Showing papers in "Journal of Neurology, Neurosurgery, and Psychiatry in 1974"

The `subcortical dementia' of progressive supranuclear palsy

Abstract: Progressive supranuclear palsy (Steele et al.) has a characteristic pattern of dementia: (1) forgetfulness, (2) slowing of thought processes, (3) emotional or personality changes (apathy or depression with occasional outbursts of irritability), and (4) impaired ability to manipulate acquired knowledge. In many neurological disease states associated with subcortical pathology a similar pattern of dementia exists. The neurobehavioural changes of progressive supranuclear palsy thus typify a clinical pattern which may be referred to as subcortical dementia. The subcortical dementias have a striking clinical resemblance to the dementia which occurs after bifrontal lobe disease. However, the subcortical dementias can be clearly distinguished clinically from cortical dementias, other than frontal dementias. We propose as a tentative hypothesis that there may be common pathophysiological mechanisms underlying the subcortical dementias—in particular, disturbances of timing and activation. There are immediate practical implications of this hypothesis: drugs which have an effect on subcortical timing and activating mechanisms may be useful in the treatment of subcortical dementias.

The anatomical basis of prosopagnosia

Abstract: Evidence is presented that patients with prosopagnosia have right anterior inferior occipital lesions in the region of the occipital temporal junction. Many if not all cases have an additional lesion in the left hemisphere; this is often but apparently not always symmetrical with the right hemisphere lesion. This evidence is discussed in relation to the anatomical connections of these regions and the results of experiments in animals.

The working brain (an introduction to neuropsychology)

Abstract: CLINICAL NEUROSURGERY Edited by Barnes Wordall. Vol. 18. (Pp. 557; illustrated; £8 25.) Churchill Livingstone: Edinburgh. 1971. CLINICAL NEUROSURGERY Edited by G. T. Tindall. Vol. 19. (Pp. 598; illustrated; £12.) Churchill Livingstone: Edinburgh. 1972. The Congress of Neurosurgeons began in 1951 on the initiative of a group of younger neurosurgeons. In the last 20 years its membership has grown from 69 to over 1,000, but it has retained its original intentions and virility by a constitution which ensured that the office bearers and organizers were always young men. Residents in training are encouraged to join, financial concessions make it possible for them to attend meetings, and these are organized as an educational exercise, by inviting established authorities to give lectures on selected topics, chosen to provide a balanced programme. As a result Clinical Neurosurgery is a valuable volume which all neurosurgeons look forward to each year; it is in quite a different class from the usual conference tome, full of brief and unconnected papers of widely varying quality. As the title suggests Clinical Neurosurgery includes excellent clinical reviews but the two recent volumes include also a section of seminars on fundamental research-in volume 18 on coma and sleep, in volume 19 on basic mechanisms of memory. It is also the custom to invite a senior neurosurgical citizen as guest of honour and his two or three papers afford an opportunity for historical and philosophical reflections as well as an experienced perspective on clinical and experimental work. Add to this the refreshing presidential address, from one of the (angry?) young men of neurosurgery and it will be clear that these volumes really do include something of interest for every neurosurgeon, whatever his own interests or prejudices. It is a relief to be able so warmly to recommend these books, when the question posed by so many other books is whether anyone would really want to read them. The most recent volume has a more consistent theme than former ones, and that is 'head injury'. It includes papers on mechanisms as revealed by animal experiment and by a pathologist who visited the scene of the accident before examining the brains of head injury fatalities. There are chapters on engineering and socio-psychological aspects of accident prevention, as well as down to earth clinical accounts of metabolic disorders, testing for acoustic vestibular 36 damage, and aspects of prognosis. This is a significant contribution to the literature on head injury.

Cerebellar cortex, cytology and organization

Abstract: The dv/dt characteristics of a bidirectional thyristor are improved by irradiating selected portions of the device with high energy crystal lattice-damaging particles. In an exemplary embodiment, the commutating dv/dt of a triac is enhanced by the masked, selective irradiation of the boundaries between conducting portions and between the gate and the conducting portions.

