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PubMed1985

A variant form of metachromatic leucodystrophy in a patient suffering from another congenital degenerative neurological disease.

A woman aged 21 with a variant form of metachromatic leucodystrophy (MLD) combined with another form of leucodystrophy is described. The clinical symptoms were retinitis pigmentosa and progressive neurological deficits such as mental retardation, dystonia, pyramidal tract involvement and peripheral neuropathy. The biochemical findings were marked deficiency of arylsulfatase-A and cerebroside-sulfatase in cultured fibroblasts and excretion of sulfatides in the urine. Sulfatide-loading of cultured fibroblasts showed almost normal uptake and degradation of sulfatides. The patient's sister suffers from a clinically similar neurological disease, but normal activity of arylsulfatase-A was found in her leucocytes. A severe oral-facial dystonia in the patient was successfully controlled by l-dopa.

Adult↗
PubMed1991

Evoked potential abnormalities in progressive spastic paraparesis associated to HTLV-1.

The electrophysiological features of progressive spastic paraparesis (PSP) associated with HTLV-1 in Chile, a non-tropical country, are presented. Twenty-two of 45 PSP subjects were positive for HTLV-1 antibodies. Trimodal evoked potentials were all normal in only 2 of these cases (9.1%). Somatosensory evoked potentials (SSEPs) were abnormal in 19 patients (86.3%) with a mean amplitude of 1.31 uV SD 0.92. Visual evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs) were normal in all patients except four. Peripheral nerve conduction was normal in all but one who showed discrete slowness of the motor conduction velocity in the peroneal nerves. EMG was normal in 15 cases in whom it was performed. SSEP's were abnormal in 2 (8.7%) of 23 HTLV-1 negative cases with a mean amplitude of 2.4 uV SD 1.5, which is statistically different with respect to the positive cases (p less than 0.001). These results support an involvement of the spinal cord not restricted to the pyramidal tracts but also including subclinical damage of the posterior columns in PSP associated to HTLV-1.

Adult↗
PubMed1992

Benign monomelic amyotrophy of lower limb: report of three cases.

Three patients with wasting confined to a single lower limb are reported. The characteristic features were: sporadic occurrence, insidious onset with slow progression and in 2 cases arrested course for at least 4 years, wasting out of proportion with disability, absence of sensory, pyramidal tract or bulbar signs. CK, motor and sensory conductions, and lumbar MRI were normal. Muscle CT showed selective loss of muscle tissue and fat replacement in posterior leg muscles. Quantitative electromyography and histologic findings revealed neurogenic features not only in the affected legs, but also in clinically uninvolved limbs. Monomelic amyotrophy of lower limb is a variant of spinal muscular atrophy with a benign course. However, as in the early stages of the disease there are no distinctive clinical or laboratory findings with other motor neuron diseases, the diagnosis of monomelic amyotrophy may be made only retrospectively after a prolonged observation.

Adult↗
PubMed1990

Neuronal development in vitamin B6 deficiency.

The morphological changes observed in developing brain regions associated with maternal vitamin B6 deficits are summarized in Table 4. Brain development is a complex and orderly process consisting of cell division, proliferation, migration, and maturation. In the rat, vitamin B6 deficits imposed in utero and up to 30 days postnatal interfere with this orderly process. Deficits of the vitamin imposed in utero have been associated with reduced numbers of total and normal neurons in neocortex and with increased shrunken neurons (700-1500% of controls) in this region. These changes reflect the critical role of vitamin B6 in both neurogenesis and neuron longevity in neocortex. Postnatal cellular events in the neocortex, that is, neuron differentiation and synaptogenesis, were also altered by vitamin B6 deficits; higher order dendrites were reduced on stellate neurons in Layer II and on pyramidal neurons in Layer V. Synaptic density was less in the neutrophil of neocortex and in caudate/putamen, but structural integrity of the synapse was maintained. In cerebellum, both the molecular and granular areas were reduced, the monolayer organization of Purkinje cells was disrupted, and dendritic arborization of the cells was decreased. The number of myelinated axons, as determined by electron microscopy, was decreased in the mediodorsal portion of the pyramidal tract in the medulla oblongata as well as the specific activity of myelination of the total brain. Thus the functional consequences of vitamin B6 deficits during neuronal development may be through reduced connections among neurons and decreased myelination, which alter the rate and magnitude of transmission of nerve impulses.

