Tuberous sclerosis complex: A tale of two genes Comments Off
SOX1 autoantibodies: Tumor markers in LEMS patients? Comments Off
Overlapping neurologic and cognitive phenotypes in patients with TSC1 or TSC2 mutations Comments Off
Objective: The purpose of this study was to systematically analyze the associations between different TSC1 and TSC2 mutations and the neurologic and cognitive phenotype in patients with tuberous sclerosis complex (TSC).
Methods: Mutation analysis was performed in 58 patients with TSC. Epilepsy variables, including EEG, were classified. A cognition index was determined based on a comprehensive neuropsychological assessment. On three-dimensional fluid-attenuated inversion recovery MR images, an automated tuber segmentation program detected and calculated the number of tubers and the proportion of total brain volume occupied by tubers (tuber/brain proportion [TBP]).
Results: As a group, patients with a TSC2 mutation had earlier age at seizure onset, lower cognition index, more tubers, and a greater TBP than those with a TSC1 mutation, but the ranges overlapped considerably. Familial cases were older at seizure onset and had a higher cognition index than nonfamilial cases. Patients with a mutation deleting or directly inactivating the tuberin GTPase activating protein (GAP) domain had more tubers and a greater TBP than those with an intact GAP domain. Patients with a truncating TSC1 or TSC2 mutation differed from those with nontruncating mutations in seizure types only.
Conclusions: Although patients with a TSC1 mutation are more likely to have a less severe neurologic and cognitive phenotype than those with a TSC2 mutation, the considerable overlap between both aspects of the phenotype implies that prediction of the neurologic and cognitive phenotypes in individuals with tuberous sclerosis complex should not be based on their particular TSC1 or TSC2 mutation.
Cognitive impairment in tuberous sclerosis complex is a multifactorial condition Comments Off
Objective: In patients with tuberous sclerosis complex (TSC), associations between tuber number, infantile spasms, and cognitive impairment have been proposed. We hypothesized that the tuber/brain proportion (TBP), the proportion of the total brain volume occupied by tubers, would be a better determinant of seizures and cognitive function than the number of tubers. We investigated tuber load, seizures, and cognitive function and their relationships.
Methods: Tuber number and TBP were characterized on three-dimensional fluid-attenuated inversion recovery MRI with an automated tuber segmentation program. Seizure histories and EEG recordings were obtained. Intelligence equivalents were determined and an individual cognition index (a marker of cognition that incorporated multiple cognitive domains) was calculated.
Results: In our sample of 61 patients with TSC, TBP was inversely related to the age at seizure onset and to the intelligence equivalent and tended to be inversely related to the cognition index. Further, a younger age at seizure onset or a history of infantile spasms was related to lower intelligence and lower cognition index. In a multivariable analysis, only age at seizure onset and cognition index were related.
Conclusions: Our systematic analysis confirms proposed relationships between tuber load, epilepsy and cognitive function in tuberous sclerosis complex (TSC), but also indicates that tuber/brain proportion is a better predictor of cognitive function than tuber number and that age at seizure onset is the only independent determinant of cognitive function. Seizure control should be the principal neurointervention in patients with TSC.
SOX1 antibodies are markers of paraneoplastic Lambert-Eaton myasthenic syndrome Comments Off
Background/Objective: We reported that 43% of patients with Lambert–Eaton myasthenic syndrome (LEMS) and small cell lung cancer (SCLC) had an antibody called anti-glial nuclear antibody (AGNA), defined by the immunoreaction with the nuclei of the Bergmann glia of the cerebellum. This study was undertaken to identify the antigen recognized by AGNA and to confirm the association with paraneoplastic LEMS in a larger series.
Methods: We probed a fetal brain cDNA library with AGNA-positive sera. The presence of antibodies against the isolated antigen was detected by immunoblot of phage plaques from two positive clones. We studied 105 patients with LEMS (55 with SCLC), 50 with paraneoplastic neurologic syndromes, SCLC, and Hu antibodies, and 50 with only SCLC.