Electrophysiological findings in entrapment of the median nerve at wrist and elbow

Abstract: In 117 consecutive patients with carpal tunnel syndrome and 11 patients with a compression syndrome of the median nerve at elbow, motor and sensory conduction along the median and ulnar nerves and quantitative electromyography were compared with findings in 190 normal controls of the same age. In 25% of patients with carpal tunnel syndrome in whom motor conduction and EMG were normal, the lesion was located from abnormalities in sensory conduction. The fact that conduction along the same fibres was moderately slowed from digit to palm, severely slowed across the flexor retinaculum, and normal from wrist to elbow indicates that slowing was due to demyelination at the site of compression. Fifteen per cent of the patients with carpal tunnel syndrome had clinical and electrophysiological signs of ulnar involvement. In the other patients conduction along the ulnar nerve was as in 100 normal controls. Compression at the elbow was located by electromyographical findings rather than by abnormalities in conduction.

Strümpell's familial spastic paraplegia: genetics and neuropathology.

Abstract: Uncomplicated Strumpell's disease (Strumpell's familial spastic paraplegia) with a dominant mode of inheritance is recorded in six families. The neuropathological findings in two cases from these families are given, bringing the total of similar histologically documented reports in the literature to 11. It is concluded that, although exact classification and identification of the many different hereditary neurological degenerative diseases is not yet practicable, cases conforming to the picture described by Strumpell can be separated from larger general group of familial spastic paraplegias, show a consistent clinical picture, and have a standard pathology. It is suggested that, since the lesions are confined to the longest fibre tracts in the central nervous system, the pathological process may be different from that found in the `system' degenerations.

Effect of cholinergic and anticholinergic agents on tardive dyskinesia

Abstract: Tardive dyskinesia, like several other choreiform disorders, is felt to be primarily related to dopaminergic activity within the striatum. Physostigmine has been demonstrated to improve the abnormal movements in patients with tardive dyskinesia while scopolamine tends to aggravate abnormal movements and in some cases elicits abnormal movement not previously observed. This evidence supports the hypothesis that anticholinergic therapy in patients prone to develop tardive dyskinesia may increase the incidence of this disorder by lowering the threshold for the appearance of these movements.

Hemispheric lateralization of singing after intracarotid sodium amylobarbitone

Abstract: Hemispheric lateralization of singing was investigated in patients who had transient hemiplegia after intracarotid injection of sodium amylobarbitone. It was found that after right carotid injection singing was markedly deficient, whereas speech remained relatively intact. Songs were sung in a monotone, devoid of correct pitch rendering; rhythm was much less affected. By contrast, singing was less disturbed than speech after left carotid injection. The observations indicated a double dissociation; the right hemisphere contributed more for singing, whereas the left demonstrated its usual dominance for speech. A model is proposed that encompasses audible stimuli as well as tactual or visual into a scheme of functional lateralization wherein the right hemisphere specializes in processing a complete, time-independent stimulus configuration and the left in a series of successive, time-dependent units.

Impulse conduction in multiple sclerosis: a theoretical basis for modification by temperature and pharmacological agents

Abstract: The simplest model for explaining conduction defects in multiple sclerosis (MS) and other demyelinating diseases assumes that the only abnormality present is loss of myelin. The consequences of such an assumption have been investigated by numerical solution of a well-known set of differential equations describing conduction in a model demyelinated axon. In agreement with clinical findings, we show that this model predicts that the temperature at which conduction block occurs is a steep function of the extent of demyelination, so that small temperature increases may block large numbers of conducting fibres. Decreasing calcium concentration (or increasing pH) is calculated markedly to improve the conduction velocity of conducting demyelinated fibres and will, in addition, restore conduction in blocked fibres. The effects of other pharmacological agents have also been computed. The presence of a demyelinating lesion in a nerve fibre is shown greatly to impair the ability of the fibre to conduct repetitive impulses, conduction failing at much lower frequencies than in normal fibres. These calculations provide some insight into the nature of conduction defects in demyelinated nerve, demonstrate that many clinical features of MS are the expected consequence of loss of myelin and do not require the presence of other defects for their explanation, and provide a useful approach to the search for a symptomatic therapy.

Neurological manifestations of organophosphorous insecticide poisoning

Abstract: Neurological findings are described in 200 consecutive cases of suicidal ingestion of organophosphorous insecticides. Miosis is almost universal. We found impairment of consciousness in 10%, fasciculations in 27%, convulsions in 1%, toxic delirium in 50%, and paralysis in 26%. Toxic delirium was attributed to treatment with atropine. Paralytic signs were divided into type 1 signs (present on admission) and type 2 signs (appearing later while on atropine treatment). Type 1 signs, chiefly impaired consciousness and bilateral pyramidal tract signs, respond to atropine. The most common type 2 signs are proximal limb weakness, areflexia, and cranial nerve palsies. EMG studies during type 2 paralysis show a myasthenic response in some cases. Of 36 cases with type 2 signs 15 died from respiratory paralysis after a variable period of artificial respiration. Twenty-one recovered and no residual neurological deficit has been noted. Atropine did not influence type 2 paralysis. It is claimed that type 2 signs differ significantly from those described before as `delayed neurotoxicity' and may represent an alternative mode of human toxicity with organophosphorous compounds.

