Biomedical subjects

Samer D Tabbal

Publications and source records attributed to Samer D Tabbal.

3 recordsLinked to original sources

PubMed2006

A rapid method for mass screening for parkinsonism.

Epidemiology studies of parkinsonism employ a variety of techniques for unbiased sampling of populations. No current method permits mass screening of all subjects in a population for parkinsonism by movement disorders specialists. We developed and piloted a new approach to facilitate accurate and efficient screening of large populations for diagnosis of parkinsonism and provide data on sensitivity and specificity. We evaluated 2081 welders referred for medical-legal screening. Subjects were video taped using a standardized protocol, and videos were rated on the Unified Parkinson's Disease Rating Scale motor subsection 3 (UPDRS3). A "video rater" viewed video tapes and entered ratings through a web-based database. An "in-person" examiner performed a UPDRS3 examination in a randomly selected subgroup of 48 workers drawn from the 2081. We developed quantitative diagnostic criteria for parkinsonism that established minimum diagnostic thresholds based upon UPDRS3 scores and compared these criteria with diagnosis by an in-person examiner. Specificity of these criteria compared to in-person examination was 91-100% but sensitivity was 56%. A threshold UPDRS3 score greater than nine provided 100% sensitivity and 81% specificity. Liberal criteria identified 266 (13.1%) subjects with probable parkinsonism and 220 (10.8%) subjects with definite parkinsonism. Conservative criteria identified 260 (12.8%) with probable parkinsonism and 122 (6%) with definite parkinsonism. Our screening method permits rapid assessment of parkinsonian signs. An absolute UPDRS3 score greater than nine provided the best combination of sensitivity and specificity for the diagnosis of parkinsonism, while quantitative exam-based criteria for cardinal parkinsonian signs maximized specificity. Parkinsonism as diagnosed by our criteria was common in this group of welders.

Female↗

PubMed2006

Relative risk of spread of symptoms among the focal onset primary dystonias.

Adult-onset primary torsion dystonia (PTD) may spread to multiple body parts, but the relative risk of spread by site of onset of dystonia has not been well characterized. We retrospectively identified 602 patients with PTD out of 1,500 dystonia patients in our electronic database and extracted age at onset, site of onset, family history, and spread. Survival analyses were performed for groups based on site of onset, and hazard ratios compared relative risk of spread across groups. Patients with adult-onset blepharospasm were more likely to spread (31% past the head) than those with dystonia starting in the neck (9%), larynx (12%), or upper extremities (16%). Hazard ratios proved that the blepharospasm group had the greatest relative risk of spread. The rate of spread after onset varied significantly between the different groups. Most spread occurred in the first 1 to 2 years after onset of blepharospasm, whereas the risk of spread was relatively constant over time in cervical and laryngeal dystonia. Different sites of onset of PTD confer different risks of spread, important for clinical prognosis. Different risks of spread may provide clues about underlying pathogenesis of adult-onset primary dystonias.

Adult↗

PubMed2006

Postural tremor suppression is dependent on thalamic stimulation frequency.

Deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) reduces tremor in people with essential tremor (ET), yet the dependence of tremor suppression on stimulation frequency remains unclear. To address this issue, we tested tremor suppression for three 15-second measurements during a variety of stimulation frequencies in 11 ET patients treated with VIM DBS. Stimulation frequencies at or above 100 Hz produced maximal benefit; higher frequencies provided no additional benefit. If this short-term measure predicts long-term response in routine activities at home, then this stimulation frequency setting will prolong battery half-life compared to higher frequency settings. These findings suggest that ET patients treated with VIM DBS may receive adequate benefit from stimulation frequencies about 100 Hz and this setting compared to commonly used higher settings will prolong battery life of surgically implanted pulse generators.

Aged↗