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PubMed2006

Operant conditioning of H-reflex can correct a locomotor abnormality after spinal cord injury in rats.

This study asked whether operant conditioning of the H-reflex can modify locomotion in spinal cord-injured rats. Midthoracic transection of the right lateral column of the spinal cord produced a persistent asymmetry in the muscle activity underlying treadmill locomotion. The rats were then either exposed or not exposed to an H-reflex up-conditioning protocol that greatly increased right soleus motoneuron response to primary afferent input, and locomotion was reevaluated. H-reflex up-conditioning increased the right soleus burst and corrected the locomotor asymmetry. In contrast, the locomotor asymmetry persisted in the control rats. These results suggest that appropriately selected reflex conditioning protocols might improve function in people with partial spinal cord injuries. Such protocols might be especially useful when significant regeneration becomes possible and precise methods for reeducating the regenerated spinal cord neurons and synapses are needed for restoring effective function.

Animals↗
PubMed1977

[Somatosensory evoked potentials and Hoffmann reflex in acute spinal cord lesions; physiopathological and prognostic aspects].

Twenty-four patients with recent and acute spinal cord lesions were examined. The somatosensory cerebral evoked potential (SEP) following stimulation of the peroneus communis nerve tested spinal conduction, whereas the H reflex showed spinal excitability belowe the lesion. After complete spinal cord section, the SEP was always abolished and the H reflex was absent in most cases tested in the first 24 hours. Into other patients, the recruitment curve and the recovery cycle of the H reflex displayed some abnormalities which progressively disappeared. With partial lesions, SEP could occasionally be altered. Some abnormalities of the H reflex recovery cycle, of the same type as those seen in the late stage of complete sections, were also observed. These data give nre information on the physiopathology of spinal shock; they lead to the distinction of several evolutionary stages after acute spinal lesions and also have prognostic disgnificance.

Adolescent↗
PubMed1986

A brain syndrome associated with delayed neuropsychiatric sequelae following acute carbon monoxide intoxication.

A summary of clinical data is presented on 34 men and 52 women patients with brain syndrome associated with delayed neuropsychiatric sequelae following acute carbon monoxide intoxication. Their ages ranged from 34 to 82 years, with peak incidence in the sixth and seventh decade. Possible etiological factors were age, duration of unconsciousness on acute intoxication, and previous physical illness. The onset was relatively sudden after the apparent clear period which ranged from 2 to 40 days (mean 22.5 days). The most frequent symptoms were apathy, dull facial expressions, dementia, such as amnesia and disorientation, hypokinesia, mutism, irritable distractibility, urinary and/or fecal incontinence, gait disturbance and abnormal neurological signs and reflexes. EEG was abnormal in 33 of the 57 cases (58%). Of 27 patients who were given a computed tomographic brain scan, 15 patients were abnormal. The prognosis was relatively good in the follow-up study of 56 patients. Only age was related to a better prognosis.

Acute Disease↗
PubMed1991

Clinical application of saccade-reflex testing in man.

Computer-aided measurements of saccade-reflex reaction times, velocities, and accuracies have become important tools in the detection of central nervous system pathology. Because of improved knowledge of the reflex pathways in man, saccade testing can assist in differentiating between brain stem, cerebellar, or cerebral disorders and point toward unilateral lesions. Saccade-reflex testing is also useful in determining disability and measuring over time the course of central nervous system disorders. Further work, correlating lesions observed by high-resolution imaging techniques with abnormalities in reflexes, continues to improve the understanding of saccade mechanisms in man. Specific cases are used to show the effects of anatomic lesions on changes in saccade reflexes. The results from 100 consecutive patients evaluated for dizziness are provided in order to illustrate the prevalence of saccade abnormalities and the relationship between abnormalities in vestibular and slow and fast eye-movement reflexes. Patients complaining of disequilibrium and visual disturbances frequently have abnormalities in the saccade system, abnormalities which are often overlooked in present clinical testing of the dizzy patient.

Adolescent↗
PubMed1999

ERP P300 and brain magnetic resonance imaging in patients with vibroacoustic disease.

INTRODUCTION: Subjects occupationally exposed to large pressure amplitude (> or = 90 dB SPL) and low frequency (< or = 500 Hz) (LPALF) noise for long term periods (>10 yr) can develop vibroacoustic disease (VAD). One of the earliest complaints of VAD patients deals with memory and attention disturbances. On the other hand, in over 50% of these patients, magnetic resonance imaging (MRI) of the CNS revealed cortical atrophy and dilation of the perivascular spaces, and small hyperintense lesions in T2 of the cerebral white matter, basal ganglia, and brainstem. The purpose of this study is to investigate whether there is any relationship between these morphological changes and the event-related potentials (ERP) P300 parameters. METHODS: Sixty aeronautical workers with more than 10 yr of LPALF noise exposure were studied using brain MRI and ERP P300. A careful neurological examination had been previously performed on all of them. RESULTS: The neurological examination revealed abnormalities in 80%, the most common finding being the archaic palmo-mental reflex. Some 37 subjects had hyperintense foci in T2 of the subcortical and periventricular white matter, the basal ganglia and the brainstem. Comparing the ERP P300 amplitude and latency values, morphology and topography, obtained in these 37 subjects with the data from the 23 who did not have any morphological changes in CNS, we found a strong correlation between the brain MRI lesions and the neurophysiological changes (p < 0.01). CONCLUSIONS: These results are important for understanding the pathophysiology of the cognitive impairment found in VAD patients.

