Parkinsonism: Electromyographic Studies of Monosynaptic Reflex

Ioku, M; Ribera, Victor A.; Cooper, Irving S.; Matsouka, Shigeata

doi:10.1126/science.150.3702.1472

Cited by 12 publications

(9 citation statements)

References 6 publications

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“…The findings indicate that recovery of excitability of the alpha motoneurone pool occurs more rapidly in patients with Parkinson's disease and is consistent with the presence of increased alpha motoneurone excitability in these patients. Denny-Brown (1968) concluded from observations in man and experimental animals that there was alpha motoneurone hyperactivity in Parkinson's disease, and other workers have reached similar conclusions Ward, 1962, 1963;Ioku et al, 1965;Olsen and Diamantopoulos, 1967;Takamori, 1967;Yap, 1967).…”

Section: Recovery Of H Reflex Before Treatment Withmentioning

confidence: 79%

“…Amplitude, OS mV. workers as a means of studying the excitability of the alpha motoneurone pool in a number of different conditions, including spasticity, Parkinson's disease, and cerebellar disorders (Magladery, Teasdall, Park, and Languth, 1952;Ioku, et al, 1965;Olsen and Diamantopoulos, 1967;Takamori, 1967;Yap, 1967;McLeod, 1969). were employed.…”

Section: Recovery Of H Reflex Before Treatment Withmentioning

confidence: 99%

“…Although some evidence suggests that it results from increased fusimotor activity (Rushworth, 1960), a number of workers have concluded that there is hyperactivity of the alpha motoneurones (Ioku, Ribera, Cooper, and Matsouka, 1965;Olsen and Diamantopoulos, 1967;Takamori, 1967;Yap, 1967;Denny-Brown, 1968). The aim of the present investigation was to investigate the effect of L-dopa on alpha motoneurone excitability in a group of patients with Parkinsonian rigidity by means of H reflex studies.…”

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confidence: 99%

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H reflex studies in patients with Parkinson's disease

McLeod

Walsh

1972

Journal of Neurology, Neurosurgery & Psychiatry

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SUMMARY The H reflex was studied in 13 patients with Parkinson's disease, and the results compared with those obtained in 22 control subjects. Pairs of identical stimuli near threshold intensity were delivered and the unresponsive period and time course of recovery of the amplitude of the H reflex were determined. The duration of the unresponsive period was significantly shorter in the patients with Parkinson's disease. In 10 patients the studies were repeated after treatment with L-dopa for six months. There was a significant increase in the period of unresponsiveness of the H reflex after treatment. The findings suggest that there is an increase in alpha motoneurone excitability in Parkinson's disease, and that it is reduced by treatment with L-dopa.The pathophysiology of Parkinsonian rigidity is uncertain. Although some evidence suggests that it results from increased fusimotor activity (Rushworth, 1960), a number of workers have concluded that there is hyperactivity of the alpha motoneurones (Ioku, Ribera, Cooper, and Matsouka, 1965;Olsen and Diamantopoulos, 1967;Takamori, 1967;Yap, 1967; DennyBrown, 1968). The aim of the present investigation was to investigate the effect of L-dopa on alpha motoneurone excitability in a group of patients with Parkinsonian rigidity by means of H reflex studies. METHODSThirteen subjects with Parkinson's disease, whose ages ranged from 57 to 65 years, were studied. Of these 10 received treatment with L-dopa, and studies were performed before and at six months after commencement of treatment. In all cases, rigidity and akinesia were the prominent clinical features.Twenty-two control subjects, whose ages ranged from 16 to 73 years, were studied previously and the results reported (McLeod, 1969).H REFLEX STUDIES The technique and apparatus employed were identical with those previously described (McLeod, 1969 A conditioning shock of intensity less than 1-1 times threshold for the H reflex was followed at intervals ranging from 2 msec to 1 sec by an identical test stimulus. Ten seconds were allowed to elapse between each pair of stimuli. The ratio of the peakto-peak amplitude of the H wave after the test volley to that of the H wave after the conditioning volley was calculated at each interval of time and a recovery curve plotted. RESULTS RECOVERY OF H REFLEX BEFORE TREATMENT WITHL-DOPA Recovery of the H reflex after a near threshold conditioning volley was plotted in 13 patients with Parkinsonian rigidity. The mean curve is shown in Fig. 1

