Influence of magnetic source imaging for planning intracranial EEG in epilepsy.

BACKGROUND: Magnetic source imaging (MSI) is used routinely in epilepsy presurgical evaluation and in mapping eloquent cortex for surgery. Despite increasing use, the diagnostic yield of MSI is uncertain, with reports varying from 5% to 35%. To add benefit, a diagnostic technique should influence decisions made from other tests, and that influence should yield better outcomes. We report preliminary results of an ongoing, long-term clinical study in epilepsy, where MSI changed surgical decisions. METHODS: We determined whether MSI changed the surgical decision in a prospective, blinded, crossover-controlled, single-treatment, observational case series. Sixty-nine sequential patients diagnosed with partial epilepsy of suspected neocortical origin had video-EEG and imaging. All met criteria for intracranial EEG (ICEEG). At a surgical conference, a decision was made before and after presentation of MSI. Cases where MSI altered the decision were noted. RESULTS: MSI gave nonredundant information in 23 patients (33%). MSI added ICEEG electrodes in 9 (13%) and changed the surgical decision in another 14 (20%). Based on MSI, 16 patients (23%) were scheduled for different ICEEG coverage. Twenty-eight have gone to ICEEG, 29 to resection, and 14 to vagal nerve stimulation, including 17 where MSI changed the decision. Additional electrodes in 4 patients covered the correct: hemisphere in 3, lobe in 3, and sublobar ictal onset zone in 1. MSI avoided contralateral electrodes in 2, who both localized on ICEEG. MSI added information to ICEEG in 1. CONCLUSION: Magnetic source imaging (MSI) provided nonredundant information in 33% of patients. In those who have undergone surgery to date, MSI added useful information that changed treatment in 6 (9%), without increasing complications. MSI has benefited 21% who have gone to surgery.

Volumetric multishot echo-planar spectroscopic imaging.

Rapid volumetric magnetic resonance spectroscopic imaging (MRSI) is potentially of great relevance to the diagnosis and treatment of focal cerebral diseases such as cancer and epilepsy. A strategy for volumetric multishot echo-planar spectroscopic imaging (MEPSI) is described which allows whole-brain metabolite mapping in approximately 20 min. A multishot trajectory is used in both the spatial and temporal domains which reduces the accumulated phase during each echo train and tolerates conventional Fourier reconstruction without regridding. Also described is a generalized correction for phase discontinuities arising from the multishot acquisition of the time domain, which is independent of the spatial k-space trajectory and is therefore also applicable to multishot spiral MRSI. Whole-brain, lipid-suppressed MEPSI data were acquired from five normal subjects. The mean signal-to-noise ratios (SNRs) (+/-SE) for the n-acetylaspartate (NAA), choline (Cho), and creatine (Cr) maps across all subjects were 21.3 +/- 1.8, 11.7 +/- 0.6, and 9.2 +/- 0.6, respectively, with a computed voxel size of 2.33 ml.

Dipole localization of human induced focal afterdischarge seizure in simultaneous magnetoencephalography and electrocorticography.

Localizations were compared for the same human seizure between simultaneously measured MEG and iEEG, which were both co-registered to MRI. The whole-cortex neuromagnetometer localized a dipole in a sphere phantom, co-registered to the MEG sensor array, with an error of 1.4 mm. A focal afterdischarge seizure was induced in a patient with partial epilepsy, by stimulation at a subdural electrocorticography (ECoG) electrode with a known location, which was co-registered to the MRI and to the MEG sensor array. The simultaneous MEG and ECoG during the 30-second seizure was measured and analyzed using the single, moving dipole model, which is the localization model used clinically. The dipole localizations from simultaneous whole cortex 68-channel MEG and 64-channel ECoG were then compared for the repetitive spiking at six different times during the seizure. There were two main regions of MEG and ECoG activity. The locations of these regions were confirmed by determining the location clusters of 8,000 dipoles on ECoG at consecutive time points during the seizure. The mean distances between the stimulated electrode location versus the dipole location of the MEG and versus the dipole location of the ECoG were each about one (1) centimeter. The mean distance between the dipole locations of the MEG versus the dipole locations of the ECoG was about 2 cm. These errors were compared to errors of MEG and ECoG reported previously for phantoms and for somatosensory evoked responses (SER) in patients. Comparing the findings from the present study to those from prior studies, there appeared to be the expected stepwise increase in mean localization error progressing from the phantom, to the SER, to the seizure.