Adult↗
PubMed2002

Incidence of cardiac autonomic neuropathy and its correlation with retinopathy, micro-albuminuria and glycated haemoglobin in non-insulin dependent diabetes mellitus.

Forty non-insulin dependent diabetes mellitus (NIDDM patients were subjected to bedside evaluation of cardiovascular autonomic reflexes. Autonomic neuropathy was detected in 23 patients (57.5%); orthostatic hypotension in 6 (15%), abnormal blood pressure response to sustained handgrip in 8 (20%), abnormal Valsalva ratio in 10 (25%), abnormal heart rate response to deep breathing in 12 (30%) and abnormal heart rate response to standing in 11 patients (27.5%). Incidence of parasympathetic neuropathy was 57.5% in comparison to 20% sympathetic neuropathy One abnormal cardiac reflex was seen in 6 (15%), 2 in 13 (32.5%) and 3 or more in 4 patients (10%). Raised glycated haemoglobin was seen in 17 patients,retinopathy in 3 and micro-albuminuria in 11 patients with autonomic dysfunction and in 13, 0 and 3 patients respectively in NIDDM patients without autonomic neuropathy. Positive correlation of cardiac autonomic neuropathy was seen with retinopathy and micro-albuminuria.

Adult↗
PubMed1981

A comparison of stapedial reflex fatigue with repetitive stimulation and single-fiber EMG in myasthenia gravis.

The pattern of stapedial reflex fatigue in response to pulsed acoustic stimulation was measured and compared to results of repetitive nerve stimulation and single-fiber electromyography (EMG) in 89 patients with myasthenia gravis. Studies were also made on 22 patients with other neuromuscular disorders and 40 control subjects with no evidence of neuromuscular impairment. Stapedial reflex fatigue exceeded normal control values in 84% of the patients with myasthenia gravis. Repetitive stimulation and single-fiber EMG measurements were abnormal in 56% and 91% of this same population, respectively. Stapedial reflex abnormalities were most prevalent in patients with mild forms of myasthenia (predominantly ocular or oropharyngeal weakness). Of 22 nonmyasthenic patients with neuromuscular disease tested, 6 had abnormal stapedial reflex fatigue according to our normal values, indicating that this form of testing also detects other diseases of the motor unit. The measurement of stapedial reflex fatigue is painless, is easy to perform, and requires minimal patient cooperation. Due to the relatively high occurrence of abnormal stapedial reflex fatigue in patients with myasthenia gravis, this procedure appears to have considerable potential value in screening and monitoring patients for the presence of defects in neuromuscular transmission.

Acoustic Stimulation↗
PubMed1997

Spinal manipulation results in immediate H-reflex changes in patients with unilateral disc herniation.

The aim of this clinical investigation was to determine whether the abnormal H-reflex complex present in patients with S1 nerve root compression due to lumbosacral disc herniation is improved by single-session lumbar manipulation. Twenty-four patients with unilateral disc herniation at the L5-S1 level underwent spinal H-reflex electro-physiological evaluation. This was carried out before and after single-session lumbar manipulation in the side-lying position. Eligibility criteria for inclusion in the study were: predominant sciatica, no motor or sphincteric involvement, unilateral disc herniation at the L5-S1 level on CT or MR imaging, age between 20 and 50 years. H-reflex responses were recorded bilaterally from the gastrosoleous muscle following stimulation of tibial sensory fibers in the popliteal fossa. H-reflex amplitude in millivolts (HR-A) and H-reflex latency in milliseconds (HR-L) were measured from the spinal reflex response. Pre- and post-manipulation measurements were compared between the affected side and the healthy side. Statistical evaluation was performed by the Wilcoxon matched-pairs test (SPSS). Thirteen patients displayed abnormal H-reflex parameters prior to lumbar manipulation, indicating an S1 nerve root lesion. The mean amplitude was found to be significantly lower on the side of disc herniation than on the normal, healthy side (P = 0.0037). Following manipulation, the abnormal HR-A increased significantly on the affected side while the normal HR-A on the healthy side remained unchanged (P = 0.0045). There was a significant difference between latencies on the affected side and those on the healthy side (P = 0.003). Following manipulation there was a trend toward decreased HR-L. However, this trend did not reach statistical significance (P = 0.3877). Eight patients displayed no H-reflex abnormalities before or after manipulation. Their respective HR-A and HR-L values did not change significantly following manipulation. Three additional patients were excluded due to technical difficulties in achieving manipulation or measuring spinal reflex. These observations may lend physiological support for the clinical effects of manipulative therapy in patients with degenerative disc disease.

Adult↗
PubMed1995

Multiple system atrophy presenting as parkinsonism: clinical features and diagnostic criteria.

