Neurology June 2009 Volume 72 Issue 24

Background: Methamphetamine use is a common problem among women of childbearing age, leading to an increasing number of children with prenatal methamphetamine exposure. Whether microstructural brain changes associated with prenatal methamphetamine exposure can be detected with diffusion tensor imaging (DTI) is unknown.Method: Twelve-direction DTI was performed in 29 methamphetamine-exposed and 37 unexposed children ages 3-4 years on a 3-T MRI scanner. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were determined in the corpus callosum (genu and splenium) and bilaterally in the frontal and parietal white matter (WM), basal ganglia (caudate, putamen, globus pallidus), and thalamus.Results: Children with prenatal methamphetamine exposure had lower ADC in the frontal (right: -2.1%, p = 0.04; left: -2.0%, p = 0.09) and parietal WM (right: -3.9%, p = 0.002; left: -3.3%, p = 0.02) compared to unexposed children. The methamphetamine-exposed children also showed a trend for higher FA in the left frontal WM (+4.9%, p = 0.06) compared to the unexposed children.Conclusion: Since less myelination and higher dendritic or spine density have been reported in animals exposed to methamphetamine, lower diffusion in our children may reflect more compact axons or greater dendritic or spine density associated with prenatal methamphetamine exposure. These findings suggest alterations in white matter maturation in these children exposed to methamphetamine in utero.(C)2009AAN Enterprises, Inc.

Background: Hirayama disease (brachial monomelic amyotrophy) is a unilateral or grossly asymmetric bilateral disease. Bilaterally symmetric involvement has never been described.Methods: Based on cardinal clinical and MRI criteria, a total of 106 patients with Hirayama disease from two tertiary care hospitals of North India seen between 1992 and 2008 formed the basis of this study. All those found to have bilaterally symmetric involvement on clinical and electrophysiologic basis were evaluated for clinical, electrophysiologic, and MRI correlates other than those required for the diagnosis.Results: Eleven patients, who constituted around 10% of all the patients with Hirayama disease, were found to have bilaterally symmetric involvement. Nine of them had a history of unilateral onset. The important characteristics of this type of presentation included severe weakness and wasting in C7, C8, and T1 myotomes that frequently spilled over to C6 segment, predominant autonomic dysfunction in distal upper extremities in the form of cold paresis, cold skin, excessive sweating, and hair loss over the dorsum of the hands, and a very prominent bilateral minipolymyoclonus. MRI during complete flexion of neck showed severe flattening of lower cervical spinal cord against C5-C6 vertebral bodies and development of a crescent-shaped enhancing epidural space extending from C4 to T2 spine.Conclusion: Bilaterally symmetric Hirayama disease is a severe form of a classic disease which remains undiagnosed due to a common notion that it is a unilateral or grossly asymmetric disease. This description calls for review of the term "brachial monomelic amyotrophy" described to denote this disease.(C)2009AAN Enterprises, Inc.

Objective: To determine whether changes in D2 receptor availability are present in carriers of genetic mutations for primary dystonia.Methods: Manifesting and nonmanifesting carriers of the DYT1 and DYT6 dystonia mutations were scanned with [11C] raclopride (RAC) and PET. Measures of D2 receptor availability in the caudate nucleus and putamen were determined using an automated region-of-interest approach. Values from mutation carriers and healthy controls were compared using analysis of variance to assess the effects of genotype and phenotype. Additionally, voxel-based whole brain searches were conducted to detect group differences in extrastriatal regions.Results: Significant reductions in caudate and putamen D2 receptor availability were evident in both groups of mutation carriers relative to healthy controls (p < 0.001). The changes were greater in DYT6 relative to DYT1 carriers (-38.0 +/- 3.0% vs -15.0 +/- 3.0%, p < 0.001). By contrast, there was no significant difference between manifesting and nonmanifesting carriers of either genotype. Voxel-based analysis confirmed these findings and additionally revealed reduced RAC binding in the ventrolateral thalamus of both groups of mutation carriers. As in the striatum, the thalamic binding reductions were more pronounced in DYT6 carriers and were not influenced by the presence of clinical manifestations.Conclusions: Reduced D2 receptor availability in carriers of dystonia genes is compatible with dysfunction or loss of D2-bearing neurons, increased synaptic dopamine levels, or both. These changes, which may be present to different degrees in the DYT1 and DYT6 genotypes, are likely to represent susceptibility factors for the development of clinical manifestations in mutation carriers.(C)2009AAN Enterprises, Inc.

