of glioma cells; PpIX acts as a photosensitizer. Fluorescence-guided resection for malignant gliomas has some pitfalls. Moreover, 5-ALA is not merely a fluorescence marker but has potential as a mitochondria-targeting drug for malignant glioma therapy. In this article, we review the literature related to 5-ALA, discuss the pitfalls of fluorescence-guided resection using 5-ALA for malignant gliomas, and describe the application of 5-ALA for malignant glioma therapy with personal opinions.

Characteristics of Bone Destruction in Cranial Vault Lymphoma Compared with Other Skull Tumors.

Cranial vault lymphomas are rare and challenging to diagnose. We present herein two cases of cranial vault lymphoma. The first patient was a 72-year-old woman who presented with a large mass in the parietal bone found incidentally following a head injury. The second patient was a 63-year-old man who presented with an occipital subcutaneous mass associated with visual disturbance and occipital headaches. The diagnosis of a malignant tumor in the second patient was straightforward due to his symptoms and considerable bone destruction, but the first patient was more difficult to diagnose due to a lack of symptoms and only slight bone destruction detected by computed tomography (CT). Both were histophathologically diagnosed with diffuse large B cell lymphoma (DLBCL) in the cranial vault. We also investigated the clinical features, including initial symptoms and patterns of bone destruction, in 23 patients with other types of skull tumors. This comparison showed that cranial vault lymphomas cause large masses on the scalp and lead to characteristic incomplete bone destruction, indicating that cranial bone is destroyed very slowly despite the expanding subcutaneous mass. This feature is unique compared with other benign and malignant skull tumors. In addition, cranial vault lymphoma can be confirmed via bone window CT.

Importance of Finding Embolic Sources for Patients with Embolic Stroke of Undetermined Source.

OBJECTIVE: The concept of embolic stroke of undetermined source refers to cryptogenic strokes caused by either major or minor risks. Although antiplatelet treatments are most often used for secondary prevention of embolic stroke of undetermined source, optimal strategies remain unclear. To determine the ideal treatment strategy for secondary prevention, we investigated embolic sources among patients with embolic stroke of undetermined source. METHODS: The study included 292 consecutive patients (135 men, 157 women; mean age: 74.3 ± 11.6 years) diagnosed with cerebral infarction, 27 of whom were diagnosed with embolic stroke of undetermined source (9.2%; 14 men, 13 women; mean age: 70.7 ± 11.5 years). These 27 patients were examined using contrast-enhanced whole-body computed tomography, transesophageal echocardiography, and Holter electrocardiography. We evaluated whether antiplatelet or anticoagulant treatment was preferred based on the embolic source. RESULTS: Embolic sources among patients with embolic stroke of undetermined source included valve calcification (11.1%), left ventricle diastolic dysfunction (18.5%), cancer-associated stroke (25.9%), covert atrial fibrillation (7.4%), aortic arch atherosclerotic plaques (11.1%), paradoxical embolism (3.7%), and sick sinus syndrome (3.7%). Embolic sources remained unidentified in 5 patients (18.5%). Our analysis revealed that 21 of the 27 patients (77.8%) with embolic stroke of undetermined source required anticoagulant therapy for secondary prevention. CONCLUSION: Although aspirin is the most commonly used antithrombotic drug for embolic stroke of undetermined source, our results suggest that some patients require anticoagulant therapy. Determining embolic sources is important for selecting the appropriate treatment options for this patient population.

Giant Cerebral Aneurysm in a Patient with Cowden Syndrome Treated with Surgical Clipping.

BACKGROUND: Cowden syndrome is characterized by multiple hamartomas and accompanied by a germline mutation of the phosphatase and tensin homolog gene. Cowden syndrome has been described to be associated with vascular anomalies such as arteriovenous malformation and developmental venous anomalies with high frequency. However, the association of cerebral aneurysms with this syndrome has not been reported yet. CASE DESCRIPTION: A 39-year-old Japanese man presented with a subarachnoid hemorrhage due to a ruptured giant fusiform middle cerebral artery aneurysm. We diagnosed him with Cowden syndrome by clinical presentations as outlined in the National Comprehensive Cancer Network's criteria. As the ruptured fusiform aneurysm involved a middle cerebral artery bifurcation, we prepared for extracranial-intracranial bypass surgery. We successfully performed a surgical clipping using multiple tandem clipping techniques and suction decompression techniques. Bypass surgery was not performed as reconstruction of the M2 trunks was successfully completed. CONCLUSIONS: We present this rare case that potentially indicates an association between cerebral aneurysms and Cowden syndrome. Because vascular anomalies are not included in the diagnostic criteria for Cowden syndrome, intracranial vascular anomalies may be underestimated. We therefore recommended a careful search of vascular diseases, including cerebral aneurysms, in cases of Cowden syndrome.