To evaluate the possibility that parkinsonian signs may be the only presenting feature of multiple system atrophy (MSA), parkinsonian patients were studied who had no atypical clinical signs and had no symptoms of autonomic dysfunction, but who reported that they had not experienced the anticipated good response to dopaminergic treatment. These stringent criteria identified 20 patients from a series of 298 consecutive parkinsonian outpatients. The following clinical pointers were analysed: (a) rate of disease progression; (b) symmetry of parkinsonian symptoms and signs; (c) occurrence of resting tremor during the first three years from onset. In addition, all patients underwent (d) acute and chronic challenge with dopaminergic drugs; (e) cardiovascular reflex autonomic function tests; (f) high field MRI. Rapid progression of disease was seen in 45% of patients, onset was symmetric in 25%, tremor was absent at onset in 70%, response to dopaminergic drug challenges was inadequate in 40%, abnormal cardiovascular reflexes occurred in 50%, and some abnormal MRI finding occurred in 35% of cases. Each of these features was equally weighted by giving to each patient a 0 to 6 point score corresponding to the number of abnormal findings. Fifteen patients scoring higher than 1 were considered at risk for having MSA: five of them were classified as clinically possible (score 2), six as clinically probable (score 3-4), and four patients were classified as clinically definite multiple system atrophy (score 5). The six pointers considered were variably combined in each patient, none of them being universally abnormal in patients with high scores. The patients were followed up for a mean 2.1 (SEM 0.65) years. All but one of the 10 patients prospectively classified as probable or definite MSA developed unequivocal clinical signs of fully symptomatic MSA. A receiver operator characteristic cure was plotted for the prospective score based on follow up diagnosis. The best compromise for trade off between sensitivity and specificity was a cut off value at a score of 3. The sensitivity and specificity of the individual pointers considered to predict fully symptomatic MSA varied considerably, and no single item could predict whether patients presenting with just parkinsonian signs went on during the two year follow up period to develop fully symptomatic MSA. Instead, the number of abnormalities offered a predictive value for the clinical prognosis of these parkinsonian patients.

Adult↗
PubMed2004

Paradoxical modulation of tendon tap reflex during voluntary contraction in Parkinson's disease.

OBJECTIVE: Inadequate supraspinal modulation of spinal motor control mechanisms such as alpha-gamma coactivation is supposed to cause difficulty in maintaining proper voluntary contraction in Parkinson's disease (PD). METHODS: Subjects were 42 patients with PD and 20 normal volunteers. Soleus H-reflex and tendon tap reflex (T-reflex) were recorded. The maximal reflexes (H(max) and T(max)) at rest were recorded first. Next, the stimulus intensities were fixed to obtain a reflex size of around 25% of M(max) at rest for both H- and T-reflexes, and the reflexes were recorded at rest, during tonic plantarflexion (TPF), and at the onset of plantarflexion. RESULTS: H(max) at rest was 55% and T(max) 30% in normal subjects, while they were 36 and 31%, respectively, in PD. The size ratio of T(max) and H(max) at rest in PD was larger than normal. In PD, the size of H-reflex increased with TPF as in normal subjects, but T-reflex decreased. These changes in T-reflex were correlated with the grade of rigidity, bradykinesia, and time for 10 m gait. H-reflex had no such correlations. CONCLUSIONS: T-reflex was abnormally modulated in PD especially during tonic contraction. SIGNIFICANCE: Inappropriate supraspinal modulation of the spinal reflex pathways disturbs motor performance in PD.

Aged↗
PubMed1986

Peripheral nerve conduction studies and bulbocavernosus reflex in the investigation of impotence.

Patients with erectile dysfunction underwent sensory and motor conduction and bulbocavernosus reflex tests to determine the incidence of peripheral nerve involvement. Of a total of 111 patients, abnormal sensory conduction was found in 87 (78%), abnormal motor conduction in 56 (50%), and abnormal bulbocavernosus reflex in 40 (36%). Most of these patients had other medical problems. Objective evidence of peripheral nerve involvement helped in the management of these patients.

Adult↗
PubMed2006

Hypothetical anatomical model to describe the aberrant gag reflex observed in a clinical population of orally deprived children.

In this 'clinical conundrum', we propose a hypothetical anatomical model to explain the abnormal gag reflex that is consistently observed in a clinical population of children experiencing feeding delays. This model is based on the presence of 'transient' connections formed during the normal development of autonomic brainstem circuitry involving the nucleus tractus solitarius (NTS). We propose that, as a result of normal feeding and swallowing, the activity of these transient fibers typically diminishes shortly after birth. In children who are orally deprived during infancy, these transient connections persist and the aberrant gag reflex is maintained into childhood. The most critical feature of the proposed model is the idea that swallowing during feeding initiates the retraction of the tactile 'transient' input to NTS. In the NICU feeding clinics, it has been suggested that triggering the gag reflex in neonates by tactile stimulation of non-oral body areas and anterior portions of the mouth directly or indirectly may contribute to oral feeding delays. To the contrary, we propose an anatomical model to suggest that oral feeding delays and lack of swallowing food, when experienced by neonates, actually contribute to the development of the aberrant gag reflex observed in later developmental stages.

Deglutition↗