Efficacy of proton magnetic resonance spectroscopy in clinical decision making for patients with suspected malignant brain tumors.

We wished to determine the utility of single voxel proton (1H) magnetic resonance spectroscopy (MRS) when used as an alternative or adjunct to brain biopsy in patients harboring lesions suggestive of brain tumors identified by MRI scan. Fifteen patients (age 7-58 years) with MRI scans and clinical histories suggestive of primary brain tumors underwent single voxel 1H-MRS. MRS (16 regions of interest in 15 patients) was used to aid in differentiation between tumor and other pathologies such as stroke or demyelinating plaque (n = 6), radiation necrosis (n = 5), or edema (n = 5). Spectra were quantified to determine absolute molar values of N-acetyl aspartate (NAA), choline (Cho), creatine (Cr), lactate (LAC), and myo-inositol (mI), metabolite ratios relative to Cr were calculated, and spectra were interpreted based on metabolite ratios. Subsequent clinical management was based on MRS interpretation, and patients were then followed to determine if MRS interpretation accurately predicted clinical outcome or surgical findings. Mean follow-up was 12.5 months (range 3-28 months). MRS suggested the presence of recurrent tumor in 7 cases, all of which were subsequently 'confirmed' by tumor resection (n = 4) or disease progression (n = 3). MRS suggested the presence of new tumor in 1 case, subsequently confirmed by surgical resection. MRS suggested the presence of necrosis in 3 patients; all 3 remained radiographically stable during the follow-up period, and one was confirmed by stereotactic biopsy. MRS suggested non-neoplastic lesions in 4 cases, 3 of whom were followed until radiographic resolution of lesions and one of which was confirmed as a pyogenic abscess via stereotactic aspiration. Overall, MRS accurately predicted the pathological nature and clinical outcome of lesions in 15/16 (96%) situations, influenced clinical decision making in 12 cases, and altered surgery planning in 7 patients. In appropriate circumstances MRS can reduce the need for biopsy, and provide an important guide for clinical decision-making in difficult cases.

Fatal cyst formation after fetal mesencephalic allograft transplant for Parkinson's disease.

OBJECT: In recent years, fetal mesencephalic tissue transplant for the treatment of Parkinson's disease (PD) has been demonstrated to hold promise, but potential complications related to growth of allograft tissue have not been well described. This report explores the development and possible causation of a fatal cyst arising from a fetal transplant in the brain. METHODS: The authors report the case of a 52-year-old woman who underwent bilateral putamenal fetal mesencephalic allograft transplant for PD at another hospital. Twenty-three months later she presented to the authors' institution in a coma. Admission computerized tomography and magnetic resonance (MR) studies revealed a contrast-enhancing mural nodule and associated large cyst arising from the left putamen and causing brainstem compression. Despite surgical decompression of the cyst, the patient did not regain consciousness. Biopsy and autopsy specimens were obtained, along with an analysis of the cyst fluid. Genotyping of the nodule and the patient's peripheral lymphocytes by using polymerase chain reaction-based microsatellite analysis was also performed. Biopsy samples and autopsy histopathological studies showed inflammatory cells, hemosiderin-laden macrophages, and astrocytosis. Scattered neurons and multiple rests of choroid plexus were also noted. The cyst had a thin wall and contained liquid that was identical in composition to cerebrospinal fluid (CSF). Genotyping demonstrated the presence of alleles in the nodule DNA that were not present in lymphocytic DNA, indicating that the nodule contained allograft tissue. CONCLUSIONS: The authors hypothesize that the choroid plexus tissue contained in the allograft resulted in CSF production and cyst formation at the transplant site, ultimately leading to the patient's herniation syndrome. The clinical history and large size of the mural nodule indicate slow growth of this allograft site and cyst over time. This case demonstrates that unusual patterns of tissue growth can occur in the brain after fetal tissue transplant and emphasizes the need for long-term monitoring of posttransplant patients by means of MR imaging. Cell sorting should be considered to ensure transplant of pure neuronal and astroglial populations.

Venous angiography is needed to interpret inferior petrosal sinus and cavernous sinus sampling data for lateralizing adrenocorticotropin-secreting adenomas.

