Milos Kerkovsky

Cross-sectional transverse area and hyperintensities on magnetic resonance imaging in relation to the clinical picture in cervical spondylotic myelopathy.

Study Design. Prospective observational cohort study. Objective. To ascertain the threshold of critical spondylotic cervical cord compression and its relation to MRI-increased signal intensities. Summary of Background Data. The critical degree of spinal cord compression required to induce significant clinical signs remains unknown. Methods. The study group consisted of 243 patients (mean age, 53.9 ± 9.8 years), with spondylotic cervical spine compression. The transverse cross-sectional area of the spinal cord at the level of maximum compression was measured, while MRI hyperintensities were recorded and related to clinical status and quantified by modified JOA score (mJOA). Results. A statistically significant difference in mJOA was shown between patients with a spinal cord sectional area of under 50 mm2 and a group of patients with a spinal cord sectional area of over 60 mm2. This difference was highly significant (P = 0.001) in a subgroup with MRI hyperintensities (187 patients, P = 0.001), whereas within the group of patients without hyperintensities this difference was not observed (P = 0.63). Conclusion. The critical degree of spinal cord compression needed to induce clinically significant signs was found between 50 and 60 mm2 of cross-sectional transverse area at the level of maximal compression in association with MRI hyperintensities.

Cortico-cerebellar functional connectivity and sequencing of movements in schizophrenia.

BackgroundAbnormal execution of several movements in a sequence is a frequent finding in schizophrenia. Successful performance of such motor acts requires correct integration of cortico-subcortical processes, particularly those related to cerebellar functions. Abnormal connectivity between cortical and cerebellar regions with resulting cognitive dysmetria has been proposed as the core dysfunction behind many signs and symptoms of schizophrenia. The aim of the present study was to assess if these proposed abnormalities in connectivity are a unifying feature of schizophrenia, or, rather, reflect a specific symptom domain of a heterogeneous disease. We predicted that abnormal functional connectivity between the motor cortex and cerebellum would be linked with abnormal performance of movement sequencing.MethodsWe examined 24 schizophrenia patients (SCH) and 24 age-, sex-, and handedness-matched healthy controls (HC) using fMRI during a modified finger-tapping task. The ability to perform movement sequencing was tested using the Neurological Evaluation Scale (NES). The subjects were categorized into two groups, with (SQ+) and without (SQ-) movement sequencing abnormalities, according to the NES-SQ score. The effects of diagnosis and movement sequencing abnormalities on the functional connectivity parameters between the motor cortex and cerebellum (MC-CRBL) and the supplementary motor cortex and cerebellum (SMA-CRBL) activated during the motor task were analyzed.ResultsWe found no effect of diagnosis on the functional connectivity measures. There was, however, a significant effect on the SQ group: SQ + patients showed a lower level of MC-CRBL connectivity than SQ- patients and healthy controls. Moreover, the level of MC-CRBL and SMA-CRBL negatively correlated with the magnitude of NES-SQ abnormalities, but with no other NES domain.ConclusionsAbnormal cortico-cerebellar functional connectivity during the execution of a motor task is linked with movement sequencing abnormalities in schizophrenia, but not with the diagnosis of schizophrenia per se. It seems that specific patterns of inter-regional connectivity are linked with corresponding signs and symptoms of clinically heterogeneous conditions such as schizophrenia.

Abnormalities in Myelination of the Superior Cerebellar Peduncle in Patients with Schizophrenia and Deficits in Movement Sequencing

Deficits in the execution of a sequence of movements are common in schizophrenia. Previous studies reported reduced functional activity in the motor cortex and cerebellum in schizophrenic patients with deficits in movement sequencing. The corticospinal tract (CST) and superior cerebellar peduncle (SCP) are fiber tracts that are involved in movement sequencing. However, the integrity of these tracts has not been evaluated in schizophrenic patients with respect to the performance of movement sequencing yet. Diffusion tensor magnetic resonance images (DT-MRI) were acquired from 24 patients with schizophrenia and 23 matched control subjects. Tractography was applied to reconstruct the CST and SCP and DT-MRI-specific parameters such as fractional anisotropy (FA) and radial diffusivity (RD) were reported. The patient group was further subdivided based on the score of sequencing of complex motor acts subscale of the Neurological Evaluation Scale into those with deficits in sequencing motor acts, the SQabn group (n = 7), and those with normal performance, the SQnorm group (n = 17). Schizophrenia patients of the SQnorm subgroup had significantly reduced FA and increased RD values in the right CST in comparison to the control group; the SQabn subgroup did not differ from the controls. However, the SQabn subgroup showed impaired integrity of the left SCP, whereas the SQnorm subgroup did not. Abnormalities in the right CST in the SQnorm and in the left SCP in SQabn groups suggest that the patients with SQabn represent subgroups with distinct deficits. Moreover, these results demonstrate the involvement of the SCP in the pathogenesis of movement sequencing in schizophrenia.

