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PubMed1996

Prevalence and mechanisms of hearing loss in patients with resistance to thyroid hormone.

Hearing impairment was anecdotally reported in resistance to thyroid hormone (RTH), a condition caused by mutations in the beta-thyroid hormone receptor (beta TR) gene. Because of its ontogenic distribution in the cochlea, the beta TR may have a pivotal role in the development of auditory function. To assess the prevalence and mechanisms of hearing impairment in RTH, 82 RTH-positive (RTH+) patients and 55 unaffected relatives (RTH-) underwent systematic audiological examination, including puretone and speech reception thresholds, and tests studying middle ear (tympanometry and acoustic reflexes), cochlear (otoacoustic emissions), and retrocochlear integrity (brain stem auditory evoked potentials). Significant hearing loss was present in 21% of RTH+ patients vs. none in RTH- patients. More RTH+ patients had abnormal tympanometry (34% vs. 12%) and abnormal acoustic reflexes (39% vs. 19%). Isolated conductive deficit was found in 7 of 17 RTH+ patients with hearing loss, isolated sensorineural deficit in 7 cases, and mixed deficit in 3 cases. Cochlear dysfunction was found in 50% of all RTH+ patients, with or without hearing loss. Retrocochlear function was normal. No morphological cochlear abnormalities were detected on computed tomography of the temporal bone. In conclusion, hearing loss is a significant problem in RTH, with an equal frequency of conductive (probably related to the frequent ear infections) and sensorineural deficits. Abnormal otoacoustic emissions suggest that the mutant beta TR has a specific negative impact on cochlear function.

Adult↗
PubMed2005

Late-onset Friedreich ataxia: phenotypic analysis, magnetic resonance imaging findings, and review of the literature.

BACKGROUND: Friedreich ataxia (FA), the most common hereditary ataxia, is caused by pathological expansion of GAA repeats in the first intron of the X25 gene on chromosome 9. Since the discovery of the gene, atypical features are increasingly recognized in individuals with FA, and up to 25% of patients with recessive or sporadic ataxia do not fulfill the Harding or Quebec Cooperative Study on Friedreich's Ataxia criteria for FA. Late-onset FA (LOFA) is defined as onset after age 25 years. OBJECTIVES: To describe and further delineate the clinical and magnetic resonance imaging findings in patients with LOFA and to review the literature. DESIGN: Clinical evaluation and comparison of clinical data and investigations. SETTING: Ataxia clinics at UCLA and Cedars-Sinai Medical Center. PATIENTS: Thirteen patients with LOFA with 13 sex-matched and Inherited Ataxia Progression Scale-matched patients with typical FA. RESULTS: Gait and limb ataxias were seen in all the participants. Dysarthria, loss of vibration sense, and abnormal eye movements were also common in both groups. Patients with LOFA more often had lower limb spasticity (40% vs 0%; chi2 = 4.0; P = .04) and retained reflexes (46.1% vs 7.7%; chi2 = 3.46; P = .05). They had no complaint of sphincter disturbances, and there was no evidence of cardiomyopathy on echocardiograms (chi2 = 4.0; P = .04). Five of 9 patients with LOFA had cerebellar atrophy on neuroimaging. CONCLUSIONS: Patients with gait and limb ataxias, dysarthria, loss of vibration sense, and fixational instability after age 25 years should be considered for molecular testing for GAA expansion in the FA gene. In contrast to previous studies, cerebellar vermian atrophy is not an uncommon finding.

Adult↗
PubMed1979

A new acoustic reflex pattern.

A new crossed-vs-uncrossed acoustic reflex pattern has been observed in four patients with retrocochlear disorder. The new reflex pattern is characterized by a unique "uni-box" configuration. Reflexes are abnormal with sound to the affected ear on crossed stimulation only. In one additional patient, a variation of the uni-box pattern was found on suprathreshold reflex amplitude measures. WE observed a large ear difference between reflex amplitude functions in the crossed condition, but not in the uncrossed condition. This observation suggests that reflex amplitude measures may be a valuable addition to threshold measures in some patients.

Adolescent↗
PubMed2007

Neurophysiological evaluation of trigeminal and facial nerves in patients with chronic inflammatory demyelinating polyneuropathy.

