Isolated focal dystonia phenotypes are associated with distinct patterns of altered microstructure.

Objective: Isolated adult-onset focal dystonia is considered a network disorder with disturbances to the motor basal ganglia and cerebellar circuits playing a pathophysiological role, but why specific body regions become affected remains unknown. We aimed to use diffusion tensor imaging to determine if the two most common phenotypes of focal dystonia are associated with distinguishing microstructural changes affecting the motor network. Methods: Fifteen blepharospasm patients, 20 cervical dystonia patients, and 30 age- and sex-matched healthy controls were recruited. Maps of fractional anisotropy and mean diffusivity were analyzed using a voxel-based approach and an automated region-of-interest technique to evaluate deep gray matter nuclei. Correlations between diffusion measures and dystonia severity were tested, and post hoc discriminant analyses were conducted. Results: Voxel-based analyses revealed significantly reduced fractional anisotropy in the right cerebellum and increased mean diffusivity in the left caudate of cervical dystonia patients compared to controls, as well as lower fractional anisotropy in the right cerebellum in cervical dystonia patients relative to blepharospasm patients. In addition to reduced fractional anisotropy in the bilateral caudate nucleus of cervical dystonia patients relative to controls and blepharospasm patients, region-of-interest analyses revealed significantly reduced fractional anisotropy in the right globus pallidus internus and left red nucleus of blepharospasm patients compared to both controls and cervical dystonia patients. Diffusivity measures in the red nucleus of blepharospasm patients correlated with disease severity. In a three-group discriminant analysis, participants were correctly classified with only modest reliability (67-75%), but in a two-group discriminant analysis, patients could be distinguished from each other with high reliability (83-100%). Conclusions: Different focal dystonia phenotypes are associated with distinct patterns of altered microstructure within constituent regions of basal ganglia and cerebellar circuits.

Curative and palliative MRI-guided laser ablation for drug-resistant epilepsy.

Epilepsy is a common neurological disorder occurring in 3% of the US adult population. It is characterised by seizures resulting from aberrant hypersynchronous neural activity. Approximately one-third of newly diagnosed epilepsy cases fail to become seizure-free in response to antiseizure drugs. Optimal seizure control, in cases of drug-resistant epilepsy, often requires neurosurgical intervention targeting seizure foci, such as the temporal lobe. Advances in minimally invasive ablative surgical approaches have led to the development of MRI-guided laser interstitial thermal therapy (LITT). For refractory epilepsy, this surgical intervention offers many advantages over traditional approaches, including real-time lesion monitoring, reduced morbidity, and in some reports increased preservation of cognitive and language processes. We review the use of LITT for epileptic indications in the context of its application as a curative (seizure freedom) or palliative (seizure reduction) measure for both lesional and non-lesional forms of epilepsy. Furthermore, we address the use of LITT for a variety of extratemporal lobe epilepsies. Finally, we describe clinical outcomes, limitations and future applications of LITT for epilepsy.

The Addition of Endovascular Intervention for Dural Venous Sinus Thrombosis: Single-Center Experience and Review of Literature.

BACKGROUND: Dural venous sinus thrombosis (DVST) is a cause of infarction and intracranial hemorrhage (ICH) that can lead to significant morbidity. Endovascular therapy has emerged as an adjunctive therapy in select cases but has been associated with increased hemorrhagic complications. We present our experience with a large single-center cohort of DVST cases treated with current-generation thrombectomy devices. MATERIALS AND METHODS: In this retrospective cohort study, a chart review was performed to compare presentations and outcomes of patients treated with anticoagulation alone with those treated with additional interventional therapy, using the modified Rankin Scale (mRS) score at discharge and at 90 days' follow-up. RESULTS: A total of 66 patients were included; 37 were treated with anticoagulation alone, and 29 underwent additional interventional therapy. Patients presenting with ICH or infarction had a significantly greater likelihood of disability at the time of discharge (odds ratio [OR] of 64.5 and 45.8, respectively; P < .0001) and at 90 days (OR of 28.4 and 22.8, respectively; P < .0001). Patients presenting with ICH or infarction were more likely to be selected for endovascular therapy (P < .05). Endovascular therapy was typically performed within 24 hours of admission; 9 patients (31%) had post-treatment hemorrhage, with 2 being (6.9%) symptomatic. There were fewer patients with slight disability (mRS score ≤1) in the endovascular group compared with the anticoagulation group at discharge (P = .05), but outcomes were not significantly different at 90 days (P = .19). CONCLUSIONS: Despite a higher rate of ICH or infarction at presentation in the endovascular group and an increased risk of postprocedural ICH, both treatment groups had similarly good functional outcomes at 90 days.

Imaging of Laser Therapy in Epilepsy.

BACKGROUND AND PURPOSE: MR-guided laser interstitial thermal therapy (MRgLITT) is an increasingly popular neuroablative method for the surgical treatment of epilepsy patients. This article intends to demonstrate the utility and pitfalls of imaging in the context of patient care with MRgLITT. MATERIAL AND METHODS: A retrospective review of the medical records and imaging database with six illustrative cases selected to demonstrate the use of imaging throughout patient management with MRgLITT in diverse clinical situations and pathologies. A review of the knowledge in the literature was applied to the relevant points discussed. RESULTS: Imaging findings were described in the setting of laser therapy in nonlesional epilepsy, mesial temporal sclerosis, dual pathology, periventricular nodular heterotopia, and schizencephaly. Discussion of imaging principles, potential pitfalls, as well as its use in the patient work-up and follow-up, is shown. CONCLUSIONS: MRgLITT is an alternative minimally invasive therapy for refractory epilepsy, which is becoming widely sought for. Imaging plays a crucial role prior to, during, and after the procedure.

