Daniel Horinek

Spatial navigation impairment is proportional to right hippocampal volume

Cognitive deficits in older adults attributable to Alzheimers disease (AD) pathology are featured early on by hippocampal impairment. Among these individuals, deterioration in spatial navigation, manifested by poor hippocampus-dependent allocentric navigation, may occur well before the clinical onset of dementia. Our aim was to determine whether allocentric spatial navigation impairment would be proportional to right hippocampal volume loss irrespective of general brain atrophy. We also contrasted the respective spatial navigation scores of the real-space human Morris water maze with its corresponding 2D computer version. We included 42 cognitively impaired patients with either amnestic mild cognitive impairment (n = 23) or mild and moderate AD (n = 19), and 14 cognitively intact older controls. All participants underwent 1.5T MRI brain scanning with subsequent automatic measurement of the total brain and hippocampal (right and left) volumes. Allocentric spatial navigation was tested in the real-space version of the human Morris water maze and in its corresponding computer version. Participants used two navigational cues to locate an invisible goal independent of the start position. We found that smaller right hippocampal volume was associated with poorer navigation performance in both the real-space (β = −0.62, P < 0.001) and virtual (β = −0.43, P = 0.026) versions, controlling for demographic variables, total brain and left hippocampal volumes. In subsequent analyses, the results were significant in cognitively impaired (P ≤ 0.05) but not in cognitively healthy (P > 0.59) subjects. The respective real-space and virtual scores strongly correlated with each other. Our findings indicate that the right hippocampus plays a critical role in allocentric navigation, particularly when cognitive impairment is present.

Long-term Outcomes After Nonlesional Extratemporal Lobe Epilepsy Surgery

IMPORTANCE A focal lesion detected by use of magnetic resonance imaging (MRI) is a favorable prognostic finding for epilepsy surgery. Patients with normal MRI findings and extratemporal lobe epilepsy have less favorable outcomes. Most studies investigating the outcomes of patients with normal MRI findings who underwent (nonlesional) extratemporal epilepsy surgery are confined to a highly select group of patients with limited follow-up. OBJECTIVE To evaluate noninvasive diagnostic test results and their association with excellent surgical outcomes (defined using Engel classes I-IIA of surgical outcomes) in a group of patients with medically resistant nonlesional extratemporal epilepsy. DESIGN A retrospective study. SETTING Mayo Clinic, Rochester, Minnesota. PARTICIPANTS From 1997 through 2002, we identified 85 patients with medically resistant extratemporal lobe epilepsy who had normal MRI findings. Based on a standardized presurgical evaluation and review at a multidisciplinary epilepsy surgery conference, some of these patients were selected for intracranial electroencephalographic (EEG) monitoring and epilepsy surgery. EXPOSURE Nonlesional extratemporal lobe epilepsy surgery. MAIN OUTCOMES AND MEASURES The results of noninvasive diagnostic tests and the clinical variables potentially associated with excellent surgical outcome were examined in patients with a minimum follow-up of 1 year (mean follow-up, 9 years). RESULTS Based on the noninvasive diagnostic test results, a clear hypothesis for seizure origin was possible for 47 of the 85 patients (55%), and 31 of these 47 patients (66%) proceeded to intracranial EEG monitoring. For 24 of these 31 patients undergoing long-term intracranial EEG (77%), a seizure focus was identified and surgically resected. Of these 24 patients, 9 (38%) had an excellent outcome after resective epilepsy surgery. All patients with an excellent surgical outcome had at least 10 years of follow-up. Univariate analysis showed that localized interictal epileptiform discharges on scalp EEGs were associated with an excellent surgical outcome. CONCLUSIONS AND RELEVANCE Scalp EEG was the most useful test for identifying patients with normal MRI findings and extratemporal lobe epilepsy who were likely to have excellent outcomes after epilepsy surgery. Extending outcome analysis beyond the resective surgery group to the entire group of patients who were evaluated further highlights the challenge that these patients pose. Although 9 of 24 patients undergoing resective surgery (38%) had excellent outcomes, only 9 of 31 patients undergoing intracranial EEG (29%) and only 9 of 85 patient with nonlesional extratemporal lobe epilepsy (11%) had long-term excellent outcomes.