Bilateral simultaneous venous sampling of ACTH from the inferior petrosal sinus is a reliable test for diagnosing Cushing's disease, but is not reliable for lateralizing ACTH-secreting pituitary adenomas. We reviewed 23 consecutive patients with Cushing's disease who underwent venous angiography of the cavernous and inferior petrosal sinuses followed by bilateral simultaneous venous sampling of ACTH in the inferior petrosal and cavernous sinuses. Venous drainage was bilaterally symmetric in 14 patients (61%) and asymmetric in 9 (39%). The most common asymmetric pattern (6 patients) was for blood from both cavernous sinuses to drain into the right inferior petrosal sinus, with no significant drainage into the left. Cavernous sinus sampling in 21 patients correctly lateralized the tumor in 12 cases of symmetric venous drainage, but in only 3 cases of asymmetric drainage. Inferior petrosal sinus sampling in all 23 patients correctly lateralized the tumor in 12 cases of symmetric drainage, but in only four cases of asymmetric drainage. Overall, venous sampling correctly lateralized 70% of the tumors. Incorrect lateralization in cases of asymmetric venous drainage is probably attributable to shunting of blood toward the side of dominant venous drainage. Our findings illustrate the need for venography in all patients undergoing venous sampling of ACTH because an understanding of the venous drainage patterns is essential to correctly interpret venous sampling data and warn physicians that the lateralization data may be incorrect or unreliable.

Complications of anterior skull base surgery.

The complications associated with anterior skull base surgery were reviewed in 49 consecutive patients treated between November 1986 and August 1993. All procedures involved a combined otolaryngologic and neurosurgical approach, and the senior otolaryngologist was the same. Fifty-two procedures were completed; 37 for malignant disease and 15 for benign disease. Twenty-one of the 52 procedures had postoperative complications, a 40% complication rate. One postoperative death occurred from a myocardial infarction, for a 2% mortality rate. Infections complications were the most common, occurring in 19% of cases. The one case of meningitis responded to antibiotic therapy, without neurologic sequelae. Seven cerebrospinal fluid leaks occurred (13%); five resolved with conservative management, and two required reoperation. There was no significant difference between complication rates for patients with previous craniotomy, radiation therapy, or chemotherany compared with those with no prior therapy (p > .05). More complications occurred in patients with malignant disease than in those with benign disease (46% vs 27%), but this was not statistically significant (p > .05). Anterior and anterolateral skull base resection as part of a multidisciplinary approach to diseases of this region may provide improved palliation and may offer possible improved survival with acceptable surgical mortality. Although only 6% of patients were left with permanent neurologic sequelse in this series, the risks of serious complications are considerable.

Improved management of multiple brain abscesses: a combined surgical and medical approach.

Bacterial brain abscesses occur in approximately 1500 to 2500 patients each year in the United States. Multiple abscesses have been noted in 10 to 50% of these patients. The goal of this study was to better define the roles of surgery and medical management in patients harboring multiple brain abscesses and to develop an algorithmic approach to the treatment of these complex patients. Between 1976 and 1992, 16 patients with multiple brain abscesses were treated by a single physician (M.L.R.). The ages of the patients ranged from 1.5 to 73 years (median, 47 yr). In all patients, a diagnosis of multiple abscesses was made by computed tomography (15 patients) or magnetic resonance imaging (1 patient) brain scans. The number of abscesses per patient ranged from 2 to 30, and the abscesses were located in all regions of the brain. Thirteen received a combination of antibiotics and surgical drainage, and three received antibiotics only. Surgery was performed on abscesses larger than 2.5 cm or on those situated in critical areas of the brain or causing significant mass effect. Excision and open aspiration via craniotomy and stereotactic aspiration were analyzed on the basis of the location of the lesion and infecting organism. Any abscess that enlarged after 2 weeks of antibiotics or that failed to shrink after 3 to 4 weeks of antibiotics was again aspirated or excised. Forty-three surgical procedures were performed in 13 patients, and 8 (62%) of the patients operated on required more than one surgical procedure. No significant morbidity was observed in any of the surgical procedures. Antibiotics were administered intravenously for an average of 6 to 8 weeks and were adjusted according to organism type and sensitivity to antibiotics. One patient (6%) died, and the remaining 15 patients had resolution of all abscesses and good neurological recovery within 6 months. On the basis of these results, we propose a combined surgical and medical approach to the treatment of patients with multiple brain abscesses. We recommend the aggressive surgical drainage of all abscesses larger than 2.5 cm in diameter, combined with 6 to 8 weeks of intravenous antibiotics. Biweekly computed tomography or magnetic resonance imaging is necessary to closely monitor patients for evidence of abscess growth or failure to resolve despite antibiotics, prompting another operation. The application of this combined approach should yield cure rates of more than 90% in patients with multiple brain abscesses, a result similar to that expected when treating patients with solitary lesions.