Microstructural Changes within the Basal Ganglia Differ between Parkinson Disease Subtypes.

Diffusion tensor imaging (DTI) of the substantia nigra has shown promise in detecting and quantifying neurodegeneration in Parkinson disease (PD). It remains unknown, however, whether differences in microstructural changes within the basal ganglia underlie PD motor subtypes. We investigated microstructural changes within the basal ganglia of mild to moderately affected PD patients using DTI and sought to determine if microstructural changes differ between the tremor dominant (TD) and postural instability/gait difficulty (PIGD) subtypes. Fractional anisotropy, mean diffusivity, radial, and axial diffusivity were obtained from bilateral caudate, putamen, globus pallidus, and substantia nigra of 21 PD patients (12 TD and 9 PIGD) and 20 age-matched healthy controls. T-tests and ANOVA methods were used to compare PD patients, subtypes, and controls, and Spearman correlations tested for relationships between DTI and clinical measures. We found our cohort of PD patients had reduced fractional anisotropy within the substantia nigra and increased mean and radial diffusivity within the substantia nigra and globus pallidus compared to controls, and that changes within those structures were largely driven by the PIGD subtype. Across all PD patients fractional anisotropy within the substantia nigra correlated with disease stage, while in PIGD patients increased diffusivity within the globus pallidus correlated with disease stage and motor severity. We conclude that PIGD patients have more severely affected microstructural changes within the substantia nigra compared to TD, and that microstructural changes within the globus pallidus may be particularly relevant for the manifestation of the PIGD subtype.

Sensory and motor deficits in children with cerebral palsy born preterm correlate with diffusion tensor imaging abnormalities in thalamocortical pathways.

AIM: Cerebral palsy (CP) is frequently linked to white matter injury in children born preterm. Diffusion tensor imaging (DTI) is a powerful technique providing precise identification of white matter microstructure. We investigated the relationship between DTI-observed thalamocortical (posterior thalamic radiation) injury, motor (corticospinal tract) injury, and sensorimotor function. METHOD: Twenty-eight children born preterm (16 males, 12 females; mean age 5y 10mo, SD 2y 6mo, range 16mo-13y; mean gestational age at birth 28wks, SD 2.7wks, range 23-34wks) were included in this case-control study. Twenty-one children had spastic diplegia, four had spastic quadriplegia, two had hemiplegia, and one had ataxic/hypotonic CP; 15 of the participants walked independently. Normative comparison data were obtained from 35 healthy age-matched children born at term (19 males, 16 females; mean age 5y 9mo, SD 4y 4mo, range 15mo-15y). Two-dimensional DTI color maps were created to evaluate 26 central white matter tracts, which were graded by a neuroradiologist masked to clinical status. Quantitative measures of touch, proprioception, strength (dynamometer), and spasticity (modified Ashworth scale) were obtained from a subset of participants. RESULTS: All 28 participants with CP had periventricular white-matter injury on magnetic resonance imaging. Using DTI color maps, there was more severe injury in the posterior thalamic radiation pathways than in the descending corticospinal tracts. Posterior thalamic radiation injury correlated with reduced contralateral touch threshold, proprioception, and motor severity, whereas corticospinal tract injury did not correlate with motor or sensory outcome measures. INTERPRETATION: These findings extend previous research demonstrating that CP in preterm children reflects disruption of thalamocortical connections as well as descending corticospinal pathways.

Brain metabolism in Rett syndrome: age, clinical, and genotype correlations.

OBJECTIVE: Brain metabolism, as studied by magnetic resonance spectroscopy (MRS), has been previously shown to be abnormal in Rett syndrome (RTT). This study reports the relation of MRS findings to age, disease severity, and genotype. METHODS: Forty RTT girls (1-14 years old) and 12 age-matched control subjects were examined. Single-voxel proton MRS of left frontal white matter was performed. RESULTS: NAA/Cr ratios decreased and myoinositol/Cr ratios increased with age in RTT patients (both p < 0.03), whereas these ratios were stable in control. The mean glutamate and glutamine/Cr ratio was 36% greater in RTT patients than in control (p = 0.043). The mean NAA/Cr ratio was 12.6% lower in RTT patients with seizures compared with those without seizures (p = 0.017). NAA/Cr ratios decreased with increasing clinical severity score (p = 0.031). Compared with patients with T158X, R255X, and R294X mutations, and C-terminal deletions, patients with the R168X mutation tended to have the greatest severity score (0.01 < or = p < or = 0.11) and the lowest NAA/Cr ratio (0.029 < or = p < 0.14). INTERPRETATION: Decreasing NAA/Cr and increasing myoinositol/Cr with age are suggestive of progressive axonal damage and astrocytosis in RTT, respectively, whereas increased glutamate and glutamine/Cr ratio may be secondary to increasing glutamate/glutamine cycling at the synaptic level. The relations between NAA/Cr, presence or absence of seizures, and disease severity suggest that MRS provides a noninvasive measure of cerebral involvement in RTT.

Diffusion tensor imaging in children and adolescents: reproducibility, hemispheric, and age-related differences.

UNLABELLED: We evaluated intra-rater, inter-rater, and between-scan reproducibility, hemispheric differences, and the effect of age on apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in healthy children (age range 5.5-19.1 years) examined with a clinical diffusion tensor imaging (DTI) protocol at 1.5 T, using a region of interest (ROI) methodology. Measures of reliability and precision were assessed in six ROIs using two different ROI shapes (polygonal and ellipsoidal). RESULTS: Highly reproducible values of ADC and FA were obtained with the polygonal method on intra-rater (coefficients of variation