Cranial neuropathy is clinically uncommon in patients with chronic inflammatory demyelinating polyneuropathy (CIDP), but there is little information on the neurophysiological examination of cranial nerve involvement. To determine the incidence of trigeminal and facial nerve involvement in patients with CIDP, the direct response of the orbicularis oculi muscle to percutaneous electric stimulation of the facial nerve and the blink reflex (induced by stimulation of the supraorbital nerve) were examined in 20 CIDP patients. The latency of the direct response was increased in 12 patients (60%) and an abnormal blink reflex was observed in 17 patients (85%). There was no correlation between electrophysiological findings and the latencies of the direct and R1 responses and disease duration or clinical grade in CIDP patients. Nevertheless, the prevalence of subclinical trigeminal and facial neuropathy is extremely high in patients with CIDP when examined by neurophysiological tests.

Action Potentials↗
PubMed2001

Atlas hypoplasia manifesting as myelopathy in a child--case report.

A 14-year-old Japanese boy presented with myelopathy due to atlas hypoplasia with complete posterior arch. Decompressive laminectomy of the atlas produced good neurological recovery, and follow-up T2-weighted magnetic resonance imaging showed disappearance of spinal cord edema. Congenital atlas stenosis may be symptomatic even in children, with no accompanying cervical spondylotic change. Such cases have previously occurred only in Asian adults. A radiological study of the patient's brother showed median cleft formation of the posterior arch of atlas, indicative of a wide spectrum of atlas anomalies and a possible genetic relationship between these anomalies.

Adolescent↗
PubMed1995

Prospective follow-up of primitive reflex profiles in high-risk infants: clues to an early diagnosis of cerebral palsy.

To clarify reflex profiles in the first year of life in connection with categories of neurologic abnormality, eight primitive reflexes (i.e., the palmar grasp reflex, the plantar grasp reflex, the Galant response, the asymmetric tonic neck reflex, the suprapubic extensor reflex, the crossed extensor reflex, the Rossolimo reflex, and the heel reflex) were prospectively examined in 204 high-risk infants, of whom 58 developed cerebral palsy, 22 had developmental retardation, and 124 were normal at follow-up examination at 2 years of age. The change in the retention time of reflex activity for each of these reflexes was characteristic for each category or type of neurologic abnormality: retention of palmar grasp reflex, suprapubic extensor reflex, crossed extensor reflex, Rossolimo reflex, and heel reflex in spastic cerebral palsy, as well as retention of plantar grasp reflex, Galant reflex, and asymmetric tonic neck reflex in athetoid cerebral palsy and somewhat weaker retention of these reflexes in developmental retardation (statistical significance P < .001 compared with normally developed patients). These characteristic changes imply that a presumptive diagnosis can be made in neurologically high-risk infants by examination of the primitive reflexes, which are of specific significance among the other neurologic criteria within the first year of life.

Cerebral Palsy↗
PubMed1995

Hypertensive encephalopathy after bilateral carotid endarterectomy.

BACKGROUND: Hypertension occurs frequently after carotid endarterectomy and may lead to cerebral vascular complications and myocardial infarction. Its pathophysiology has recently been related to surgically induced damage of carotid baroreceptors. CASE DESCRIPTION: A 45-year-old normotensive man with no history of epilepsy was admitted 3 weeks after bilateral carotid endarterectomy for severe repetitive paroxysmal headaches, vomiting, and agitation that were closely associated with attacks of marked hypertension. During one of these attacks, he had a grand mal seizure. Plasma catecholamine levels during hypertensive attacks were highly elevated despite the absence of pheochromocytoma, reflecting abnormalities in baroreceptor sensitivity that lead to unrestrained activation of the central sympathetic nervous system. Heart rate response to Valsalva maneuver showed suppression of the usual tachycardia, indicating baroreceptor reflex insensitivity. CONCLUSIONS: We report the first case of hypertensive encephalopathy associated with baroreflex failure syndrome after bilateral carotid endarterectomy. The role of blood pressure monitoring may be critical in revealing carotid baroreceptor insensitivity in such clinical settings.

Baroreflex↗
PubMed1982

Conduction abnormalities of the facial and trigeminal nerves in polyneuropathy.

