Handwriting and speech changes across the levodopa cycle in Parkinson's disease.

Levodopa treatment is used to reduce rigidity and bradykinesia in Parkinson's disease (PD). This study tracked the handwriting and speech performance of 10 PD patients at 30-minute intervals across one levodopa drug cycle to evaluate levodopa-related changes in temporal and spatial measures that are assumed to correspond to changes in rigidity and bradykinesia. The handwriting measures included l and e upstroke duration and size. The speech measures included duration of the vowels /i/, /u/, /ae/, and /[symbol: see text]/ and the quadrilateral area produced by these vowels, and the slope of the diphthong /aI/. Levodopa significantly improved handwriting upstroke duration but not upstroke size. Speech measures did not show a significant trend across the levodopa cycle. The results suggest that upstroke duration is sensitive to the presumed effects of levodopa and that handwriting analysis may hold promise in helping to estimate an optimum levodopa regimen for PD patients.

Neural dynamics of short and medium-term motor control effects of levodopa therapy in Parkinson's disease.

A neural network model of movement control in normal and Parkinson's disease (PD) conditions is proposed to simulate the time-varying dose-response relationship underlying the effects of levodopa on movement amplitude and movement duration in PD patients. Short and long-term dynamics of cell activations and neurotransmitter mechanisms underlying the differential expression of neuropeptide messenger RNA within the basal ganglia striatum are modeled to provide a mechanistic account for the effects of levodopa medication on motor performance (e.g. the pharmacodynamics). Experimental and neural network simulation data suggest that levodopa therapy in Parkinson's disease has differential effects on cell activities, striatal neuropeptides, and motor behavior. In particular, it is shown how dopamine depletion in the striatum may modulate differentially the level of substance P and enkephalin messenger RNA in the direct and indirect basal ganglia pathways. This dissociation in the magnitude and timing of peptide expression causes an imbalance in the opponently organized basal ganglia pathways which results in Parkinsonian motor deficits. The model is validated with experimental data obtained from handwriting movements performed by PD subjects before and after medication intake. The results suggest that fine motor control analysis and network modeling of the effects of dopamine in motor control are useful tools in drug development and in the optimization of pharmacological therapy in PD patients.

Use of the modified barium swallow in the rehabilitation of the swallowing mechanism.

Swallowing is a rapid, dynamic and complex process. Surgical treatment of head and neck malignancies produces significant alterations in the swallowing mechanism. The modified barium swallow allows assessment of these physiologic and anatomic derangements in the postoperative patient. Small amounts of liquid barium, barium paste and a cookie coated with barium are ingested by the patient and the swallowing mechanism is recorded by videofluoroscopy. Unlike the routine barium swallow in which only the esophageal stage of swallowing is studied, using the modified barium swallow all four stages of swallowing are studied with particular emphasis on the oral and pharyngeal stages. Our experience with the modified barium swallow has shown it to be a valuable adjunct in the rehabilitation of the post-surgical patient allowing the otolaryngologist and speech pathologist to identify and modify swallowing abnormalities. Presentation of specific swallowing mechanism deficits as demonstrated using the modified barium swallow will be shown and appropriate therapeutic interventions discussed.