Results: Probing of the fetal brain expression library with AGNA sera resulted in the isolation of SOX1, a highly immunogenic tumor antigen in SCLC. IgG eluted from SOX1 clones produced the same cerebellar immunoreactivity as of AGNA sera. SOX1 antibodies were present in 64% of patients with LEMS and SCLC but in none of the 50 with idiopathic LEMS (p < 0.0001). Compared with paraneoplastic LEMS, the frequency of SOX1 antibodies was significantly lower in patients with Hu antibodies (32%, p = 0.002) and in those with only SCLC (22%).
Conclusions: SOX1 is the antigen recognized by anti-glial nuclear antibody–positive sera. The detection of SOX1 antibodies in patients with Lambert–Eaton myasthenic syndrome (LEMS) predicts the presence of small cell lung cancer and may be used to follow more closely those LEMS patients with no evidence of cancer at the initial workup.
Paraoxonase 1 (PON1) organophosphate hydrolysis is not reduced in ALS Comments Off
Objective: Four recent studies report a genetic association of the paraoxonase locus with sporadic amyotrophic lateral sclerosis (ALS). We tested the hypothesis that this association correlates with functional changes in paraoxonase 1 (PON1, MIM 168820).
Methods: Sera from 140 ALS participants; 153 age-, race-, and sex-matched controls; and 30 matched CSF samples were tested for paraoxonase, diazoxonase, and arylesterase activities. Participants with ALS were genotyped using tagging single nucleotide polymorphisms across the PON locus. Survival data and enzyme activity were correlated with genotype.
Results: There was a trend toward increased paraoxonase activity in ALS compared with controls (mean control paraoxonase 701.9 ± 469.7 U/L, mean ALS 792.5 ± 574.1 U/L; p = 0.066 after correction) which correlated with increased frequency of the homozygous arginine (RR) variant of PON1Q192R (p = 0.004). There was no significant difference in PON1 protein levels, or arylesterase or diazoxonase activities. Organophosphate hydrolysis rates had no effect on ALS survival.
Conclusions: Contrary to expectations, PON1 protein, paraoxonase, diazoxonase, and arylesterase activities were not reduced in amyotrophic lateral sclerosis (ALS). The increase in PON1R192 frequency in ALS in our study supports previous genetic susceptibility studies. Our findings suggest that the influence of PON1 polymorphisms on ALS susceptibility is not due to reduced organophosphate hydrolysis.
Association of gait and balance disorders with age-related white matter changes: The LADIS Study Comments Off
Objective: In the Leukoaraiosis and Disability (LADIS) Study, 11 European centers are evaluating the role of age-related white matter changes (ARWMC) as an independent determinant of the transition to disability in the elderly (65 to 84 years). We aimed at determining the influence of ARWMC on different objective measures of gait and balance.
Methods: Six hundred thirty-nine nondisabled individuals were prospectively enrolled and are being followed-up for 3 years. Subjects are graded in three standardized categories of ARWMC (mild, moderate, and severe) according to central MRI reading. Quantitative tests of gait and balance include the Short Physical Performance Battery (SPPB; range: 0 [poor] to 12 [normal]), a timed 8-m walk, and a timed single leg stance test.
Results: In cross-sectional analysis, deficiencies in gait and balance performance were correlated with the severity of ARWMC (SPPB: 10.2 ± 2.1 in the mild, 9.9 ± 2.0 in the moderate, 8.9 ± 2.6 in the severe group; p < 0.001). Walking speed correlated with the severity of ARWMC (1.24 ± 0.28 m/second in the mild, 1.18 ± 0.32 m/second in the moderate, and 1.09 ± 0.31 m/second in the severe group; p < 0.001). Balance was best in individuals with mild ARWMC (single leg stance time: 18.9 ± 10.8 seconds) compared with moderate and severe ARWMC (16.4 ± 10.8 and 13.6 ± 11.2 seconds) (p < 0.001). Physically inactive individuals had a higher risk of a pathologic SPPB score (moderate vs mild ARWMC: odds ratio 1.60, 95% CI 1.02 to 2.52; severe vs mild ARWMC: odds ratio 1.75, 95% CI 1.09 to 2.80).