Facial and trigeminal nerve involvement in polyneuropathy was assessed by the evoked action potential of the orbicularis oculi muscle following direct stimulation of the facial nerve (direct response) and the two component blink reflex elicited by stimulation of the trigeminal nerve (R1 and R2). The latencies of the direct and R1 responses were increased substantially in the Guillain-Barré syndrome (GBS), chronic inflammatory polyneuropathy (CIPN), and hereditary motor and sensory neuropathy (HMSN Type I), and to a much lesser degree in diabetic polyneuropathy (DPN). The study was normal with rare exceptions in the Fisher syndrome (FS) and HMSN Type II. The latency ratio of R1 to the direct response showed a mild increase in GBS, a moderate decrease in CIPN and HMSN Type I, and a mild decrease in DPN. We conclude that these simple electrophysiologic techniques can provide useful, objective information in determining the degree and distribution of cranial nerve lesions.

Adolescent↗
PubMed2001

Muscle ergoreceptor overactivity reflects deterioration in clinical status and cardiorespiratory reflex control in chronic heart failure.

BACKGROUND: In chronic heart failure (CHF), overactivation of ergoreceptors (afferents sensitive to the metabolic effects of muscular work) may be a link between peripheral changes, sympathetic overactivation, and increased hemodynamic and ventilatory responses to exercise. The relationship between ergoreceptors, autonomic changes, and the progression of the syndrome has not yet been studied. METHODS AND RESULTS: Thirty-eight stable CHF patients (age, 57+/-1 years; ejection fraction, 26+/-2%) were compared with 12 age-matched normal control subjects. The ergoreflex contribution to the ventilatory and hemodynamic responses to exercise, together with peripheral and central chemoreceptor sensitivity, arterial baroreflex sensitivity, plasma norepinephrine, epinephrine, and heart rate variability, were measured. Enhanced ergoreflex effects on ventilation (78+/-2% versus 50+/-8%), peripheral chemosensitivity (0.6+/-0.4 versus 0.2+/-0.1 L/min per percent SaO(2)), and central chemosensitivity (2.9+/-0.2 versus 2.0+/-0.2 L. min(-1). mm Hg(-1)) and an impaired baroreflex function (4.1+/-0.6 versus 9.1+/-5.6 ms/mm Hg) were confirmed in CHF compared with control subjects (P<0.01 in all comparisons). Ergoreceptor overactivity was associated with a worse symptomatic state (NYHA class, P<0.05), lower exercise tolerance (peak VO(2), P<0.05), and pronounced exercise hyperventilation (VE/VCO(2), P<0.01). It was also a strong predictor of increased central chemosensitivity (independently of clinical parameters), baroreflex impairment, and sympathetic activation (plasma catecholamines and heart rate variability indexes; all P<0.05). In multivariate analysis, among all reflexes studied, the ventilatory component of the ergoreflex was the only independent predictor of peak VO(2) and VE/VCO(2). CONCLUSIONS: In CHF, overactivation of the ergoreflex is associated with abnormal cardiorespiratory reflex control, independently of clinical severity. Among impaired reflexes, overactivation of the ergoreflex is an important determinant of exercise hyperventilation and reduced exercise tolerance.

Autonomic Nervous System↗
PubMed1991

H-reflex modulation during walking in spastic paretic subjects.

Hoffman (H) reflexes were elicited from the soleus muscle during treadmill walking in 21 spastic paretic patients. The soleus and tibialis anterior muscles were reciprocally activated during walking in most patients, much like that observed in healthy individuals. The pattern of H-reflex modulation varied considerably between patients, from being relatively normal in some patients to a complete absence of modulation in others. The most common pattern observed was a lack of H-reflex modulation through the stance phase and slight depression of the reflex in the swing phase, considerably less modulation than that of normal subjects under comparable walking conditions. The high reflex amplitudes during periods of the step cycle such as early stance seems to be related to the stretch-induced large electromyogram bursts in the soleus in some subjects. The abnormally active reflexes appear to contribute to the clonus encountered during walking in these patients. In three patients who were able to walk for extended periods, the effect of stimulus intensity was examined. Two of these patients showed a greater degree of reflex modulation at lower stimulus intensities, suggesting that the lack of modulation observed at higher stimulus intensities is a result of saturation of the reflex loop. In six other patients, however, no reflex modulation could be demonstrated even at very low stimulus intensities.