Vessel wall magnetic resonance imaging findings and surgical treatment in nilotinib-associated cerebrovascular disease: A case report.

Nilotinib, a second-generation tyrosine kinase inhibitor, is considered as one of the most effective drugs for the treatment of chronic myeloid leukemia (CML); however, the use of nilotinib has been reported to be associated with vascular adverse events, such as peripheral arterial occlusive disease and ischemic heart disease. Moreover, there are few reports on cerebral vascular disease associated with nilotinib use. We herein describe the case of a 55-year-old male patient with CML, who presented with cerebral infarction and severe cerebrovascular stenosis that developed during nilotinib treatment. The patient was diagnosed with cerebral infarction and severe stenosis of the intracranial arteries associated with nilotinib use. Vessel wall magnetic resonance imaging (VW-MRI) revealed diffuse concentric thickening of the vessel wall, unlike ordinary patterns of atherosclerosis. The patient underwent direct revascularization (superficial temporal artery to middle cerebral artery bypass) and was successfully treated without recurrence. Based on this rare case, VW-MRI may be used to detect the morphological changes of the intracranial arteries that are associated with nilotinib use. Moreover, surgical revascularization may improve the prognosis of nilotinib-associated cerebrovascular diseases, such as severe stenosis or occlusion of the main trunk of the cerebral arteries, that cause brain ischemia.

Intraoperative monitoring of motor-evoked potential for parenchymal brain tumor removal: An analysis of false-negative cases.

Transcranial motor-evoked potential (tc-MEP) monitoring is unreliable for brain tumor removal due to its low sensitivity. According to previous literature, this is because transcranial stimulation seems to reach the deep pyramidal tract beyond the operation point and may thus yield false-negative results, where, although MEP recording is stable, postoperative motor deficits are encountered. Therefore, we aimed to analyze the causes for the false-negative results and investigate whether decreasing the stimulation intensity better reflects the operation point and can improve the sensitivity during parenchymal brain tumor removal. We assessed 122 patients with parenchymal brain and intraventricular tumors, who underwent surgery under tc-MEP monitoring in our hospital between 2011 and 2014. In these patients, the stimulation intensity was fixed at 200 mA. We detected 11 false-negative cases, while the sensitivity of tc-MEP monitoring was 33.9% and the specificity was 99.0%. Between 2015 and 2016, we examined 68 patients with parenchymal brain tumors, in whom the stimulation intensity was reduced to an average of 136.5 mA. Only one case was false-negative, while the sensitivity increased to 83.3% and the specificity was 98.4%. From these results, we conclude that the intensity of tc-MEP stimulation should be minimal to precisely reflect the damage to the operated location. Tc-MEP can be an easy and reliable monitor in brain tumor surgery when used at proper, lower intensity.

Clinical features and surgical management of intracranial meningiomas in the elderly.

Meningioma accounts for ~25% of all primary intracranial neoplasms and the incidence increases with age. Prvios population-based studies demonstrated that the annual incidence of intracranial meningiomas was 1.2-3.1/100,000 population. In particular, the incidence of this disease among the elderly is high. Recently, increased life expectancy and greater use of diagnostic radiological imaging led to an increased incidence in the diagnosis of intracranial meningiomas, both symptomatic and asymptomatic, in the elderly. Thus, neurosurgeons may be increasingly confronted with the management of intracranial meningiomas in the elderly. In practice, it is often difficult for physicians to determine whether traditional surgical resection is the optimal management strategy for intracranial meningiomas in the elderly. However, reported clinical studies about the outcome of surgical resection of intracranial meningiomas in the elderly are limited. Increased risk of mortality and morbidity associated with surgical treatment for intracranial meningiomas in the elderly compared with younger patients have been controversial. In the present study, the clinical features of intracranial meningiomas in 70 consecutive intracranial meningioma patients that underwent surgical treatment at the affiliated hospital of University of Occupational and Environmental Health between 2007 and 2013 were assessed. In addition, patient selection and surgical management of intracranial meningioma in elderly patients was discussed. Preoperative factors, including symptoms, tumor location, tumor size, Karnofsky Performance Scale (KPS) score and American Society of Anesthesiology (ASA) score, and postoperative factors, including pathological diagnosis, tumor proliferation index (Ki-67), resection rate (Simpson grade), length of hospital stay and discharge destination were retrospectively analyzed in patients aged ≥75 years (n=16; elderly group) and <75 years (n=54; younger group). Outcomes were assessed 6 months after surgery. Multivariate logistic regression revealed that tumor resection rate (Simpson grade III-V) was an important predictor of surgical complications (odds ratio, 5.662; 95% confidence interval, 1.323-24.236; P=0.0194). Perioperative morbidity was not correlated with age (>75 years), tumor location, tumor size, KPS score or ASA score. Thus, the present study indicated that age is not associated with surgical outcome in elderly meningioma patients. Regardless of patient age, the decision to perform surgical resection should be made on an individual basis wherein tumor characteristics and the general health of the patient are considered.