The "filum intermedium" sign: focal in utero spinal cord infarct and extraspinal thecal sac. Case report.

This report describes the unique case of a child born with paraplegia and a neurogenic bladder who was found to have a dysplastic, nonossified T-12 vertebral body, midline fusion of the T-12 neural arches, obliteration of the spinal canal at T-12, and an extraspinal thecal sac in the T11-L1 region. Neural tissue was focally absent from T9-12, but neural structures above and below were preserved. Narrowing of the thecal sac on myelograms and sagittal magnetic resonance images signifies in utero focal infarction of the spinal cord after neurulation but before formation of the posterior half of the spinal canal. The infarction resulted in severe focal narrowing of the thecal sac from T10-L1, resembling a premature and duplicated filum terminale; to denote the radiographic appearance of these anomalies, the authors have coined the term "filum intermedium" sign. The extremely unusual radiographic findings in this child illustrate the important interactions between neural tube, neural crest, and somite in the development of the spinal cord and spinal column. Correlation of the radiographic findings with the embryological differentiation and migration of these structures suggests that the spinal anomalies were caused by a focal insult, probably vascular in origin, occurring between the sixth and eighth weeks of gestation. The identification of a focally narrowed thecal sac and spinal cord (the "filum intermedium" sign) localizes the time of the insult to between the first and third month of gestation, and therefore is a useful marker in understanding developmental malformation of the spinal cord.

Treatment options and prognosis for multicentric juvenile pilocytic astrocytoma.

Little is known about the risk of developing multicentric disease in patients with juvenile pilocytic astrocytoma (JPA), and even less about its prognosis. Only five cases have been reported. Between 1986 and 1992, the authors treated 90 patients with either primary or recurrent JPA, 11 of whom developed multicentric spread. Ten patients had primary tumors in the hypothalamic region, eight were under 4 years of age at initial diagnosis, all had initially undergone a subtotal resection or biopsy, and 10 received postoperative multiagent chemotherapy or irradiation for residual disease. Multicentric spread was discovered immediately to 108 months after initial diagnosis; nine patients were asymptomatic at the time. Most patients received chemotherapy for the multicentric disease, which was found throughout the craniospinal axis. During 21 to 148 months of follow-up monitoring, seven patients had stabilization or regression of multicentric disease and four died. Patients with hypothalamic region tumors were 23 times more likely to develop multicentric spread than were those with primary tumors located elsewhere (p < 0.001). Based on this review, it is concluded that multicentric spread of JPA occurs more frequently than was previously recognized. In patients with subtotally resected JPA and several years of follow-up review via magnetic resonance imaging, the incidence of recurrence in a site different from the original was 12%. Patients with subtotally resected JPA in the hypothalamic region should be considered to be at high risk for developing multicentric spread. Chemotherapy appears useful in stabilizing multicentric disease. Earlier detection and intervention may result in longer disease-free survival in patients with multicentric spread of JPA.

Idiopathic hypertrophic cranial pachymeningitis. Report of three cases.

Hypertrophic cranial pachymeningitis is a rare, idiopathic form of granulomatous pachymeningitis. This report describes three cases of hypertrophic cranial pachymeningitis and discusses the clinical, radiographic, and pathological findings in these and other reported cases. These lesions typically cause progressive cranial nerve palsies, headaches, and cerebellar dysfunction. They occur in patients of all age groups; the peak incidence is in the sixth decade. Hypertrophic cranial pachymeningitis is best identified by magnetic resonance imaging. The diagnosis is established by excluding all other granulomatous and infectious diseases. A dural biopsy is essential to confirm the diagnosis. Hypertrophic cranial pachymeningitis is initially responsive to steroid therapy, but in most cases it recurs or progresses despite treatment. Surgical excision of granulomas is occasionally necessary to alleviate a mass effect. The long-term outcome remains uncertain for most patients, but progressive disease is usually fatal owing to cranial neuropathies.