Responses in human A and C fibres to repeated electrical intradermal stimulation

Abstract: The responses of A and C fibres to electrical intradermal stimulation were recorded with microelectrodes inserted percutaneously into intact human skin nerves. Unitary discharges deriving from A fibres were often encountered and sometimes even single C unit deflections were identified. When several C fibres responded to the stimulation, a compact time presentation of the filtered and dot-converted spikes improved the discrimination of individual spikes time-locked to the stimulation, so that unitary C elements could often be identified in the treated records even if the signal-to-noise ratio of the original signals was low. Increases in latency or blockings were traced in both A and C unit responses to repeated excitation, but the influence of repeated activation was more pronounced in thin nerve fibres even at low stimulation frequencies. The decreased excitability of thin nerve endings on repetitive stimulation suggests that not only central factors but also excitation failure in peripheral thin nerve fibres might be responsible for the decrease in pain perception experienced during local intense electrical intradermal stimulation at high frequencies.

Raised intracranial pressure and cerebral blood flow: 3. Venous outflow tract pressures and vascular resistances in experimental intracranial hypertension

Abstract: Pressure changes within the venous outflow tract from the brain were studied in anaesthetized baboons. Segmental vascular resistance changes were also calculated and the results correlated with the changes in cerebral blood flow, measured by the 133Xenon clearance method. Three different methods were used to raise intracranial pressure: cisterna magna infusion, a supratentorial subdural balloon, and an infratentorial subdural balloon. A close correlation was found between the cortical vein pressure and intracranial pressure with all methods of raising intracranial pressure: the overall correlation coefficient was 0·98. In the majority of animals sagittal sinus pressure showed little change through a wide range of intracranial pressure. In three of the six animals in the cisterna magna infusion group, however, sagittal sinus pressure increased to levels approaching the intracranial pressure during the later stages of intracranial hypertension. Jugular venous pressure showed little change with increasing intracranial pressure. The relationship between cerebral prefusion pressure and cerebral blood flow differed according to the method of increasing intracranial pressure. This was due to differing patterns of change in prevenous vascular resistance as venous resistance increased progressively with increasing pressure in all three groups. The present results confirm, therefore, the validity of the current definition of cerebral perfusion pressure—that is, cerebral perfusion pressure is equal to mean arterial pressure minus mean intracranial pressure—by demonstrating that intracranial pressure does represent the effective cerebral venous outflow pressure.

Regional cerebral blood flow and intraventricular pressure in acute head injuries

Abstract: Twelve patients who were comatose after head injuries were studied with serial determinations of regional cerebral blood flow, jugular PO2 tension, and intraventricular pressure. These determinations began a few hours after the injury, and were followed throughout the clinical course. Diffuse derangement of cerebral vasomotor regulation is confirmed after severe head trauma, which may contribute to deterioration and poor prognosis, and which indicates a need for therapeutic maintenance of rich oxygenation, hyperventilation with moderate hypocapnia, and steady blood pressure. Continuous recording of IVP (eventually sensitized by fluid infusion or CO2 inhalation tests) may give an early indication of the subsequent clinical state and may suggest the need to submit the patients to further investigative and therapeutic procedures.

Sensory conduction of the sural nerve in polyneuropathy.

Abstract: Using surface electrodes, sensory nerve action potentials (SAP) have been recorded in the proximal segment (mid-calf to lateral malleolus) and the distal segment (lateral malleolus to toe 5) of the sural nerve and in the median nerve in 79 control subjects. The values obtained for the distal segment of the sural nerve varied widely and in seven apparently normal subjects no SAP could be distinguished. In the proximal segment conduction velocities were over 40 m/s and there was no significant change with age, unlike the median nerve in which a highly significant slowing occurred with age. Comparison of the results of sural and median sensory conduction studies in 300 consecutive patients screened for sensory polyneuropathy confirms the value of sural nerve sensory studies as a routine screening test, and confirms the belief that the changes in polyneuropathy are usually more prominent in lower limb nerves. It is therefore suggested that studies of sural sensory conduction form the single most useful test in the diagnosis of sensory polyneuropathy.

