Feasibility of a modified Atkins diet in glioma patients during radiation and its effect on radiation sensitization.

Background: Gliomas are the most dreaded primary brain tumour because of their dismal cure rates. Ketogenic-type diets (kds) are high-fat, low-protein, and low-carbohydrate diets; the modified Atkins diet (mad) is a less-stringent version of a kd that still generates serum ketones in patients. The purpose of the present study was to retrospectively examine the feasibility of attaining ketosis and the safety of the mad in patients undergoing radiation and chemotherapy treatment for glioma. The rate of pseudoprogression (psp) after treatment was also assessed as a marker of radiation sensitization. To our knowledge, this dataset is the largest published relating to patients with glioma undergoing kd during radiation and chemotherapy. Methods: We retrospectively studied 29 patients with grades ii-iv astrocytoma following the mad during standard radiation and chemotherapy. Feasibility of attaining ketosis was assessed though levels of beta hydroxybutyrate in blood. Pre- and post-radiation magnetic resonance images were evaluated for psp by a neuroradiologist blinded to patient data. Results: In the 29 patients who started the mad during radiation, ketosis was achieved in all 29 (100%). No serious adverse events occurred secondary to the mad. Of those 29 patients, 19 had glioblastoma multiforme. Of the latter 19 patients, 11 (58%) showed psp after mad and radiation and temozolomide therapy. Conclusions: A modified Atkins diet is feasible and safe for glioma patients during radiation and chemotherapy treatment. The mad and resulting ketosis could play a role as a radiation sensitizer.

Cerebral venous thrombus signal intensity and susceptibility effects on gradient recalled-echo MR imaging.

BACKGROUND AND PURPOSE: Cerebral venous thrombus (CVT) signal intensity is variable on MR imaging, and the appearance of CVT on gradient recalled-echo (GRE) sequences has been incompletely assessed. This study was performed to evaluate the GRE imaging appearance of CVT in different stages of thrombus evolution and its relationship to signal intensity on other MR pulse sequences. MATERIALS AND METHODS: The clinical and MR imaging findings in 18 patients with CVT and GRE imaging were reviewed. Sixty-nine thrombosed venous segments were evaluated, and the signal intensity of thrombus relative to gray matter was determined. The degree of thrombus susceptibility effect (SE) was assessed and related to time of imaging after onset of symptoms (clinical thrombus age) and appearance on other pulse sequences. Segments were classified as SE+ (demonstrating susceptibility effect) or SE- (no susceptibility effect). RESULTS: Thirty-six venous segments exhibited visible SE. SE+ segments had a clinical thrombus age that was less than that in SE- segments (8.1 versus 24.6 days, P=.003). Sixty-three percent (23/36) of SE+ segments exhibited hypointensity on T2-weighted images (T2WI) versus 12% (4/33) of SE- segments (P<.001). Twenty-nine of 32 (90.6%) segments with clinical thrombus age of 0-7 days were SE+, versus 7 of 30 (23.3%) segments with a thrombus age of 8 days or greater. CONCLUSION: SEs from CVT can be detected with GRE imaging and are most prevalent in patients with hypointense thrombus on T2WI within 7 days after the symptom onset. This correlates with the paramagnetic effects of deoxyhemoglobin in acute stage thrombus. GRE imaging may be useful in detecting thrombus in this stage when difficult to detect on other pulse sequences.

Cerebrovascular trauma.

Cerebrovascular trauma includes a wide variety of injuries, including dissections, traumatic aneurysms, arteriovenous fistulas, and vascular occlusions. These entities, which are often underdiagnosed, can produce devastating neurologic complications. This article reviews the clinical and radiographic presentations of vascular trauma to increase awareness of these injuries and improve our ability to detect and treat them.

Glioma resection in a shared-resource magnetic resonance operating room after optimal image-guided frameless stereotactic resection.

OBJECTIVE: We describe a shared-resource intraoperative magnetic resonance imaging (MRI) design that allocates time for both surgical procedures and routine diagnostic imaging. We investigated the safety and efficacy of this design as applied to the detection of residual glioma immediately after an optimal image-guided frameless stereotactic resection (IGFSR). METHODS: Based on the twin operating rooms (ORs) concept, we installed a commercially available Hitachi AIRIS II, 0.3-tesla, vertical field, open MRI unit in its own specially designed OR (designated the magnetic resonance OR) immediately adjacent to a conventional neurosurgical OR. Between May 1998 and October 1999, this facility was used for both routine diagnostic imaging (969 diagnostic scans) and surgical procedures (50 craniotomies for tumor resection, 27 transsphenoidal explorations, and 5 biopsies). Our study group, from which prospective data were collected, consisted of 40 of these patients who had glioma (World Health Organization Grades II-IV). These 40 patients first underwent optimal IGFSRs in the adjacent conventional OR, where resection continued until the surgeon believed that all of the accessible tumor had been removed. Patients were then transferred to the magnetic resonance OR to check the completeness of the resection. If accessible residual tumor was observed, then a biopsy and an additional resection were performed. To validate intraoperative MRI findings, early postoperative MRI using a 1.5-tesla magnet was performed. RESULTS: Intraoperative images that were suitable for interpretation were obtained for all 40 patients after optimal IGFSRs. In 19 patients (47%), intraoperative MRI studies confirmed that adequate resection had been achieved after IGFSR alone. Intraoperative MRI studies showed accessible residual tumors in the remaining 21 patients (53%), all of whom underwent additional resections. Early postoperative MRI studies were obtained in 39 patients, confirming that the desired final extent of resection had been achieved in all of these patients. One patient developed a superficial wound infection, and no hazardous equipment or instrumentation problems occurred. CONCLUSION: Use of an intraoperative MRI facility that permits both diagnostic imaging and surgical procedures is safe and may represent a more cost-effective approach than dedicated intraoperative units for some hospital centers. Although we clearly demonstrate an improvement in volumetric glioma resection as compared with IGFSR alone, further study is required to determine the impact of this approach on patient survival.