Volumetry of the human amygdala — An anatomical study

A striking feature of the studies that have addressed the measurement of the amygdala is the wide range of volumes encountered, with reports of volumes ranging from 1 to almost 4 cm(3). Another striking feature is the number of discrepancies in the landmarks adopted for manual tracing in magnetic resonance imaging (MRI). The goal of our study was to assess the anatomical volume of the amygdala on the basis of its cytoarchitecture while comparing the differences in age and sex. This study was performed on 21 normal male brains (mean age of 56.8 years) and 9 normal female brains (mean age of 61.2 years). The volume of the amygdala was measured by planimetry of Nissl-stained serial sections using ImageJ software. To address the complexity of the amygdala, we elected to use two types of amygdalar measurement that differ mainly in the definition of anterior pole boundaries. The average size of the classic amygdala was 1.24 cm(3) (S.D.=0.14), while the average size of the amygdala with wider borders was 1.63 cm(3) (S.D.=0.2). No interhemispheric or intersexual differences were observed for either type of amygdalar measurement. Neither sex revealed any statistically important relationship between volume of the amygdala and age. Our study was concerned exclusively with the anatomical volume of the amygdala rather than the MRI volume. Nevertheless, our results may have important implications for MRI studies because as of yet there is no gold standard for manual volumetry of the amygdala.

Amygdalar volume and psychiatric symptoms in Alzheimer's disease: an MRI analysis

Objectives –  We measured the volumes of the amygdala to test the hypothesis that the reduction of amygdalar volume may be associated with psychiatric symptoms in Alzheimers disease.

Statistical SPECT processing in MRI-negative epilepsy surgery

Objective: To evaluate the benefit of statistical SPECT processing over traditional subtraction methods, we compared ictal–interictal SPECT analyzed by statistical parametric mapping (SPM) (ISAS), statistical ictal SPECT coregistered to MRI (STATISCOM), and subtraction ictal–interictal SPECT coregistered with MRI (SISCOM) in patients with MRI-negative focal temporal lobe epilepsy (nTLE) and extratemporal lobe epilepsy (nETLE). Methods: We retrospectively identified 49 consecutive cases of drug-resistant focal epilepsy that had a negative preoperative MRI and underwent interictal and ictal SPECT prior to resective epilepsy surgery. Interictal and ictal SPECT scans were analyzed using SISCOM, ISAS, and STATISCOM to create hyperperfusion and hypoperfusion maps for each patient. Reviewers blinded to clinical data and the SPECT analysis method marked the site of probable seizure origin and indicated their confidence in the localization. Results: In nTLE and nETLE, the hyperperfusions detected by STATISCOM (71% nTLE, 57% nETLE) and ISAS (67% nTLE, 53% nETLE) were more often colocalized with surgery resection site compared to SISCOM (38% nTLE, 36% nETLE). In nTLE, localization of the hyperperfusion to the region of surgery was associated with an excellent outcome for STATISCOM (p = 0.005) and ISAS (p = 0.027), but not in SISCOM (p = 0.071). This association was not present in nETLE for any method. Conclusion: In an unselected group of patients with normal MRI and focal epilepsy, SPM-based methods of SPECT processing showed better localization of SPECT hyperperfusion to surgical resection site and higher interobserver agreement compared to SISCOM. These results show the benefit of statistical SPECT processing methods and further highlight the challenge of nETLE.

Neurosonological Examination: A Non-Invasive Approach for the Detection of Cerebrovascular Impairment in AD

There has been a growing interest in vascular impairment associated with Alzheimer’s disease (AD). This interest was stimulated by the findings of higher incidence of vascular risk factors in AD. Signs of vascular impairment were investigated notably in the field of imaging methods. Our aim was to explore ultrasonographic studies of extra- and intracranial vessels in patients with AD and mild cognitive impairment (MCI) and define implications for diagnosis, treatment, and prevention of the disease. The most frequently studied parameters with extracranial ultrasound are intima-media thickness in common carotid artery, carotid atherosclerosis, and total cerebral blood flow. The transcranial ultrasound concentrates mostly on flow velocities, pulsatility indices, cerebrovascular reserve capacity, and cerebral microembolization. Studies suggest that there is morphological and functional impairment of cerebral circulation in AD compared to healthy subjects. Ultrasound as a non-invasive method could be potentially useful in identifying individuals in a higher risk of progression of cognitive decline.

Segmentation of Vertebral Bodies in MR Images

Segmentation of vertebral bodies is useful for diagnosis of certain spine pathologies, such as scoliosis, spondylolisthesis and vertebral fractures. In this paper, we present a fast and semi-automatic approach for spine segmentation in routine clinical MR images. Segmenting a single vertebra is based on multiple-feature boundary classification and mesh inflation, and starts with a simple point-in-vertebra initialization. The inflation retains a star-shape geometry to prevent selfintersections and uses a constrained subdivision hierarchy to control smoothness. Analyzing the shape of the first vertebra, the main spine direction is deduced and the locations of neighboring vertebral bodies are estimated for further segmentation. The method was tested on 11 routine lumbar datasets with 92 reference vertebrae resulting in a detection rate of 93%. The average Dice Similarity Coefficient (DSC) against manual reference segmentations was 78%, which is on par with state of the art. The main advantages of our method are high speed and a low amount of user interaction.