Segmental reflex pathways in spinal shock and spinal spasticity in man

Abstract: Activity in three segmental pathways was compared in normal subjects, patients with spinal shock, and patients with established spinal spasticity. The Achilles tendon reflex (ATR) was used to estimate transmission in the Ia monosynaptic pathway. Evidence is produced implying that vibration activates motoneurones principally through a polysynaptic pathway. The tonic vibration reflex (TVR) was used to estimate transmission in this Ia polysynaptic pathway. The percentage of the motoneurone pool (M-response) that could be activated by these pathways was used as a measure of transmission. The H reflex (vibration)/H reflex (control) ratio was used as an estimate of the degree of presynaptic inhibition of the Ia monosynaptic pathway. The findings led to the following conclusions. (1) In spinal shock presynaptic inhibition is greater than normal, transmission in the Ia monosynaptic pathway is reduced, and in the Ia polysynaptic pathway virtually abolished. (2) In established spasticity presynaptic inhibition is impaired, transmission in the Ia monosynaptic pathway is increased, but transmission in the Ia polysynaptic pathway never recovers. (3) The failure of presynaptic inhibition associated with spasticity is a gradual process. A hypothesis to explain these findings is proposed.

Abnormalities of taste and smell after head trauma

Abstract: Abnormalities of taste and smell were studied in 29 patients after head trauma. These abnormalities included decreased taste acuity (hypogeusia), a distortion of taste acuity (dysgeusia), decreased smell acuity (hyposmia), and a distortion of smell acuity (dysosmia). This syndrome can occur even after minimal head trauma and can begin months after the moment of injury. The patients exhibited a significant decrease in total serum zinc concentration (patients, 77 ± 3 μg/100 ml, mean ± 1 SEM, vs controls, 99 ± 2 μg/100 ml, P>0·001) and a significant increase in total serum copper concentrations (113 ± 4 μg/100 ml vs 100 ± 2 μg/100 ml, P<0·001) compared with control subjects. Symptoms of hypogeusia, dysgeusia, and dysosmia are frequent sequelae of head injury and are important to the patients and to their care after trauma.

Aneurysms of the posterior communicating artery and oculomotor paresis

Abstract: One hundred and seventy-four patients with a posterior communicating aneurysm were seen over a 21 year period. There was a ratio of four females to one male and women were on average five years older. Fifty-nine (34%) had an oculomotor paresis. This group had up to four attacks of localized headache, large multiloculated aneurysms, and a greater time lapse from the onset of symptoms to surgery compared with those patients without oculomotor palsy. Delay in treatment allowed further attacks to occur which increased the mortality rate and decreased the chance that the eye would recover. Eighteen people who had had a palsy before craniotomy two to 18 years previously were examined. In four (22%) the paralysis had recovered completely, 14 (78%) had greatly reduced oculomotor function, and nine (50%) showed aberrant regeneration of the nerve. Nine of 62 patients, seven of whom were seen, developed a palsy after craniotomy and in five the eye had returned to normal.

Cerebral embolism and mitral stenosis: survival with and without anticoagulants

Abstract: Eighty-four patients with mitral stenosis and cerebral embolism have been followed up for 20 years. Half of the series (those treated in the early years) had no anticoagulant treatment and half were given long-term warfarin therapy. Mortality rate and causes of death have been reviewed, and comparison of survival times of treated and untreated groups by life-table analysis bears out the immediate need for anticoagulants when a diagnosis of systemic embolism is established. It is wise to continue the treatment for six months but it may be reasonable to discontinue it after one year with patients who can be assured of regular review.