Animals↗
PubMed1979

The origin of the hind limb vasodilatation evoked by stimulation of the motor cortex in the cat.

In cats under Althesin anaesthesia, the hind limb area of the motor cortex has been stimulated by means of monopolar, semi-micro-electrodes with careful experimental control so as to avoid reflex effects evoked through stimulation of meningeal afferent fibres or stimulus spread to non-cortical structures. 2. Localized cortical stimulation which elicited muscle contractions in the contralateral hind limb also elicited vasodilation in the same limb: the stimulus threshold was the same for both effects, and the magnitude of the dilatation was related to the strength of contraction. 3. Reduction of the somatic motor response, caused by lesions in the medullary pyramidal tract, was accompanied by a parallel reduction of the vascular response. 4. Prevention of the motor response by gallamine or by spinal cord section at L4--L5 (which leaves the sympathetic outflow to the hind limbs intact) led to abolition of the vascular response. During recovery from gallamine, contraction and vasodilatation returned in parallel. 5. The muscle vasodilatation was insensitive to atropine or guanethidine. 6. It is concluded that the hind limb vasodilatation observed on stimulation of the motor cortex is simply a post-contraction hyperaemia, and that it is independent of the sympathic nervous system. Previous conclusions of a sympathetically mediated vasodilatation probably resulted from inadequate control of the stimulus or a failure to recognize weak muscle contractions.

Animals↗
PubMed1981

Variety of functional organization within the monkey motor cortex.

1. Single-unit recordings have been made from 606 neurones in the arm region of area 4 in five conscious monkeys. Their activity during a stereotyped motor task and their responses to passive natural stimulation of the limb have been investigated.2. 88% of area 4 neurones responsive to natural stimulation received their afferent input from a restricted region of the contralateral arm.3. The activity and afferent input to cell groups have been determined by comparing the properties of neurones located within 500 mum of each other and recorded in one and the same micro-electrode penetration. 115 such cell groups containing 344 neurones were investigated.4. 75/115 cell groups (65%) contained neurones with input from the same arm zone (shoulder, elbow, wrist or hand) and with a similar pattern of task-related activity. Cell groups containing neurones with identical afferent inputs never showed contrasting behaviour during movement.5. 40/115 cell groups (35%) contained neurones receiving inputs from more than one arm zone. Twenty-five cell groups (22%) had two contiguous zones (e.g. wrist and hand) represented and ten groups had input from two discontinuous zones (e.g. elbow and hand). These differences in input within a cell group were usually reflected in contrasting behaviour of its constituent neurones during movement.6. Pyramidal tract neurones (PTNs) lying immediately adjacent to one another usually received similar inputs and exhibited matching behaviour. PTNs lying further apart in the same penetration often showed different activity and responded to different stimuli.7. The topographic distribution of afferent input to area 4 revealed multiple representation of input from a single zone combined with considerable intermingling of input from all four zones. Neurones with shoulder and elbow inputs surrounded those with wrist inputs which in turn lay scattered around a central zone. This central zone only contained neurones with hand inputs, although neurones with hand inputs were found outside this central zone.8. The significance of this complex organization is discussed in terms of motor cortex input and output.

Afferent Pathways↗
PubMed1984

Locomotor-related neuronal discharges in cat motor cortex compared with peripheral receptive fields and evoked movements.

Discharge patterns of motor cortical neurones in cats walking steadily on a moving belt have been compared with other functional characteristics of the neurones. In forelimb motor cortex rhythmic discharges occurred in cells with peripheral receptive fields in all parts of the contralateral forelimb and also in cells with no discernible receptive field. Cells discharging at similar times during the step cycle often had very different receptive fields and cells with similar receptive fields (including neighbouring cells) could discharge at similar or at quite different times. In cells with a cutaneous receptive field including the forefoot the discharges during locomotion remained rhythmic (and their phasing relative to the step cycle was unchanged) when the response to mechanical stimulation in the receptive field was temporarily much reduced or abolished by local anaesthesia of the skin. The proportion of neurones showing accelerated firing during different parts of the step cycle fluctuated more for antidromically identified pyramidal tract neurones (p.t.n.s) than for non-p.t.n.s and was highest during the second half of stance in the contralateral forelimb and lowest during swing. When the neurones were subdivided according to the movement evoked by threshold electrical stimulation through the micro-electrode, p.t.n.s and non-p.t.n.s recorded by electrodes evoking elbow flexion showed a wide variety of discharge patterns. For p.t.n.s the discharge rate reached an average of 69 impulses/s during late stance and declined to an average of 26 impulses/s during swing.