Intraoperative magnetic resonance imaging to determine the extent of resection of pituitary macroadenomas during transsphenoidal microsurgery.

OBJECTIVE: Well-established surgical goals for pituitary macroadenomas include gross total resection for noninvasive tumors and debulking with optic chiasm decompression for invasive tumors. In this report, we examine the safety, reliability, and outcome of intraoperative magnetic resonance imaging (iMRI) used to assess the extent of resection, and thus the achievement of preoperative surgical goals, during transsphenoidal microneurosurgery. METHODS: Our magnetic resonance operating room contains a Hitachi AIRIS II 0.3-T, vertical-field open magnet (Hitachi Medical Systems America, Inc., Twinsburg, OH). A motorized scanner tabletop moves the patient between the imaging and operative positions. For transsphenoidal surgery, the patient is positioned directly on the scanner tabletop so that the surgical field is located between 1.2 and 1.6 m from the magnet isocenter. At this location, the magnetic field strength is low (<20 G), thus permitting the use of many conventional surgical instruments. Thirty consecutive patients with pituitary macroadenomas underwent tumor resection in our magnetic resonance operating room by use of a standard transsphenoidal approach. After initial resection, the patient was advanced into the scanner for imaging. If residual tumor was demonstrated and deemed surgically accessible, the patient underwent immediate re-exploration. RESULTS: iMRI was performed successfully in all 30 patients. In one patient, iMRI was used to clarify the significance of hemorrhage from the sellar region and resulted in immediate conversion of the procedure to a craniotomy. In the remaining 29 patients, initial iMRI demonstrated that the endpoint for extent of resection had been achieved in only 10 patients (34%) after an initial resection attempt, whereas 19 patients (66%) still had unacceptable residual tumor. All 19 of these latter patients underwent re-exploration. Ultimately, re-exploration resulted in the achievement of the planned endpoint for extent of resection in all of the 29 completed transsphenoidal explorations. Operative time was extended in all cases by at least 20 minutes. CONCLUSION: iMRI can be used to safely, reliably, and objectively assess the extent of resection of pituitary macroadenomas during the transsphenoidal approach. The surgeon is frequently surprised by the extent of residual tumor after an initial resection attempt and finds the intraoperative images useful for guiding further resection.

Utility, safety, and accuracy of intraoperative angiography in the surgical treatment of aneurysms and arteriovenous malformations.

BACKGROUND AND PURPOSE: The role of intraoperative angiography in the treatment of neurovascular lesions has remained extremely controversial. We retrospectively reviewed the utility, safety, and accuracy of intraoperative angiography to ascertain its effect on the treatment of patients with neurovascular lesions. METHODS: We reviewed the results of intraoperative angiography in 91 patients treated surgically for intracranial aneurysms and in 98 patients treated surgically for arteriovenous malformations (AVMs). All treatments were completed at two major teaching hospitals between October 1987 and March 1995. RESULTS: The initial angiographic findings caused the surgical procedure to be modified in 24 (26%) of the patients with aneurysms and in 28 (29%) of the patients with AVMs. Analysis of the final angiographic sequence showed residual lesions in nine (10%) of the aneurysm cases and in eight (8%) of the AVM cases. The imperfect angiographic results were deemed acceptable because there was either evidence of collateral flow when the parent vessel was occluded or the risk of further surgical modification was considered more dangerous than the abnormality itself. Seven patients suffered complications, of which only one had permanent neurologic sequelae: a CNS complication rate of 0.5%. Comparison of the intraoperative angiographic findings with those of postoperative studies revealed four false-negative results (5.2%). CONCLUSION: Intraoperative angiography is an important component in the treatment of patients with intracranial vascular lesions. It is effective and can be carried out with low risk in this patient population.

Routine CT evaluation of acute stroke.

Although new imaging techniques such as MR perfusion/diffusion and xenon CT have shown considerable promise in the detection of early brain ischemia, noncontrast CT remains the primary imaging test for the evaluation of acute stroke. It is fast, reliable, readily available, and continues to be used for all major stroke therapy trials. Despite its limitations, CT is an accurate method of screening patients prior to thrombolytic therapy.

