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Abnormal muscle responses in hemifacial spasm: F waves or trigeminal reflexes?

OBJECTIVE: In patients with hemifacial spasm (HFS), abnormal muscle responses (AMR) are frequently present. The objective of this study was to investigate whether the afferent input of AMR is mediated by antidromic facial nerve stimulation or orthodromic trigeminal nerve stimulation. METHODS: AMR in the orbicularis oris muscle were recorded in 28 patients with HFS. When AMR were present, they were recorded after subthreshold stimulation of the facial nerve and weak stimulation delivered to the skin. RESULTS: AMR were recordable in 24 (86%) of the patients, and usually consisted of the early constant component (mean onset latency, 10.0 ms) and late variable component (35.3 ms), similar to R1 and R2 of the blink reflex. The early or late components of AMR, or both, were frequently elicited after subthreshold stimulation of the facial nerve (43%) and skin stimulation (88%). CONCLUSIONS: AMR are likely to be mediated by trigeminal afferent inputs, rather than antidromic activation of the facial nerve, and are a type of trigeminal reflex.

Adult↗

Assessment of pupillary light reflex latency and darkness adapted pupil size in control subjects and in diabetic patients with and without cardiovascular autonomic neuropathy.

Increased pupillary light reflex latencies were found more often than a reduced darkness pupil size in diabetic patients with and without abnormal cardiovascular reflexes. This finding suggests that parasympathetic pupillary dysfunction precedes sympathetic pupillary denervation in diabetic autonomic neuropathy.

Adolescent↗

Subnormal pancreatic polypeptide and epinephrine responses to insulin-induced hypoglycemia identify patients with insulin-dependent diabetes mellitus predisposed to develop overt autonomic neuropathy.

Sixteen patients with insulin-dependent diabetes mellitus with no current evidence of autonomic dysfunction underwent an insulin tolerance test during which plasma pancreatic polypeptide and epinephrine responses were determined. Compared to 11 age- and weight-matched nondiabetic volunteers, 9 diabetic subjects had subnormal plasma pancreatic polypeptide responses (n = 6) or plasma epinephrine responses (n - 8). When autonomic function was reassessed 2 to 3 years later by standard cardiovascular reflex tests and clinical examination, 8 of 9 diabetic subjects with subnormal hormonal responses to hypoglycemia developed either abnormal cardiovascular reflexes (6 of 9) or overt symptoms consistent with diabetic autonomic neuropathy (6 of 9), whereas none of the subjects with previously normal plasma pancreatic polypeptide and epinephrine responses did (P less than 0.01). Diminished pancreatic polypeptide and epinephrine responses to hypoglycemia can predict the development of overt autonomic neuropathy in patients with insulin-dependent diabetes mellitus; identification of patients with a predilection to develop autonomic neuropathy may permit earlier treatment.

Adult↗

Neuropathy and mortality in diabetes: influence of pancreas transplantation.

We collected information on patient status and cause of death for 545 insulin-dependent diabetic subjects who had cardiorespiratory reflex and nerve conduction tests performed to determine if presence and severity of autonomic and somatic neuropathy is associated with mortality and if a functioning pancreas transplantation (PTx) influences mortality. Follow-up was 12-138 months. Abnormal cardiorespiratory reflexes were present in 417 patients and there was abnormal nerve conduction in 392 patients. Mortality rates for patients with abnormal tests were higher (P < 0.0001) than for patients with normal tests. A total neuropathy score that included cardiorespiratory and nerve conduction test scores predicted survival better than separate scores. Patients with moderate neuropathy, but not those with severe neuropathy, who retained a functioning PTx, had longer survival times than patients whose PTx failed in the first 3 months. Considering only patients transplanted after 1985, those with moderate neuropathy who retained a functioning PTx had even longer survival times than nontransplanted patients.

Adult↗

Origin of symptoms in chronic heart failure.

