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Biomedical subjects

L M Luxon

Publications and source records attributed to L M Luxon.

At least 19 recordsLinked to original sources
PubMed1995

Dizziness following head injury: a neuro-otological study.

Dizziness is a frequent and debilitating complications of head injury and accounts for increasing numbers of medico-legal claims. A detailed neuro-otological study was carried out from the records of 100 patients with post-traumatic dizziness to explore the neuro-otological basis of their symptoms: 50 patients presenting for medico-legal purposes (group I) and 50 presenting for management of their vestibular symptoms (group II). The two groups showed a similar sex distribution, a similar range of causes of head injury and similar severity of head injury (72 minor, 24 moderate and 4 severe). Of the 100, 88 showed at least one audio-vestibular abnormality on testing. Vertigo of the benign positional paroxysmal type was the commonest vestibular diagnosis in both groups (61/100), and only 8 patients showed central vestibular abnormalities. Fifty-three patients had audiometric abnormalities attributable to the head injury, the commonest of which was a high-tone sensorineural hearing loss. There was no significant difference in the incidence of any of the abnormalities in the medico-legal group (group I) when compared with the symptom management group (group II). The results provide strong evidence for an organic basis to recurring dizziness after head injury, whether or not a claim for compensation is pending, and emphasize the need for specialist neuro-otological investigation if abnormalities are to be identified and managed correctly.

Adult↗
PubMed1995

Relationship between balance system function and agoraphobic avoidance.

There is a striking similarity between the situations avoided by people with agoraphobia and the environments which provoke disorientation in people with organic balance disorders. This study investigated the possibility that agoraphobia might be linked to balance system dysfunction by comparing the results of balance system tests in 36 people with symptoms of panic and agoraphobia and 20 normal controls. A traditional battery of audiovestibular tests was supplemented with moving platform posturography, which assesses the postural instability induced by disorienting perceptual conditions. Subjects also completed questionnaire measures of somatic symptoms of dizziness and anxiety, agoraphobic cognitions, avoidance behaviour and state anxiety. Over 60% of the Ss with symptoms of panic and agoraphobia were destabilised by the disorienting perceptual conditions, compared with just 10% of the normal controls. Postural instability was strongly related to reported agoraphobic avoidance (r = 0.63, P < 0.01), even after controlling for symptoms, anxiety and agoraphobic cognitions. In our discussion we consider alternative interpretations of these findings, future directions for research, and implications for therapy.

Adult↗
PubMed1995

Mechanisms of hearing loss in acoustic neuroma: an otoacoustic emission study.

Evoked otoacoustic emissions (EOAE) are active mechanical responses from the cochlea which provide information about the integrity of the preneural cochlear receptor mechanisms. It may be hypothesised, therefore, that if a hearing impairment is neural in origin, normal EOAEs may be obtained from the cochlea, which, although dissociated, is functioning normally. This study examined the status of the cochlea with EOAE in patients with cochlear (Meniere's disease) and neural (surgically proven acoustic neuroma) disease. In patients with presumed cochlear lesions, no emissions were present with mean hearing worse than 40 dB across a frequency range of 0.5 to 4 kHz. Similarly, an EOAE was not present in any of the 26 acoustic neuroma patients studied when the average (0.5 to 4 kHz) hearing was greater than 40 dB. We conclude that dissociation of the cochlea in patients with acoustic neuroma appears to be rare and, in fact, cochlear involvement occurs in most cases. Possible mechanisms responsible for the effect on the cochlea in this group include degenerative changes due to chronic partial obstruction of the blood supply by the tumour, biochemical alterations in the inner ear fluids, loss of efferent control of active mechanical tuning, and hair cell degeneration secondary to neuronal loss in the eighth nerve.

Acoustic Stimulation↗
PubMed1992

Diabetes mellitus associated with a pathogenic point mutation in mitochondrial DNA.

Family studies of diabetes mellitus (DM) show that patients are more likely to have affected mothers than affected fathers. Since the inheritance of mitochondrial (mtDNA), unlike nuclear DNA, is exclusively maternal, could it be that defect(s) in mtDNA account for some cases of DM? Such defects have been associated with rare neurological syndromes, in some of which DM has been an accompanying feature. We have looked for glucose intolerance and for a previously known point mutation of mtDNA in a family, some of whose members have a multisystem disorder with DM but not neurological involvement. DNA samples were obtained from fourteen family members. The point mutation (affecting position 3243 in the tRNA leucine mitochondrial gene) was found in all three diabetic patients and post mortem tissues in the proband; it was also found in seven offspring of female patients. It was not found in the two children of the male proband. The contribution of this mutation to DM in general is not known but clinicians ought to be aware of the possibility, especially in families with multisystem disease and maternal transmission.