Aromatic amino acids in the brain

Abstract: is being steadily carried out. Human studies on the to brain function. Thus tryptophan is, for example, thalamus and cortex are already well advanced and important in control of protein synthesis and in the ingenious gate-theory for pain has stimulated relation to formation of the biogenic amine serovaluable therapeutic studies. This volume, one of a tonin. Changes in concentration of the aromatic major new series, is a valuable record of present amino acid or its derivatives occur in sleep and ideas. As the editor rightly observes, in an active stress. It appears that the level of brain tryptophan research field it is both necessary and usual to find is a key factor in affective disorders and possibly in conflicts of ideas between different expert contribuschizophrenia, while serotonin is implicated in the tors. Doubtless many of the ideas in this book will be biochemistry of headache. Well-recognized are the superseded but it is a good summary of current views neurological effects of inborn errors of tryptophan, on the somatosensory system. phenylalanine, and tyrosine metabolism. There was, J. A. SIMPSON therefore, good reason for the holding and publication of a CIBA Foundation symposium in May 1973, CURRENT TOPICS IN NEUROPATHOLOGY Edited by at which the basic biochemistry of brain aromatic K. Jellinger. (Pp. 241; illustrated; price not amino acids was examined in depth. Each of the 20 stated.) Facultas: Vienna. 1973. articles by acknowledged experts begins with an This paper-bound volume of 241 pages contains 37 abstract and the text of about 10 pages is usually of the papers presented at the 4th Danube Symposfollowed by an edited discussion. The result is an ium on Neuropathology which was held in May excellent book in which the high scientific standard is 1973. Papers were presented by East and West matched by a clear attractive format. The book German, Polish, Rumanian, Swiss, Hungarian, begins with a review of factors controlling plasma American, and Austrian neuropathologists. Three of amino acid (especially tryptophan) concentration. the main themes of the symposium-developmental This is followed by an account of amino acid transabnormalities, inflammatory and viral diseases, and port in the brain. Their metabolism to a range of cerebral tumours and their experimental inductionbiogenic amines, as well as nutritional factors regulahave been published. There is much of interest in all ting levels of the amino acids and their derivatives, of the papers but many of them have appeared as are reviewed. formal publications in the European literature. Only Attention is particularly focused on the role of two of the papers in this volume are in English. The tryptophan and 5-hydroxytryptamine. The final part majority of the others have English summaries of the book deals with the topical question of which are either too short to convey more than the tryptophan concentration and control of brain prosimplest outlines to the non-German or have tein synthesis. Amino acid imbalance may competicompletely lost their meaning in inaccurate translatively reduce availability of amino acids for synthesis tion. As an example, the English summary of Dr or, as has been suggested, cause polysomal disaggreDudka's paper on 'Primary, circumscribed melanogation. Recent information is given on these points mas of the nervous system' seems to be far from and the use of analogues of phenylalanine and what he meant in respect of the established existence tryptophan is examined. ofmelanin containing cells in some meningiomas and A. N. DAVISON

Motor unit estimations in small muscles of the hand

Abstract: A quantal method has been employed to determine the numbers of functioning motor units in small muscles of the hand. In healthy subjects below the age of 60 years the mean number of hypothenar motor units was 380 ± 79 and the mean number of thenar units innervated by the median nerve was 340 ± 87. In older subjects there was a progressive reduction in the numbers of functioning units in both muscle groups; in some of these subjects the population of motor units in the extensor digitorum brevis was also estimated for comparison. A study was also performed on patients diagnosed as having generalized denervating diseases or with lesions of peripheral nerves and cervical roots; in every instance the number of functioning motor units was markedly reduced.

Calculation of the electromyographic jitter

Abstract: The electromyographic jitter is the variability at consecutive discharges in the time interval between two action potentials from two muscle fibres from the same motor unit. This paper deals with different methods of expressing the jitter. The method of choice seems to be Mean Consecutive Difference (MCD)[FORMULA: see text]where D(1), D(2) etc. are the individual time interval measurement data and n the number of discharges, preferably 50 or, if the jitter is not changing, 200. MCD can also be estimated from other measures of the jitter like Mean Range of Two (MR(2)) (giving the same estimated value as MCD), Mean Range of Five (MR(5)), Mean Range of Ten (MR(10)) and also from the Standard Deviation (SD). In a distribution without trends the following relations hold:MCD = 1·13×SDMCD = 0·49×MR(5)MCD = 0·37×MR(10)·The presence of slow variations and trends in most recordings makes SD not well suited for calculation because of the risk of getting too high estimates of the jitter.

Focal reflex myoclonus

Abstract: In a patient with reflex myoclonus limited to the right side of the body, stimulation of the right median nerve in the index finger or wrist elicited a very large somatosensory evoked response (SER) and a long loop C reflex which represents an electrically evoked myoclonic response. It is suggested that the pathway for the C reflex is through peripheral nerve, dorsal funiculus of spinal cord, contralateral VP nucleus of thalamus, sensorimotor cortex, corticospinal tract, and anterior horn cell. The large SER, C reflex, and myoclonic jerks are presumed to result from a release effect causing increased excitability at central synapses along this pathway. The patient presented has a large atrophic vascular lesion involving the left frontotemporoparietal region and involvement of pathways through the right superior cerebellar peduncle to account for the neural dysfunction.

