Dysphagia in Parkinson's disease.

Although dysphagia is an important symptom associated with prognosis in patients with Parkinson's disease (PD), dysphagia tends to be overlooked until swallowing difficulties reach an advanced phase. We assessed dysphagia with videofluoroscopic examination of swallowing in 31 patients with mainly mild or moderate PD. Swallowing problems were observed in the pharyngeal phase in 28 patients, oral phase in 19 patients, esophageal phase in 15 patients, and oral preparatory phase in 1 patient. Therefore, dysphagia in the pharyngeal phase was observed in almost all patients with mild or moderate PD. In contrast, no dysfunction was detected in most patients when screening was conducted via questionnaire or other methods. Assessment of clinical parameters in the present study suggests that latent swallowing dysfunction may be present even in the early disease stage in PD. A future prospective study to follow swallowing functions in a pre-symptomatic phase in PD would be fruitful to find whether swallowing dysfunction is one of the prodromal symptoms.

Can Awaji ALS criteria provide earlier diagnosis than the revised El Escorial criteria?

BACKGROUND: Recently, new electrophysiological ALS criteria incorporating fasciculation potentials (FPs) as evidence for lower motor neuron signs (Awaji Criteria (AC)) was proposed to provide earlier detection of early-stage ALS than revised El Escorial electrophysiological criteria (REEC). However, serial electrophysiological analysis is lacking to ascertain the original intention. The objective for this study was to elucidate whether electrophysiological criteria set for AC detects ALS earlier than REEC's counterpart in patients with ALS. METHODS: Of the 51 patients who were clinically suspected of ALS, 35 patients prospectively received serial electrophysiological studies every 3 months until (1) both electrophysiological AC and REEC criteria were met in more than two muscles representing both of the cervical and lumbosacral segments or (2) either clinically definite or clinically probable REEC criteria was met. The intervals were determined between the initial disease onset and when the respective electrophysiological criteria were met. RESULTS: Electrophysiological diagnostic criteria were met in 94.3% by AC and 40% by REEC at the initial visits. The intervals between the disease onset and the time of meeting the electrophysiological criteria were shorter in AC (mean: 9.0 months) than in REEC (mean: 15.2 months) (P<0.01). Eleven patients who met only AC electrophysiological criteria on the initial study subsequently met REEC electrophysiological criteria with the mean interval of 3.8 months. A higher percentage of bulbar-type ALS (83.3%) met AC than limb-onset ALS (43.4%) (P<0.05). FPs tended to be more frequently observed than fib/psw in the muscles outside the region of initial clinical onset. CONCLUSION: Electrophysiological criteria of AC were met earlier than that of REEC in ALS patients, especially in patients with bulbar onset. Early recognition of ALS by AC may allow effective therapeutic intervention in the early disease stage.

[Increased variability of membrane potentials in amyotrophic lateral sclerosis].

Amyotrophic lateral sclerosis (ALS) is characterized by increased excitability of motor neurons and early involvement of large motor fibers that have low electrical thresholds. Despite the advent of new techniques of threshold tracking, exploration of this abnormal excitability has not been straightforward, by tracking at the single target level as previous reported, because of the heterogeneous nature of the disease process among fibers that have variable thresholds. We have assessed different populations of motor axons by tracking at four different target response levels (10, 20, 40 and 60% of maximum compound muscle action potentials), and conducted multiple nerve excitability tests in 27 ALS patients and 23 control subjects. In normal controls, axons with low thresholds have the following characteristics compared to those with high thresholds: greater threshold reduction during depolarizing currents and smaller threshold increase to hyperpolarizing currents, reflecting the order of the fiber size. In contrast, ALS patients lacked these relationships, suggesting increased variability of axonal membrane potentials. Three ALS patients demonstrated changes in threshold electrotonus, consistent with overt membrane depolarization, as seen in ischemic nerves. The variability of motor nerve excitability accounts for fasciculations, confirms previously reported dysfunction of potassium channels, and suggests failure of Na(+)/K(+)pumps, possibly caused by mitochondrial dysfunctions at the early stage.

Utility of recovery cycle with two conditioning pulses for detection of impaired axonal slow potassium current in ALS.

OBJECTIVE: Slow potassium current (I(Ks)) is important in controlling nerve excitability and its impairment is known in various neurological diseases, including amyotrophic lateral sclerosis (ALS). I(Ks) gives rise to the late subexcitability phase of the recovery cycle, which can be amplified by the use of multiple conditioning pulses. The clinical utility of this technique has not previously been explored. METHODS: Nerve excitability tests, including recovery cycles with single and double conditioning pulses 4ms apart (RC and RC2, respectively) were performed in patients with ALS and control subjects. Late subexcitability values obtained by RC and RC2 were compared in both groups. RESULTS: RC2 was well tolerated in all the subjects. The threshold changes in late subexcitability by RC2 were greater than those by RC in both groups (mean (%): RC, 16.0/13.3; RC2, 34.9/29.4 (Control/ALS)). The ALS group showed lower threshold changes than controls by both methods. Statistical analysis between the ALS and control groups provided smaller P value by RC2 (P=0.018) than by RC (P=0.046). Also, RC2 provided non-significant, but slightly more distinguishing non-parametric rank analysis and greater Area Under the Curve (AUC) by Receiver Operating Characteristic (ROC). RC2 produced more identifiable single peak for late subexcitability than RC in an ALS patient whose late subexcitability was decreased. CONCLUSIONS: Two conditioning stimuli provide greater threshold change for late subexcitability and possibly clearer identification of a peak threshold change than conventional recovery cycle. The findings obtained by this new protocol reinforce the previously reported impairment of I(Ks) in ALS. SIGNIFICANCE: Amplification of I(Ks) by double conditioning pulses is applicable in humans and may help elucidating its clinical significance in pathophysiology in neurological diseases.