Action Potentials↗
PubMed1993

The role of the motor cortex in the control of accuracy of locomotor movements in the cat.

1. The impulse activity of single neurones in the motor cortex (MC) was recorded extracellularly, using movable varnish-insulated tungsten microelectrodes, in six adult, freely moving cats. Neuronal activity was recorded while the cats walked on a flat floor, as they stepped over a series of barriers, and as they walked on the flat rungs of a horizontal ladder. The mean discharge rate (mR) and the depth of frequency modulation (dM) in each cell were estimated over 10-100 steps. 2. The activity of ninety-eight MC cells (Including thirteen pyramidal tract neurones (PTNs)) was recorded during stepping over barriers 25 cm apart. The mR in 66% and the dM in 61% of these cells changed by more than 20% during locomotion with barriers compared to locomotion on the flat (an increase was more often the case). 3. The activity of nine cells was recorded during stepping over barriers 12 cm apart, and the activity of twenty-seven cells (including five PTNs) during walking with barriers only 6 cm apart. The mR in 67% and in 59% of the cells, respectively, and the dM in 56% and in 67% of the cells, respectively, were greater in these locomotor tasks than during locomotion on the flat. 4. The activity of twenty cells was recorded during walking and compared in experiments with different distances between barriers. The mR in 50% and the dM in 75% of the neurones progressively increased when the distance between successive barriers was diminished. 5. The discharge rates of thirteen cells were compared in two different locomotor tasks: (i) when the cat stepped over barriers requiring hyperflexion of the limbs and (ii) when it walked on the flat with loads attached to the distal forelimbs causing a hyperactivity of flexor muscles. The activity of nine cells was different during stepping over the barriers compared to locomotion with loadings on the forelimbs. 6. The activity of 108 cells (twenty-four PTNs) was recorded during walking along a horizontal ladder with flat rungs. The mR of 61% and the dM of 72% of cells changed by more than 20% during locomotion on the ladder compared with that on the flat (most often they increased). 7. The position of the peak rate relative to the step cycle did not differ in the majority of cells (in 78-91% depending on the task) during locomotion on the flat, with the barriers or on the ladder.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

The role of the motor cortex in the control of vigour of locomotor movements in the cat.

1. The impulse activity of single neurones in the motor cortex (MC) was recorded extracellularly using movable varnish-insulated tungsten microelectrodes in four adult freely moving cats. The cats walked inside the experimental box with various loadings in the swing or stance phases of the step cycle. The mean discharge rate (mR) and the depth of frequency modulation (dM) in each neurone were estimated over 10-100 steps. 2. The activity of thirty-one cells (including eighteen pyramidal tract neurones (PTNs)) was recorded during uphill walking on a 10 deg inclined floor. The mR in 68%, and the dM in 77% of neurones changed by less than 20% during uphill locomotion compared to walking on a level surface. 3. The activity of the same neurones was also recorded during downhill walking, also on a 10 deg inclined plane. The mR in 69% and the dM in 78% of neurones changed by less than 20% during downhill locomotion compared with walking on a level surface. 4. The activity of twenty-three (the left hemisphere) cells (sixteen PTNs) during walking with the floor swaying to the right (R) and to the left (L) was compared to activity during locomotion on a stable surface. The mR in 83% and the dM in 83% of cells in R-steps, and in 82 and 77% of cells, respectively, in L-steps changed by less than 20%. 5. The activity of thirty-seven cells was studied during locomotion at various speeds. The mR in 68% and the dM in 38% of cells changed by less than 20% during fast and slow locomotion compared to middle-speed locomotion. The dM in 46% of neurones increased with the transfer from slow to fast walking. 6. The activity of thirty-one MC cells was recorded during locomotion with loads of 85 g attached to the distal part of each elbow. The mR in 52% and the dM in 48% of neurones changed by more than 20%. 7. The activity of twenty-eight cells (six PTNs) was studied in steps when an animal turned. The swing of the limb contralateral to the recorded MC was shorter (condition 1) in turning steps in one direction, and was longer (condition 2) in turning steps in the opposite direction. The mR in 50% and the dM in 50% of cells in condition 1 and in 52% and 59%, respectively, of cells in condition 2 changed by more than 20%.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed2006