Adult↗
PubMed1992

Coordination of eye and head movements during smooth pursuit in patients with vestibular failure.

During pursuit of smoothly moving targets with combined eye and head movements in normal subjects, accurate gaze control depends on successful interaction of the vestibular and head movement signals with the ocular pursuit mechanisms. To investigate compensation for loss of the vestibulo-ocular reflex during head-free pursuit in labyrinthine-deficient patients, pursuit performance was assessed and compared under head-fixed and head-free conditions in five patients with isolated bilateral loss of vestibular function. Target motion consisted of predictable and unpredictable pseudo-random waveforms containing the sum of three or four sinusoids. Comparison of slow-phase gaze velocity gains under head-free and head-fixed conditions revealed no significant differences during pursuit of any of the three pseudo-random waveforms. The finding of significant compensatory eye movement during active head movements in darkness in labyrinthine-deficient patients, which were comparable in character and gain to the vestibular eye movement elicited in normal subjects, probably explains the similarity of the head-fixed and head-free responses. In two additional patients with cerebellar degeneration and vestibular failure, no compensatory eye movement response was observed, implying that the cerebellum is necessary for the generation of such responses in labyrinthine-deficient patients.

Adult↗
PubMed1992

Psychiatric morbidity in patients with peripheral vestibular disorder: a clinical and neuro-otological study.

This study reports the psychiatric morbidity in 54 patients with objective evidence of peripheral vestibular disorder seen three to five years after their original referral. A third of the patients were free from vestibular symptoms at follow up and a further third had experienced some improvement. Two thirds of the patients had experienced psychiatric symptoms during this period, although only 50% were rated above the cut off point for significant psychiatric disturbance when interviewed. Panic disorder with or without agoraphobia and major depression were the commonest psychiatric diagnoses. Patients with classical "labyrinthine" symptoms had a more severe canal paresis than the rest, but the degree of the abnormalities in the neuro-otological tests was unrelated to outcome or to psychiatric morbidity. On the other hand, there was a significant correlation between the presence of vestibular symptoms and psychiatric morbidity, which in turn correlated with measures of anxiety, perceived stress and previous psychiatric illness.

Adolescent↗
PubMed1991

The neck-eye reflex in patients with reduced vestibular and optokinetic function.

It is accepted that the neck-eye loop (cervico-ocular reflex, COR) is enhanced following loss of vestibular function and that this helps to restore gaze stability during head movements. In this paper we address the question of which structures and/or mechanisms may participate in such plastic enhancement by investigating the COR in 2 patients with absent vestibular function and reduced smooth pursuit-optokinetic eye movements (SP-OKN). The patients had multisystem atrophy involving the vestibular system and the cerebellum. The COR (elicited by angular motion of the trunk relative to the fixed head and angular motion of the head relative to the fixed trunk) was not enhanced in these 2 patients when compared with normal subjects, in contrast to previous findings in a group of patients with absent vestibular function alone. Measurements of slow phase eye movement velocity during SP-OKN stimuli and during combined COR-OKN stimulation (head oscillation relative to the stationary trunk in the light) showed identical values in these two conditions, which indicates that the neck-eye loop did not contribute to gaze stability during head movements. The absence of plastic enhancement of the COR in these patients may be secondary to interruption of SP-OKN pathways at various possible sites and/or to involvement of the vestibulocerebellum, which is known to mediate adaptive plasticity in the vestibulo-ocular reflex.

Darkness↗
PubMed1991

Disturbances of balance in the elderly.

Dizziness and falls are a common cause of morbidity and mortality in the elderly. The pathophysiological mechanisms leading to these symptoms are legion and such patients may present in a multiplicity of medical and surgical outpatient departments. A working knowledge of the management of these disorders is therefore of value to every clinician.

Aged↗
PubMed1984

"A bit dizzy".

Dizziness is greeted by most doctors with a degree of despair and is often dismissed as a trivial complaint, despite the many causative pathologies. For the patient, it is disabling, disorientating, and, in unresolved cases, may lead to chronic invalidism. A simple approach to the problem is given.

Adult↗
PubMed1982

On the relationship of CSF pleocytosis to immunoglobulin levels as estimated by different techniques.