Conclusions: Our findings support a strong association between the severity of age-related white matter changes and the severity of gait and motor compromise. Physical activity might have the potential to reduce the risk of limitations in mobility.
Bacterial and fungal meningitis in patients with cancer Comments Off
Objective: To analyze cases of bacterial and fungal meningitis in patients with cancer.
Methods: Retrospective chart review from 1993 to 2004 was performed of patients with cancer at our institution who had positive CSF bacterial or fungal culture.
Results: We identified 312 positive CSF cultures representing 175 unique presentations. Ninety-six cultures were deemed contaminants, leaving 79 cultures for analysis in 77 patients; 78% had prior neurosurgery. Organisms included 68% Gram-positive cocci, 10% Gram-positive bacilli, 14% Gram-negative bacilli, 7% Cryptococcus, and 1% C albicans. None had N meningitidis or H influenza. Two patients each had S pneumoniae or L monocytogenes. Five percent of presentations demonstrated the triad of fever, nuchal rigidity, and mental status changes. Seventy-five percent of presentations demonstrated CSF pleocytosis (≥10). Median CSF WBC count was 74 cells/mm3. CSF protein was elevated and glucose was depressed in 71%. In neutropenic patients (n = 6), 4 had 0 to 1 CSF WBC/mm3, and 2 had normal CSF. VP shunt infections were more likely to present with mental status changes. Thirty day mortality was 13%.
Conclusions: Patients with cancer do not manifest symptoms of meningitis as often as patients without cancer and display a very different set of CSF organisms compared to a general population. The CSF inflammatory response is muted in patients with cancer with meningitis. Most patients with cancer with meningitis have had prior neurosurgery. Additionally, the organisms causing meningitis in the cancer population have shifted over time, with a decline in the organisms which typically infect immunocompromised hosts and an increase in Gram-positive infections.
Diffusion tensor imaging of acute mild traumatic brain injury in adolescents Comments Off
Background: Despite normal CT imaging and neurologic functioning, many individuals report postconcussion symptoms following mild traumatic brain injury (MTBI). This dissociation has been enigmatic for clinicians and investigators.
Methods: Diffusion tensor imaging tractography of the corpus callosum was performed in 10 adolescents (14 to 19 years of age) with MTBI 1 to 6 days postinjury with Glasgow Coma Scale score of 15 and negative CT, and 10 age- and gender-equivalent uninjured controls. Subjects were administered the Rivermead Post Concussion Symptoms Questionnaire and the Brief Symptom Inventory to assess self-reported cognitive, affective, and somatic symptoms.
Results: The MTBI group demonstrated increased fractional anisotropy and decreased apparent diffusion coefficient and radial diffusivity, and more intense postconcussion symptoms and emotional distress compared to the control group. Increased fractional anisotropy and decreased radial diffusivity were correlated with severity of postconcussion symptoms in the MTBI group, but not in the control group.
Conclusions: In adolescents with mild traumatic brain injury (MTBI) with Glasgow Coma Scale score of 15 and negative CT, diffusion tensor imaging (DTI) performed within 6 days postinjury showed increased fractional anisotropy and decreased diffusivity suggestive of cytotoxic edema. Advanced MRI-based DTI methods may enhance our understanding of the neuropathology of TBI, including MTBI. Additionally, DTI may prove more sensitive than conventional imaging methods in detecting subtle, but clinically meaningful, changes following MTBI and may be critical in refining MTBI diagnosis, prognosis, and management.