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Section: Recovery Of H Reflex Before Treatment Withmentioning

confidence: 79%

Section: Recovery Of H Reflex Before Treatment Withmentioning

confidence: 99%

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confidence: 99%

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H reflex studies in patients with Parkinson's disease

McLeod

Walsh

1972

Journal of Neurology, Neurosurgery & Psychiatry

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“…A valid comparison cannot be made with recovery curves obtained by investigators who have used stimuli of greater intensity (McComas and Payan, 1966;Takamori, 1967) or who have not specified the strength of stimulus (Magladery et al, 1952;Ioku et al, 1965). The early phase of facilitation after a conditioning volley is presumably due to recruitment of motoneurones which have been subliminally excited, as postulated by Magladery and co-workers (1952).…”

Section: Discussionmentioning

confidence: 96%

H reflex studies in patients with cerebellar disorders.

McLeod¹

1969

Journal of Neurology, Neurosurgery & Psychiatry

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“…The refractory period and subsequent recovery of the H reflex is abnormal in Parkinsonism but the physiological significance of this phenomenon is obscure (Ioku, Ribera, Cooper, and Matsouka, 1965;Olsen and Diamantopoulos, 1967;Yap, 1967).…”

Section: Tonic Activation: Resultsmentioning

confidence: 99%

Dynamic spindle reflexes and the rigidity of Parkinsonism

McLellan

1973

Journal of Neurology, Neurosurgery & Psychiatry

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SUMMARY The effects of stimulating the reflex arc from dynamic spindle endings were examined in patients with the rigidity of Parkinsonism and in control subjects. The arc was activated phasically by a tendon tap and by electrical stimulation in 15 patients. The effect of reinforcement by Jendrassik's manoeuvre was observed. The response to phasic activation indicated central facilitation of the reflex loop in the patients with Parkinsonism, with a concurrent decrease in fusimotor drive to dynamic spindles. These abnormalities could not be correlated with the severity of the patients' rigidity, and they did not alter when the rigidity was reduced by levodopa. The effect of activating dynamic spindle endings tonically by vibration at 50 Hz was also examined. The reflex contraction of the biceps and triceps muscles in response to vibration was found to be increased in 24 patients with rigidity compared with 24 control subjects. Patients with severe rigidity developed a more powerful contraction in response to vibration than patients with mild rigidity. The response to vibration was reduced by treatment with levodopa but the amount of this reduction could not be correlated with changes in the patients' rigidity.Rigidity is a clinical term used to indicate an increased resistance of muscle to passive stretch, the resistance being approximately constant throughout the range of stretching. DennyBrown (1960) has pointed out that when a rigid limb is fully supported and the patient relaxed, the rigidity disappears and unimpaired passive movement is possible in either direction within a range of 5-10°. Movement of a larger range sets up a contraction in the stretched muscle which is maintained as the movement continues, showing that rigidity is a stretch reflex activated by sensory receptors in the muscle. Sensory nerve fibres from primary muscle spindle organs are known to connect monosynaptically with alpha motoneurones serving related extrafusal muscle fibres. It is therefore possible that activation of primary spindle organs initiates the reflex contraction responsible for the phenomenon of rigidity. This would imply abnormal functioning of the reflex loop and the purpose of the present 1 Present address:

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Parkinsonism: Electromyographic Studies of Monosynaptic Reflex

Cited by 12 publications

References 6 publications

H reflex studies in patients with Parkinson's disease

H reflex studies in patients with Parkinson's disease

H reflex studies in patients with cerebellar disorders.

Dynamic spindle reflexes and the rigidity of Parkinsonism

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