One might expect a positive correlation between the number of CSF lymphocytes and the relative amount of CSF IgG, especially in cases of local synthesis of IgG within the CNS. However, previous attempts at correlating the number of CSF lymphocytes with IgG levels have yielded varying results. Since it is known that the estimation of CSF IgG levels can vary according to the method of immunoglobulin determination used, we decided to perform the analyses by three separate methods: (1) the commonly used, immunoprecipitation technique of radial immunodiffusion; (2) physico-chemical separation on the basis of hydrated size/charge using alkaline electrophoresis through the molecular sieving effects of polyacrylamide gels, followed by densitometry of the gamma region of Coomassie Blue-stained proteins; (3) separation into constituent Ig heavy chains and light chains on the basis of unfolded chain lengths by molecular sieving using sodium dodecyl sulphate (SDS), followed by densitometry of heavy chains of immunoglobulins having been labelled with the fluorescent dye dansyl chloride. Our results show a correlation of white count with the latter two techniques but not the former. Possible reasons for discrepancies in the literature are discussed with regard to the peculiar physical properties of the selected CSF IgG molecules.

Cerebrospinal Fluid↗
PubMed1982

Electrophoretic separation and identification of perilymph proteins in cases of acoustic neuroma.

Previous studies of perilymph proteins have emphasised the difficulty of obtaining samples free of blood or serum proteins. The present investigation has established a method of polyacrylamide gel electrophoresis, which enables contaminated specimens to be readily identified and therefore discarded. Analysis of uncontaminated samples has confirmed the presence of an elevated perilymph protein in cases of acoustic neurinomata. Perilymph proteins have been separated and identified and although no characteristic pattern of proteins associated with acoustic neurinomata has emerged, further work should be undertaken to establish the site of origin of perilymph proteins and the pattern of abnormalities to be expected in pathological processes.

Electrophoresis, Polyacrylamide Gel↗
PubMed1981

The anatomy and pathology of the central auditory pathways.

The anatomy of the central auditory pathways from the cochlear nucleus to the auditory cortex is reviewed. The common pathologies affecting these pathways are described and the neurological, ophthalmological and vestibular symptoms and signs, which are valuable in diagnosing and siting the level of these lesions are discussed.

Auditory Cortex↗
PubMed1980

Controlled study of 24-hour ambulatory electrocardiographic monitoring in patients with transient neurological symptoms.

Sixty unselected patients with transient neurological symptoms underwent 24-hour ambulatory electrocardiographic (ECG) monitoring. Haemodynamically significant arrhythmias were observed in 32% of patients, but in only 3% of an age- and sex-matched control group. Nine patients received specific anti-arrhythmic therapy, which resulted in marked symptomatic improvement in each case. It is argued that 24-hour ECG monitoring is a valuable diagnostic tool in the investigation of transient neurological symptoms.

Adolescent↗
PubMed1980

Hearing loss in brainstem disorders.

A retrospective study of 309 unselected patients with brainstem disorders was carried out to establish the incidence and degree of hearing loss in this group as a whole and in each of three separate pathologies: multiple sclerosis, vertebro-basilar ischaemia and brainstem tumours. Pure tone audiograms were corrected for age and sex and upon analysis, thereafter, 59% and 26% of patients were found to have hearing thresholds in excess of 10dB and 30dB respectively. The hearing loss tended to be slight to moderate, 87% of those with a deficit were in the range 11--59dB, and tended to involve the higher frequencies. No characteristic audiometric configuration emerged. 75% of those with a hearing loss suffered a bilateral deficit. Considering the multiple sclerosis, vertebro-basilar insufficiency and tumour groups individually, similar findings were observed with the mildest losses occurring in multiple sclerosis and the most severe in the tumour group.

Adolescent↗
PubMed1979

Chronic subdural haematoma.

A retrospective case note survey of chronic subdural haematomata was carried out in an attempt to throw some light on the difficulties encountered in clinical diagnosis. The combination of raised intracranial pressure headache, fluctuating drowsiness and mild hemiparesis, although highly suggestive of subdural haematoma, is not always encountered, and epilepsy, aphasia, hemianopia and dense hemiplegia can all occur contrary to 'text book' descriptions. Head injury or other aetiological factors are commonly absent. The presentation may mimic tumour, dementia, cerebrovascular accident or subarachnoid haemorrhage. Non-invasive investigations may yield false negative results, although in the case of radionucleide scanning and computerized axial tomography the reliability is approaching 90 per cent. The diagnosis will, however, remain an unexpected finding at angiography in a percentage of cases.

Adolescent↗
PubMed1978

Subarachnoid hemorrhage and papilledema due to a cervical neurilemmoma. Case report.

An unusual case of a cervical neurilemmoma is presented. A 67-year-old man developed papilledema on two occasions in association with the symptoms and signs of a subarachnoid hemorrhage (SAH). He proved to have an otherwise asymptomatic cervical neurilemmoma. It is suggested that both acute and subclinical bleeding from such tumors may sometimes underlie the development of raised intracranial pressure occasionally encountered. The clinical clue to the spinal origin of the SAH was an acute onset with root pain. This case is discussed with reference to similar cases in the literature.

Aged↗