Adult↗
PubMed1988

Ipsilateral acoustic-reflex adaptation testing for detection of facial-nerve pathology: three case studies.

Abnormal acoustic-reflex adaptation monitored in the same ear for both contralaterally and ipsilaterally presented tonal activators is reported in three cases. One case had Bell's palsy, whereas the other two cases had no clinically observable evidence of seventh-nerve involvement. These cases show that the existence of abnormal acoustic-reflex adaptation in the absence of Bell's palsy does not necessarily implicate the presence of eighth-nerve pathology.

Acoustic Impedance Tests↗
PubMedDate not supplied

Outcome of facial nerve palsy in 24 children.

Of 24 children with facial palsy, 6 (25%) had recurrent attacks. Complete recovery occurred in 21 (88%). Electrophysiological tests including direct stimulation of the facial nerve and blink reflex were performed in 12 serially to compare the prognostic value. Only direct response had prognostic significance in predicting the outcome. A normal direct response predicts a better prognosis (P = 0.002) whereas abnormal blink reflex can be associated with complete or incomplete recovery.

Acute Disease↗
PubMed2001

Intrinsic and reflex stiffness in normal and spastic, spinal cord injured subjects.

Mechanical changes underlying spastic hypertonia were explored using a parallel cascade system identification technique to evaluate the relative contributions of intrinsic and reflex mechanisms to dynamic ankle stiffness in healthy subjects (controls) and spastic, spinal cord injured (SCI) patients. We examined the modulation of the gain and dynamics of these components with ankle angle for both passive and active conditions. Four main findings emerged. First, intrinsic and reflex stiffness dynamics were qualitatively similar in SCI patients and controls. Intrinsic stiffness dynamics were well modeled by a linear second-order model relating intrinsic torque to joint position, while reflex stiffness dynamics were accurately described by a linear, third-order system relating half-wave rectified velocity to reflex torque. Differences between the two groups were evident in the values of four parameters, the elastic and viscous parameters for intrinsic stiffness and the gain and first-order cut-off frequency for reflex stiffness. Second, reflex stiffness was substantially increased in SCI patients, where it generated as much as 40% of the total torque variance, compared with controls, where reflex contributions never exceeded 7%. Third, differences between SCI patients and controls depended strongly on joint position, becoming larger as the ankle was dorsiflexed. At full plantarflexion, there was no difference between SCI and control subjects; in the mid-range, reflex stiffness was abnormally high in SCI patients; at full dorsiflexion, both reflex and intrinsic stiffness were larger than normal. Fourth, differences between SCI and control subjects were smaller during the active than the passive condition, because intrinsic stiffness increased more in controls than SCI subjects; nevertheless, reflex gain remained abnormally high in SCI patients. These results elucidate the nature and origins of the mechanical abnormalities associated with hypertonia and provide a better understanding of its functional and clinical implications.

Adult↗
PubMed1995

Oculomotor function in amyotrophic lateral sclerosis: evidence for frontal impairment.

Saccadic eye movements, fixation, and smooth pursuit were recorded in 17 subjects with amyotrophic lateral sclerosis (ALS) and 11 age-matched controls using a magnetic scleral search coil. Reflexive, remembered and antisaccades, and smooth pursuit at four target velocities were studied. Subjects with ALS showed significantly elevated error rates (distractibility) and latency in the antisaccade and remembered saccade paradigms but no abnormality of reflexive saccades. The frequency of small saccades that intruded on steady fixation (square-wave jerks) was also increased in ALS subjects. Peak velocity gain of smooth pursuit and performance on the Wisconsin Card Sort Test did not differ significantly between the two groups. These findings are consistent with prefrontal dysfunction in ALS and provide an independent source of support for the thesis that the pathology of this condition invades frontal cortex.

Adult↗
PubMed2001

A case of inability to belch.

A 22-year-old man was unable to belch. He could sense intraesophageal gas, but had no chest pain. An upper gastrointestinal X-ray series and endoscopic examination showed no abnormalities. Esophageal manometry showed normal relaxation of both the upper and lower esophageal sphincters with primary peristalsis during deglutition. However, bolus injection of air into the middle esophagus failed to initiate the belch reflex.

Adult↗