The surgery of the central nervous system

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Temperature regulation in mammals and other vertebrates

Abstract: SOME PROBLEMS IN MUSCLE DISEASES Proceedings of the 2nd Conference on Myopathies at Janske Lazne. (Pp. 260; illustrated; price not stated.) Czechoslovak Medical Press: Prague. 1973. This small paper-back volume embodies the proceedings of a symposium on muscle diseases held at the spa town of Janske Laizn6 in Czechoslovakia in March 1971. It includes some 37 contributions from the 60 participants, many of whom came from Eastern Europe, but three (Emery, Hughes, and Walton) attended from Great Britain and there were also invited papers from Western Germany, Italy, France, and Switzerland. While most of the papers are brief synopses of work previously published elsewhere, and some indeed are summaries only, a number of original papers from Czechoslovakian workers are included. Many of these deal specifically with the physical and psychological management of patients with the various forms of neuromuscular disease which are treated in the Children's Medical Institute at Jafnske Lafzne. All of the papers are printed in English. The book has been printed inexpensively and the reproduction of certain of the microphotographs and electron micrographs has suffered as a result, though on the whole the illustrations are reasonably clear. Essentially the book is a short and highly selective review of some important problems in neuromuscular disease but its brevity and selectivity mean that it will have a limited appeal to readers in the U.S.A. and Western Europe to whom most of the information which it contains is readily available in extenso elsewhere.

Electromyographic and reflex study in idiopathic and symptomatic trigeminal neuralgias: latency of the jaw and blink reflexes

Abstract: Recorded jaw reflexes were studied in 51 normal subjects. In addition, the blink and jaw reflexes combined with masseteric electromyography were recorded in 17 unselected patients with facial pain. Six of these patients, including two without neurological anomalies, showed electrodiagnostic anomalies. The method proved valuable for differentiation between idiopathic and symptomatic trigeminal neuralgia.

Corpus callosum in multiple sclerosis

Abstract: A neuropathological study of 20 multiple sclerosis brains using celloidin-embedded slices was carried out to assess the extent of changes in the corpus callosum. Severe atrophy of the callosum was found in cases with marked hydrocephalus. Demyelination of the callosum varied in extent from slight involvement (with a few small plaques) to almost total myelin loss. A clinical history of mental deterioration was usual in the cases with severe callosal lesions, but no symptoms were recorded that indicated a specific disconnection syndrome. The ventricular enlargement noted in this series could not be explained either on the basis of obstruction to the flow of cerebrospinal fluid, or by the effects of shrinkage of the white matter.

Some psychological factors in Parkinsonism

Abstract: Twenty-four Parkinsonism patients were compared with `normal controls' and with another chronically disabled group, matched for age, sex distribution, and socioeconomic background, on measures of depression and some intellectual factors. A tendency to depression in the Parkinsonism sufferers was demonstrated together with an apparent specific intellectual deficit, for which a cause related to the motor disabilities of the disease is postulated.

Cerebral blood flow, internal carotid artery pressure, and the EEG as a guide to the safety of carotid ligation.

Abstract: Twenty patients with aneurysms of the internal carotid artery underwent temporary clamping, in turn, of the internal and then the common carotid artery. Cerebral blood flow, internal carotid artery pressure, and the EEG were recorded to assess the probability of cerebral ischaemia after permanent ligation. With this method of monitoring the cerebral circulation, 17 of the 20 patients had a permanent carotid ligation without neurological deficit; in the other three ligation was contraindicated. Although a correlation was observed between the reduction of cerebral blood flow and the fall in internal carotid artery pressure caused by temporary clamping (P<0·01), the scatter of data was too wide to predict cerebral blood flow from the change in carotid artery pressure. Similarly, EEG slowing was usually associated with low cerebral blood flow but exceptions occurred. Ligation was safe when, during temporary clamping, cerebral blood flow exceeded 40 ml/100 g/min, but was deemed unsafe when flow was less than 20 ml/100 g/min. In the range 20-40 ml/100 g/min, consideration of the internal carotid artery pressure permitted more patients to be safely ligated than if the decision had rested on changes in cerebral blood flow alone.

Motor nerve conduction velocity in peroneal muscular atrophy: evidence for genetic heterogeneity

Abstract: Measurements of motor nerve conduction velocity are reported in 88 subjects from 20 families in which a clinical diagnosis of peroneal muscular atrophy had been made in the index cases. The values display a bimodal distribution. The majority of cases show a substantially reduced conduction velocity, a smaller group displaying velocities within the normal range or only slightly decreased. This difference was demonstrated to have a genetic basis.