Hypoxia-sensing properties of the newborn rat ventral medullary surface in vitro.

The ventral medullary surface (VMS) is a region known to exert a respiratory stimulant effect during hypercapnia. Several studies have suggested its involvement in the central inhibition of respiratory rhythm caused by hypoxia. We studied brainstem-spinal cord preparations isolated from newborn rats transiently superfused with a very low O(2) medium, causing reversible respiratory depression, to characterize the participation of the VMS in hypoxic respiratory adaptation. In the presence of 0.8 mM Ca(2+), very low O(2) medium induced an increase in c-fos expression throughout the VMS. The reduction of synaptic transmission and blockade of the respiratory drive by 0.2 mM Ca(2+)-1.6 mM Mg(2+) abolished c-fos expression in the medial VMS (at the lateral edge of the pyramidal tract) but not in the perifacial retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) VMS, suggesting the existence of perifacial RTN/pFRG hypoxia-sensing neurons. In the presence of Ca(2+) (0.8 mM), lesioning experiments suggested a physiological difference in perifacial RTN/pFRG VMS between the lateral VMS (beneath the ventrolateral part of the facial nucleus) and the middle VMS (beneath the ventromedial part of the facial nucleus), at least in newborn rats. The lateral VMS lesion, corresponding principally to the most rostral part of the pFRG, produced hypoxia-induced stimulation, whereas the middle VMS lesion, corresponding to the main part of the RTN, abolished hypoxic excitation. This may involve relay via the medial VMS, which is thought to be the parapyramidal group.

Animals↗
PubMed2004

Familial leptomeningeal amyloidosis with a transthyretin variant Asp18Gly representing repeated subarachnoid haemorrhages with superficial siderosis.

OBJECTIVES: To report the clinical features of two Japanese brothers with familial leptomeningeal amyloidosis, showing a causative gene abnormality of a transthyretin (TTR) variant Asp18Gly, previously reported only in a Hungarian family. METHODS: The authors reported on a 42 year old man (patient 1) and his 45 year old brother (patient 2), both suffering from subarachnoid haemorrhage (SAH) without and with hydrocephalus, respectively. DNA sequences of the TTR gene were determined in both patients and the patients' clinical features described. A surgical biopsy of the leptomeninges was performed on patient 1. RESULTS: DNA sequence analyses demonstrated the glycine-for-aspartate substitution at position 18 of the TTR variant. Both patients revealed pyramidal tract signs and cerebellar ataxia. Audiometric studies showed bilateral, mild sensorineural hearing loss in the patients whose cerebrospinal fluid (CSF) protein levels increased. T1 weighted MRI after contrast administration showed diffuse leptomeningeal enhancement along the Sylvian fissures and over the surface of the brainstem, cerebellum, and spinal cord. Gradient echo T2* weighted MRI showed superficial siderosis mainly in the cerebellum. A biopsy of the leptomeninges was obtained from the spinal cord of patient 1. While performing the biopsy, the authors observed the varicose, elongating, and fragile veins on the dorsal surface of the spinal cord. Immunohistochemical study revealed marked deposits of TTR derived amyloid on his leptomeninges. CONCLUSIONS: This is the second report of familial leptomeningeal amyloidosis with an Asp18Gly TTR gene mutation, clinically causing only CNS symptoms. Repeated SAH from fragile veins on the dorsal surface of the spinal cord seemed to induce superficial siderosis of the CNS. So far, there have been two reliable hallmarks leading to the diagnosis of leptomeningeal amyloidosis: diffuse leptomeningeal enhancement on contrast MRI and greatly increased CSF protein content. This study has contributed a third hallmark: the presence of superficial siderosis is useful in diagnosing leptomeningeal amyloidosis.