Skeletal muscle abnormalities are highly prevalent in chronic heart failure and are associated with an increase in the ergoreflex, a muscle reflex stimulated by work done. Stimulation of the ergoreflex results in increased ventilation and contributes to the increased sympathetic activation of the heart failure syndrome. The origin of the skeletal myopathy is related to a chronic imbalance between catabolic and anabolic processes, presumably as a consequence of chronic haemodynamic stress. Symptoms arise from the skeletal myopathy, causing the sensation of fatigue and contributing to the sensation of breathlessness as the myopathy affects respiratory muscle. Ergoreflex activation causes a greater ventilatory response to exercise than normal, contributing to the sensation of breathlessness.

Chronic Disease↗

Congenital rubella syndrome: function of equilibrium of 80 cases with deafness.

The equilibrium function of 80 deaf children with congenital rubella syndrome, aged 12, was examined by the caloric and righting reflex tests. Of these 80 children, 24 (30%) had vestibular hypofunction, 6 (7.5%) were suspect, and the remaining 50 (62.5%) were normal. Of all 160 ears tested, vestibular hypofunction was proven in 21.3%, suspect in 5.6%, and normal in the rest. There was no correlation between the incidence of vestibular hypofunction and the degree of hearing loss. Of the 30 children with vestibular hypofunction, 14 (47%) showed a normal righting reflex, suggesting the working of a compensatory mechanism. Of the 50 children with normal caloric responses, 26% revealed an abnormal righting reflex. This discrepancy might be accounted for by an otolith organ injury or minimal brain dysfunction.

Caloric Tests↗

[Subependymal/intraventricular hemorrhage in preterm newborn infants. Neurodevelopmental course during the first year of life].

Subependymal/intraventricular hemorrhage (SE/IVH) is the most frequently encountered type of hemorrhage in the neonatal period. Premature infants often develop SE/IVH which remains is one of most serious neonatal events. We studied a group of 96 premature newborn infants: half of which were diagnosed with SE/IVH. We evaluated the babies at six and 12 months of age which++ a battery of neurobehavioral exams, including neurological, psychological, motor an audiological test. In 52 of infants with SE/IVH showed some type of neurobehavioral abnormality, compared with 13% of non-SE/IVH infants. In 56% of SE/IVH infants had neurological abnormalities at 12 months (P < 0.0001) difference with non-SE/IVH), predominantly in areas of muscle tone and reflex. Motor abnormalities were encountered in 42% of SE/IVH children, and in 4% of non-SE/IVH children at 12 months. Psychometric abnormalities at 12 months were noted in 53% of the SE/IVH group. Hypocusis were noted in 38% of the SE/IVH group and in 15% of the non-SE/IVH group.

Cerebral Hemorrhage↗

Abnormal perception of the tonic vibration reflex in idiopathic focal dystonia.

Although the pathophysiological basis of idiopathic focal dystonia (IFD) remains unclear, we recently reported abnormal perception of the tonic vibration reflex (TVR) in the biceps brachii in IFD. In this study we examined whether the abnormality affects muscles other than the biceps brachii. A 100-Hz vibration stimulating predominantly the muscle spindle afferent was transcutaneously applied to one muscle tendon of the triceps brachii, the wrist extensor and flexor muscles in 29 subjects with IFD (18 with torticollis, 9 with writer's cramp, 2 with blepharospasm) and 15 control subjects. The blindfolded subjects were instructed to copy any perceived movement with the opposite tracking arm. The elbow or wrist angle changes were quantified electronically. The TVR and subjects' perception of the TVR were evaluated by angle movements of the vibrated joint and of the tracking joint, respectively. Perception of the TVR was significantly reduced in dystonic subjects at both elbow and wrist joints, while magnitude of the TVR did not differ between the two groups. Abnormal central perception of the TVR is a feature of IFD, suggesting a widespread involvement of abnormal muscle spindle afferent processing in IFD.

Adult↗

Antinociceptive reflex alteration in acute posttraumatic headache following whiplash injury.