Background: Migraine is associated with increased risk of cardiovascular disease, but the mechanisms are unclear.Objective: To investigate the activity of endothelial and vascular smooth muscle cells (VSMCs) in patients with migraine.Methods: Case-control study of 12 patients with migraine without aura and 12 matched healthy control subjects. Endothelial and VSMC components of vascular reactivity were explored by plethysmography measurement of forearm blood flow (FBF) during infusions of vasoactive agents into the brachial artery. Forearm production of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) was also quantified.Results: In patients with migraine, the vasodilating effect of acetylcholine (ACh), an endothelium-dependent vasodilator, was markedly reduced (p < 0.001 by analysis of variance). In response to the highest dose of ACh, FBF rose to 8.6 +/- 2.2 in patients with migraine and to 22.7 +/- 3.0 mL x dL-1 x min-1 in controls (p = 0.001). The dose-response curve to nitroprusside, a vasodilator directly acting on VSMCs, was depressed in patients with migraine (p < 0.001 by analysis of variance). The maximal response of FBF to nitroprusside was 12.1 +/- 2.0 in patients with migraine and 24.1 +/- 1.8 mL x dl-1 x min-1 in controls (p < 0.001). During ACh infusion, NO release from the endothelium was similar in patients and controls. In contrast, there was a marked release of cGMP from VSMCs in controls, but not in patients with migraine (-1.9 +/- 2.2 in patients with migraine and -19.1 +/- 5.4 nmol x dL-1 x min-1 in controls; p = 0.03).Conclusions: Patients with migraine are characterized by a distinct vascular smooth muscle cell dysfunction, revealed by impaired cyclic guanosine monophosphate and hemodynamic response to nitric oxide.(C)2009AAN Enterprises, Inc.

Objective: To investigate clinical and economic consequences following generic substitution of one vs multiple generics of topiramate (Topamax; Ortho-McNeil Neurologics, Titusville, NJ).Methods: Medical and pharmacy claims data of Regie de l'Assurance-Maladie du Quebec from January 2006 to October 2007 were used. Patients with epilepsy treated with topiramate were selected. An open-cohort design was used to classify the observation period into periods of brand, single-generic, and multiple-generic use. One-year generic-switch and switchback-to-brand rates were estimated using Kaplan-Meier methodology. Medical resource utilization and costs were compared among the three periods using multivariate regression analysis.Results: In total, 948 patients were observed during 1,105 person-years of brand use, 233 person-years of single-generic use, and 92 person-years of multiple-generic use. A total of 23% of generic users received at least two different generic versions. Compared to brand use, multiple-generic use was associated with higher utilization of other prescription drugs (incidence rate ratio [IRR] = 1.27, 95% confidence interval [CI] = 1.24-1.31), higher hospitalization rates (0.48 vs 0.83 visit/person-year, IRR = 1.65, 95% CI = 1.28-2.13), and longer hospital stays (2.6 vs 3.9 days/person-year, IRR = 1.43, 95% CI = 1.27-1.60), but the effect was less pronounced in single-generic use (hospitalization: IRR = 1.08, 95% CI = 0.88-1.34, length of stay: IRR = 1.12, 95% CI = 1.03-1.23). The risk of head injury or fracture was nearly three times higher (hazard ratio = 2.84, 95% CI = 1.24-6.48) following a generic-to-generic switch compared to brand use. The total annualized health care cost per patient was higher in the multiple-generic than brand periods by C$1,716 (cost ratio = 1.21, p = 0.0420).Conclusion: Multiple-generic substitution of topiramate was significantly associated with negative outcomes, such as hospitalizations and injuries, and increased health care costs.(C)2009AAN Enterprises, Inc.