Bobble-head doll syndrome: therapeutic outcome and long-term follow-up in four children

Bobble-head doll syndrome (BHDS) is a complex syndrome with the dominant symptom of repetitive anteroposterior head movement. Only 57 patients are quoted in the literature. The etiology of this syndrome remains unknown and no standard treatment has yet been established. We hereby report four cases treated at our department. All the patients presented a psychomotor retardation due to an obstructive hydrocephalus. All the patients were treated using neuroendoscopic techniques: two with ventriculocystostomy, and two with ventriculocystocisternostomy. Cyst decompression was achieved in all four cases and clinical recovery was evident in three of the four patients observed. After surgery, BHDS persisted longer the more the subsequent treatment was delayed. In this article, we provide a concise overview of the theories of pathogenesis, presentation, and management of this syndrome. Based on our own experience, we state that the method of choice should be the neuroendoscopy and this must be performed promptly after diagnosis is made.

Evaluation of white matter alterations in Alzheimer's disease and normal pressure hydrocephalus as measured by diffusion weighted MRI

IN ALZHEIMER’S DISEASE AND NORMAL PRESSURE HYDROCEPHALUS AS MEASURED BY DIFFUSION WEIGHTED MRI Daniel Horinek, Irena Buksakowska, Nikoletta Szab o, Eszter T oth, Vlastimil Sulc, Luka s Martinkovi c, Ji r ı Vr ana, Martin Vyhnalek, Franti sek Charv at, Miloslav Ro cek, L aszl o V ecsei, Jakub Hort, Tam as Kinsces, Charles Universit, 1st Medical Faculty, and University Central Military Hospital, Prague, Czech Republic; Charles University in Prague and University Hospital Motol, Prague, Czech Republic; Albert Szent-Gy€orgyi Clinical Center, University of Szeged, Szeged, Hungary; International Research Center, St. Anne’s University Hospital, Brno, Czech Republic; Charles University, 2nd Medical Faculty and University Hospital Motol,, Czech Republic; 6 University Central Military Hospital, Prague, Czech Republic; 7 Department of Neurology, Motol University Hospital, Prague, Czech Republic; International Research Center, Brno, Czech Republic.

Radiographic changes after anterior cervical discectomy and their clinical impact.

Dear EditorWewouldliketopresentourexperiencewithanteriorcervicaldiscectomywithoutfusion(ACD).Thistechniquewasusedinthe department of the senior author during the years 1991–1999. A total number of 145 patients were operated on.Despite many studies concerning ACD, we felt that a reallylong term follow-up is lacking. This retrospective study eval-uates clinical and radiological results, with the longest pub-lished follow-up of 12.8 years. Our aim was to determineradiological biomarkers of poor outcome.Materials and methodsOnly patients with complete documentation who enabledus to contact them were eligible for enrollment, whichended up at 51 patients in the cohort. Four patientsunderwent three-level surgery, 27 two-level, and 20 one-level surgery. The number of surgeries in each level was2 at level C3/4, 13 at level C4/5, 42 at level C5/6, 28 atlevel C6/7, and 2 surgeries at level C7/Th1.AP lateral and dynamic X-ray was performed. The sagittalalignment of the cervical spine was measured using Cobb’sangle method between the inferior margin of C2 and theinferior margin of C7. The sagittal alignment was also evalu-ated at the level of surgery by measuring the angle betweenlines drawn at the superior margin of the superior and theinferior margin of the inferior vertebral body. Bone fusion atthe level of the surgery was studied in lateral and dynamicprojections using the criteria of Lee at al [4]. Odom’scriteriawere used for clinical evaluation [7].ResultsFour patients showed kyphosis of the cervical spine(7.84 %). Lordosis or straight axis was present in 47patients (92.16 %). Kyphosis in the level of surgery,which was considered as radiological failure, was pres-ent in 19 cases (37.25 %). 41 patients had definitefusion, and 5 patients had probable fusion; 3 patientshad possible pseudoarthrosis (5.88 %), and 2 had defi-nite pseudoarthrosis (3.92 %). Clinical examination di-vided the group (according to Odom’s criteria) intoclinical success with excellent (39.22 %), good(27.45 %), or fair (19.61 %) results and into failurewith poor results (7 patients, 13.72 %). Within thecohort we did not find any patient who required imme-diate reoperation.There was no correlation between the number of operatedsegments and poor clinical outcome.Radiographic and clinical correlationsThe cervical spine kyphosis was considered as unnaturalalignment and, therefore, should be associated with pooroutcome. However, no patient from the poor outcome grouppresented C2-7 kyphosis. Local kyphosis at the level of sur-gery, which was present in 5 out of 7 patients in the poor