Towards a predictive model for post-stroke delirium

Primary objective: To assess predisposing and precipitating risk factors and create a predictive model for post-stroke delirium. Research design: A prospective observational study in a cohort of consecutive patients with ischemic stroke or intracerebral haematoma admitted within 24 hours of stroke onset. Methods: Patients were assessed daily for delirium during the first week by means of DSM-IV criteria and risk factors were recorded. Results: One hundred patients completed a 7-day evaluation (47 women and 53 men, median age 77 years). An episode of delirium was detected in 43 patients (43%). Using multivariate logistic regression, a predictive statistical model was developed that utilized independent risk factors: age (OR = 1.08; 95% CI = 1.02–1.15); intracerebral haemorrhage (OR = 6.11; 95% CI = 1.62–22.98), lesion volume > 40 ccm (OR = 3.99; 95% CI = 1.29–12.39) and either elevated gamma-glytamyl transferase (OR = 4.88; 95% CI = 1.45–16.35) and elevated serum bilirubin (OR = 3.70; 95% CI = 1.32–10.38) or maximum sequential organ failure assessment score >2 (OR = 3.33; 95% CI = 1.06–10.45) with acceptable sensitivity and specificity (69.0% and 80.7%). In ischemic strokes, total anterior circulation infarctions were more frequently associated with delirium (73.3% developed delirium) compared with the remainder of the groups combined (p = 0.004; OR = 6.66; 95% CI = 1.85–24.01). Conclusion: Higher age, metabolic disturbances, intracerebral haemorrhage and larger ischemic hemispheric strokes increase the risk of post-stroke delirium.

Prevalence and Imaging Characteristics of Nonmyelopathic and Myelopathic Spondylotic Cervical Cord Compression.

Study Design. Cross-sectional population-based observational study. Objective. To estimate the prevalence of nonmyelopathic spondylotic cervical cord compression (NMSCCC) and cervical spondylotic myelopathy (CSM) in a population older than 40 years and to evaluate the magnetic resonance imaging (MRI) characteristics of these conditions. Summary of Background Data. The prevalence of neither NMSCCC nor CSM is known and there exists no commonly accepted quantitative MRI definition of cervical cord compression. Methods. A group of 183 randomly recruited volunteers, 93 women, median age 66 years, range 40–80 years, underwent MRI examination of the cervical spine and spinal cord on a 1.5 T device using conventional sequences from disc levels C2/C3 to C6/C7. The imaging criterion for cervical cord compression was defined as a change in spinal cord contour at the level of an intervertebral disc on axial or sagittal MRI scan. Results. MRI signs of cervical cord compression were found in 108 individuals (59.0%; 95% CI: 51.5%–66.2%); their numbers increased with age from 31.6% in the fifth decade to 66.8% in the eighth. Clinical signs of symptomatic CSM were found in two cases (1.1%), and 75 cases (41.0%) were without compression. An anteroposterior cervical canal diameter at the level of intervertebral disc (CDdisc) of less than 9.9 mm was associated with the highest probability of NMSCCC—odds ratio (OR) = 32.5, followed by a compression ratio of ⩽0.5: OR = 11.1. Conclusion. The prevalence of NMSCCC in a population older than 40 years is higher than previously reported and increases with age. CDdisc and compression ratio had the highest capacity to discriminate between subjects with and without asymptomatic compression, and their cut-off values could be used to objectify criteria for cervical cord compression. Level of Evidence: 2

Neuronal substrate and effective connectivity of abnormal movement sequencing in schizophrenia

Movement sequencing difficulties are part of the neurological soft signs (NSS), they have high clinical value because they are not always present in schizophrenia. We investigated the neuronal correlates of movement sequencing in 24 healthy controls and 24 schizophrenia patients, with (SZP SQ+) or without (SZP SQ-) sequencing difficulties. We characterized simultaneous and lagged functional connectivity between brain regions involved in movement sequencing using psychophysiological interaction (PPI) and the Granger causality modeling (GCM), respectively. Left premotor cortex (PMC) and superior parietal lobule (SPL) were specifically activated during sequential movements in all participants. Right PMC and precuneus, ipsilateral to the hand executing the task, activated during sequential movements only in healthy controls and SZP SQ-. SZP SQ+ showed hyperactivation in contralateral PMC, as compared to the other groups. PPI analysis revealed a deficit in inhibitory connections within this fronto-parietal network in SZP SQ+ during sequential task. GCM showed a significant lagged effective connectivity from right PMC to left SPL during task and rest periods in all groups and from right PMC to right precuneus in SZP SQ+ group only. Both SZP groups had a significant lagged connectivity from right to left PMC, during sequential task. Our results indicate that aberrant fronto-parietal network connectivity with cortical inhibition deficit and abnormal reliance on previous network activity are related to movement sequencing in SZP. The overactivation of motor cortex seems to be a good compensating strategy, the hyperactivation of parietal cortex is linked to motor deficit symptoms.

Predictors of symptomatic myelopathy in degenerative cervical spinal cord compression

To update a previously established list of predictors for neurological cervical cord dysfunction in nonmyelopathic degenerative cervical cord compression (NMDCCC).