Primary intraosseous meningioma in the calvaria: morphological feature changes on magnetic resonance images over several years.

Primary intraosseous meningiomas (PIMs) are rare, and their pathogenesis remains unclear. We report the case of a sizable PIM in the calvaria that progressively enlarged over several years and presented temporal changes in the morphological features on magnetic resonance images. Along with discussing the case, we further emphasize the potential pitfalls of diagnosing a PIM in the calvaria.

Pilocytic astrocytoma presenting with atypical features on magnetic resonance imaging.

Pilocytic astrocytoma, which is classified as a grade I astrocytic tumor by the World Health Organization, is the most common type of glioma in children and young adults. Pilocytic astrocytoma generally appears as a well-circumscribed, contrast-enhancing lesion, frequently with cystic components on magnetic resonance imaging (MRI). However, it has been reported that the MRI appearance of pilocytic astrocytoma may be similar to that of high-grade gliomas in some cases. We here report on 6 cases of pilocytic astrocytoma with atypical MRI findings, including small cyst formation, heterogeneously enhancing tumor nodules, irregularly enhancing tumor nodules, and enhancing tumor nodules with internal hemorrhage. All tumors were successfully resected, and the histological diagnoses were pilocytic astrocytoma. When the tumor is located near a cerebral cistern or ventricle, the risk of leptomeningeal dissemination is increased. Furthermore, partial resection has also been associated with a higher risk of recurrence and leptomeningeal dissemination. To date, all but one patient are alive and recurrence-free. Because the preoperative diagnosis influences the decision on the extent of resection and because of the high risk of leptomeningeal dissemination associated with these tumors, careful and correct diagnosis by MRI is important.

Pitfalls of conservative treatments of multiple probable cerebral cavernous malformations (CCMs): clinicopathological features of CCMs coexisting with vasculogenic mimicry in an anaplastic oligodendroglioma.

Developments in magnetic resonance imaging (MRI) techniques have dramatically increased the detection of cerebral cavernous malformations (CCMs). Conservative treatment is often recommended for asymptomatic cases. However, CCMs occasionally harbor malignant gliomas. Here, we describe a rare case of multiple probable CCMs and an anaplastic oligodendroglioma (AO) showing vasculogenic mimicry (VM) and discuss the potential pitfalls of conservative treatments. A 42-year-old otherwise healthy woman presented with generalized seizures. Magnetic resonance imaging (MRI) revealed multiple parenchymal hypointensities, particularly in the right frontal lobe, with hyperintensity on fluid-attenuated inversion recovery (FLAIR) images. The patient was diagnosed with multiple probable CCMs, and conservative treatment was administered. However, follow-up MRI showed a slightly enlarged hyperintense area in the right frontal lobe. The patient then underwent surgery; histological diagnosis was CCMs and AO with VM. The patient subsequently underwent radiotherapy and chemotherapy. No neurological deficits or tumor recurrence were evident 21 months after surgery. We present this rare case and emphasize the possibility of the coexistence of malignant gliomas with CCMs. Close observation with MRI is essential in cases of multiple probable CCMs, and a histological confirmation should be considered in cases showing any enlargement of hyperintensity on FLAIR images.

Intratumoral hemorrhage because of primary spinal mixed germ cell tumor presenting with atypical radiological features in an adult.

BACKGROUND CONTEXT: Germ cell tumors are known to arise in the central nervous system, usually in the intracranial regions. However, primary spinal mixed germ cell tumors are extremely rare. PURPOSE: This is the first reported case of intratumoral hemorrhage because of a primary spinal mixed germ cell tumor consisting of germinoma and immature teratoma in the conus medullaris of an adult patient that presented with rapid changes on magnetic resonance image (MRI). We report this rare case and discuss the clinical manifestations of an intramedullary spinal mixed germ cell tumor in adult. STUDY DESIGN: A case report. METHODS: A 42-year-old woman experienced buttock numbness, and a spinal cord tumor was observed on the conus medullaris on MRI. The patient was scheduled for an operation in 1 month, but she developed sudden-onset neurologic deterioration. Rapid progression of the tumor was observed on follow-up MRI. The tumor was removed by emergency surgery and was identified as a primary mixed germinoma and immature teratoma. RESULTS: The patient received adjuvant chemotherapy and radiotherapy after gross total resection. The neurologic deficit of the patient was relieved, and recurrence of the tumor was not observed 26 months after the surgery. CONCLUSIONS: We present this rare case and emphasize the necessity of precise diagnosis and early treatment of primary spinal germ cell tumor. Close observation on MRI is required after surgery, and adjuvant chemotherapy and radiotherapy should be considered according to the pathologic features.