Corpus callosal changes associated with hydrocephalus: a report of two cases.

OBJECTIVE AND IMPORTANCE: Focal or diffuse corpus callosal changes can occur in patients with active hydrocephalus who undergo shunting procedures. The neural compression caused by active hydrocephalus and the conditions that follow ventricular shunting may contribute to the development of these changes. CLINICAL PRESENTATION: Two patients who underwent successful shunting for hydrocephalus subsequently developed thickening and diffuse signal changes in the corpus callosum, which were revealed by magnetic resonance imaging. The abnormal signal intensity extended laterally and linearly along the callosal fiber tracts and was not associated with mass effect. These changes persisted despite clinical improvement after the shunts were implanted. INTERVENTION: Detailed neuropsychological testing showed no evidence of residual cognitive impairment or any interruption of the interhemispheric transfer of information. It has been proposed that the impingement of the corpus callosum by the rigid falx may contribute to symptomatic hydrocephalus. Impingement may cause partial hemispheric disconnection, resulting from callosal axonal dysfunction. Our patients showed radiographic evidence of dramatic changes within the corpus callosum after ventricular shunting, consistent with a transcallosal demyelinating process. Patients demonstrated neither clinical nor neuropsychological evidence of callosal disconnection, even though the callosal changes persisted. In these two patients, it is reasonable to assume that the relative sparing of the splenium accounts for the lack of neuropsychological deficits. CONCLUSION: Based on our findings, conservative management, rather than a stereotactic biopsy or other forms of intervention, seems reasonable when these characteristic changes of the callosum are noted by magnetic resonance imaging after a shunt for hydrocephalus has been implanted in the patient.

Cervical myelopathy associated with intracranial dural arteriovenous fistula: MR findings before and after treatment.

The MR findings in three patients with intracranial dural arteriovenous fistula associated with cervical myelopathy are described. The MR appearance of an enlarged cord with associated abnormal signal and enhancement is nonspecific and can simulate tumor, demyelination, and inflammation. Enlarged perimedullary vessels may not always be identifiable, but if present, should suggest the presence of an arteriovenous fistula.

Angiography in the evaluation of head and neck trauma.

Cerebrovascular trauma is a heterogeneous group of injuries including arterial dissections, traumatic aneurysms, arteriovenous fistulas, and venous occlusions. Detection of vascular trauma may be difficult because of variations in clinical presentation; however, in recent years, increased awareness and understanding of these injuries has improved the ability to detect and subsequently treat many lesions. Despite advances in other imaging modalities, angiography remains the primary radiographic tool used in the evaluation of traumatic vascular lesions.

Evaluation of prevertebral muscle invasion by squamous cell carcinoma. Can computed tomography replace open neck exploration?

OBJECTIVE: To compare computed tomography (CT) with open neck exploration in determining prevertebral invasion by squamous cell carcinoma of the oropharynx or hypopharynx. DESIGN: Retrospective analysis using the findings at open neck exploration and results of histopathologic studies as the criterion standards. SETTING: Tertiary care referral center. PATIENTS: Twenty-nine of 40 patients with advanced squamous cell carcinoma of the oropharynx or hypopharynx treated between January 1, 1986, and December 31, 1994, were selected for analysis based on CT findings of posterolateral extension of the primary tumor placing the prevertebral muscle (PVM) at risk. All study patients had no previous therapy and underwent neck exploration to determine resectability. RESULTS: Overall accuracy of CT in predicting PVM status was 55.2%. The sensitivity of preoperative CT for PVM invasion was 50%; the specificity was 61%. Using an estimate of 21% for the prevalence of PVM invasion, the predictive value of a positive CT scan was 0.254 and the predictive value of a negative CT scan was 0.821. Open neck exploration correctly predicted PVM status in all cases. CONCLUSIONS: Open neck exploration is superior to CT to evaluate possible PVM invasion by squamous cell carcinoma of the oropharynx or hypopharynx. The predictive value of a negative CT scan for PVM invasion is high, so it may be useful in treatment planning. Patients with advanced squamous cell carcinoma of the oropharynx or hypopharynx at risk for PVM invasion who are otherwise surgical candidates should be considered for open neck exploration to determine resectability most accurately.

Endovascular therapy of intractable epistaxis complicated by carotid artery occlusive disease.

Three cases of intractable spontaneous posterior epistaxis refractory to nasal packing and complicated by ipsilateral carotid artery occlusive disease were successfully treated with internal maxillary artery occlusion with microcoils. There were no complications and no recurrent episodes of epistaxis at a mean follow-up of 12 months. The presence of ipsilateral carotid artery disease requires modification of standard distal internal maxillary artery embolization because of the recruitment of external carotid to internal carotid and external carotid to ophthalmic artery collateral pathways, with subsequent risk of particle embolization of these arterial distributions. Proximal internal maxillary artery microcoil embolization eliminates this risk and is equivalent to surgical internal maxillary artery ligation. This procedure also provides additional information about the internal carotid artery collateral circulation.