Brainstem-mediated antinociceptive inhibitory reflexes of the temporalis muscle were investigated in 82 patients (47 F, 35 M, mean age 28.3 years, SD 9.4) with acute posttraumatic headache (PH) following whiplash injury but without neurological deficits, bone injury of the cervical spine or a combined direct head trauma on average 5 days after the acceleration trauma. Latencies and durations of the early and late exteroceptive suppression (ES1 and ES2) and the interposed EMG burst (IE) of the EMG of the voluntarily contracted right temporalis muscle evoked by ipsilateral stimulation of the second and third branches of the trigeminal nerve were analyzed and compared to a cohort of 82 normal subjects (43 F, 39 M, mean age 27.7 years, SD 7.1). Highly significant reflex alterations were found in patients with PH with a shortening of ES2 duration with delayed onset and premature ending as the primary parameter of this study, a moderate prolongation of ES1 and IE duration and a delayed onset of IE. The latency of ES1 was not significantly changed. These findings indicate that acute PH in whiplash injury is accompanied by abnormal antinociceptive brainstem reflexes. We conclude that the abnormality of the trigeminal inhibitory temporalis reflex is based on a transient dysfunction of the brainstem-mediated reflex circuit mainly of the late polysynaptic pathways. The reflex abnormalities are considered as a neurophysiological correlate of the posttraumatic (cervico)-cephalic pain syndrome. They point to an altered central pain control in acute PH due to whiplash injury.

Adolescent↗

The tendon reflexes in the electrodiagnosis of sciatica.

In order to determine the diagnostic value of the electromyographically tested tendon reflexes (ETR) in lumbosacral radiculopathies, we compared the latency and amplitude of the knee (EKTR) and Achilles tendon reflex (EATR) to their clinical testing and to the EMG and H reflex values in 200 non selected patients (126 men, 74 women) aged 24-68 years (48.6 +/- 9.4). The control group was composed of 50 healthy volunteers (28 men, 22 women) aged 25-60 yrs (44 +/- 8.5). The combined electrophysiological reflex examination was abnormal in 45% of the affected limbs, being the most frequent pathological finding. EMG was abnormal in 34.4% and H reflex in 30.4% of the affected limbs. Furthermore, the EATR taken separately was more sensitive than the H-reflex (42.8% versus 30.4%). Pathological ETR were elicited in a considerable percentage of the clinically normal tendon reflexes (TR): 7.3% of the knee and 14.1% of the Achilles TR. On the other hand 65% of the clinically absent ATR were recorded electrically producing abnormally low and delayed muscle evoked potentials.

Adult↗

Cochlear and vestibular functions of the rat after obliteration of the endolymphatic sac.

A combined morphological and physiological study on the effect of saccus obliteration on the cochlea and the vestibular labyrinth of the rat is presented. Endolymphatic hydrops was successfully induced in 49% of the animals. It was frequently associated with fistulae of the membranous wall and degenerative changes in the organ of Corti and spiral ganglion. In hydropic ears electrocochleography revealed a CAP threshold increase only in those cases where hydrops was associated with loss of hair cells and ganglion cells. In two of these animals also an increased negative SP was present. Static otolith reflexes were found to be normal in all hydropic ears despite severe lesions of the saccule in some of these. Abnormal canal reflexes measured by electronystagmography and cupulometry were established in animals with hydrops of the semicircular canals and in one animal with a fistula of the saccule.

Animals↗

Reliability of observational measures of the Movement Assessment of Infants.

This study was conducted to examine the reliability of the Movement Assessment of Infants (MAI), a recently published neuromotor assessment tool. Interobserver and test-retest reliability data were collected on 27 full-term and 26 preterm 4-month-old infants. Reliability coefficients (Pearson r) were calculated for both the total-risk scores and the section-risk scores on the MAI. The total-risk score was calculated by summing the questionable or abnormal ratings on each of the 65 test items. For each of the four sections of the test, tone, primitive reflexes, automatic reactions, and volitional movement, an individual section-risk score was computed in a similar manner. Fair reliability was demonstrated for the total-risk scores (interobserver: r = .72; test-retest: r = .76). Section-risk score coefficients yielded a wide range of values for both interobserver and test-retest reliabilities (poor to good reliability). These measures provide needed technical data for therapists using this test and will assist the authors of the MAI in their attempts to improve the clinical validity of this assessment tool.

Evaluation Studies as Topic↗