[A case of accidental hypothermia caused by cervical spinal cord injury].

Accidental hypothermia is the state in which body temperature falls due for exposure to a chilly environment. In accidental hypothermia, the mortality rate is higher the lower the body temperature. We report a case of a consciousness disorder and severe hypothermia, with a body temperature below 28 degrees C, in which it later became clear that a cervical spinal cord injury had been caused by a small external force. A 70-year-old woman was transported to our hospital in an ambulance for consciousness disturbance and severe hypothermia. At the time of arrival, her rectal temperature was 26.2 degrees C. We promptly performed rewarming. Her consciousness level became clear, but paralysis and diminished sensation were observed below the C5 domain. We suspected cervical spinal cord injury and performed cervical magnetic resonance imaging. She was diagnosed as having C5 cervical spinal cord injury. When there is a consciousness disorder due to accidental hypothermia, it might not be possible to evaluate the neurological value of the cervical spinal cord injury correctly. The presence of cervical spinal cord injury should be considered when patients have a decreased consciousness level due to hypothermia.

Spontaneous hemorrhage from orbital cavernous hemangioma resulting in sudden onset of ophthalmopathy in an adult--case report.

A 61-year-old woman presented with a very rare case of spontaneous bleeding from an orbital cavernous hemangioma manifesting as sudden onset of ophthalmic pain, proptosis, diplopia, and nausea. Magnetic resonance (MR) imaging and computed tomography (CT) revealed an intraconal, well-demarcated cystic mass with hemorrhage. The mass was immediately removed through a transcranial approach. Histological examination showed that the mass was a cavernous hemangioma. Ophthalmopathy was resolved by surgery. Orbital cavernous hemangioma is very common in adults, but spontaneous bleeding is extremely rare relative to intracranial cavernous hemangiomas. This rare case emphasizes the importance of careful neuroimaging evaluation with MR imaging and CT for diagnosing orbital cavernous hemangioma associated with spontaneous bleeding.

Preoperative radiological evaluation and surgical strategy for the preservation of visual acuity in patients with skull base meningiomas--two case reports.

Two women aged 48 and 73 years, respectively, presented with unilateral visual disturbance. On admission, magnetic resonance imaging (MRI) showed an extraaxial mass in the parasellar region. Contrast-enhanced fast imaging with steady-state acquisition (CE-FIESTA) showed that the optic nerves were compressed and encased by the tumors. At an early stage of surgery, we performed decompression of the optic nerves to avoid optic nerve injury. Both the patients were relieved of visual disturbances without any postoperative neurological deficit. In conclusion, CE-FIESTA is a useful diagnostic tool for preoperative evaluation of the optic nerves in patients with skull base meningiomas. Decompression of the optic nerves should be performed at an early stage of surgery in meningioma patients presenting with visual disturbance.

Surgical treatment for a ruptured true posterior communicating artery aneurysm arising on the fetal-type posterior communicating artery--two case reports and review of the literature.

Only a small number of aneurysms arising on the posterior communicating artery itself (true Pcom aneurysm) have been reported. We report two cases of ruptured true Pcom aneurysms with some characteristic features of true Pcom aneurysm. A 43 year old man suffering from subarachnoid hemorrhage (SAH) had an aneurysm arising on the fetal-type Pcom artery itself, and underwent surgery for clipping. Most of the aneurysm was buried in the temporal lobe, so retraction of the temporal lobe was mandatory. During the retraction, premature rupture was encountered. After tentative dome clipping and the control of bleeding, complete clipping was achieved. Another patient, a 71 year old woman presenting with consciousness disturbance due to SAH, had an aneurysm on the fetal-type Pcom artery itself, and underwent surgery for clipping. It has been generally considered that hemodynamic factor plays an important role in the formation, the growth, and the rupture of the cerebral aneurysm. This factor is especially significant in true Pcom aneurysm formation and rupture. According to the literature, a combination of fetal type Pcom and formation of the true Pcom aneurysm has been reported in most cases (81.8%). Most of the aneurysm can be buried in the temporal lobe, and the retraction of the temporal lobe during the dissection of the neck would be necessary, which causes premature rupture of the true Pcom aneurysm. In the surgery for a true Pcom aneurysm, we should be aware of possible premature rupture when temporal lobe retraction is necessary.