Adult↗
PubMed2005

Mirtazapine increases cortical excitability in healthy controls and epilepsy patients with major depression.

BACKGROUND: Epilepsy is often complicated by depression requiring antidepressant treatment. Such treatment might be proconvulsive. OBJECTIVE: To examine the effects of the noradrenergic and specific serotonergic antidepressant mirtazapine on motor cortex excitability in epilepsy patients with depression and in healthy controls, using transcranial magnetic stimulation (TMS). METHODS: Seven clinically depressed epilepsy patients treated with anticonvulsant drugs and six healthy volunteers were studied. Before intake of mirtazapine and 24 hours afterwards (and also three weeks afterwards in the patients), the active and resting motor threshold (AMT, RMT), the size of the motor evoked potential (MEP), the cortical silent period (SP), and intracortical inhibition/facilitation and intracortical facilitatory I wave interactions were determined using single and paired pulse TMS. RESULTS: At baseline, AMT and RMT were higher (p = 0.049 and p = 0.04, respectively) and the ratio SP duration/MEP area greater in patients (p = 0.041). In patients but not in healthy subjects AMT was lower 24 hours after intake of mirtazapine (p = 0.028). Mirtazapine had no significant effect on the MEP size, duration of the SP, or the ratio of SP duration to MEP size in patients. The duration of the SP was longer (p = 0.037) but the ratio of SP duration to MEP size remained similar in healthy subjects after mirtazapine. There were no significant differences in paired pulse measures between the two groups either at baseline or after mirtazapine. CONCLUSIONS: Mirtazapine increased neuronal excitability of pyramidal tract axons in an activated state in both healthy controls and epilepsy patients with major depression.

Adult↗
PubMed1973

Hyperpathia in the central cervical cord syndrome.

Seven patients are described with hyperextension or flexion injury to the cervical cord. They illustrate the symptoms and signs previously associated with damage to the centre of the cord, in that weakness is greater in the upper limbs than the lower. We do not believe that the relative sparing of the legs can be accounted for on the basis that corticospinal fibres passing to the lumbar anterior horn cells lie laterally in the pyramidal tract, as has previously been suggested by Schneider, Cherry, and Pantek (1954) as there is no evidence that there is such lamination in man. Severe pain in the shoulders and arms was a major symptom in six of the patients, even in those with relatively minor injuries. The nature of this pain was initially often not recognized.

Adult↗
PubMed1974

Neurological manifestations of organophosphorous insecticide poisoning.

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.

Facial Paralysis↗
PubMed1977

Some observations on SMON from Bombay.

Nine patients in whom subacute myelo-opticoneuropathy (SMON) was diagnosed with varying degrees of confidence are discussed. The cases were discovered after a retrospective examination of our records for the period 1967-71, and a prospective search from March 1972 to date. Subacute myelopathy with predominant dysaesthesiae and greater involvement of the pyramidal tracts was seen more often than fully developed SMON. Subacute myelopathy was seen in six instances, opticomyelopathy in two and myeloneuropathy only once. Clioquinol could not be excluded as an aetiological agent. The difference in the reported prevalence of SMON between Japan and India is noted, and factors which may account for this difference are discussed. Problems related to the diagnosis of SMON outside Japan, and particularly in India, are stressed.

Adult↗
PubMed1978

Excitability relationships between lower limb myotatic arcs in spasticity.

The excitability of a lower limb myotatic reflex arc is modulated by the antecedent activation of another myotatic arc in the same limb; the changes can be represented by heteronymous excitability curves. This work compares heteronymous excitability curves in spastic and normal subjects. Eighteen patients who showed clear signs of pyramidal tract lesions at a chronic stage were studied. Three myotatic arcs of the lower limb (soleus, quadriceps, and short biceps) were activated either by mechanical percussion (T Sol-T Quad-TSBi) or by electrical stimulation of the afferent nerve (H Sol-H Quad). They were used as conditioning and test responses in six different combinations, and the results compared to those obtained previously in normal volunteers. In spastic patients, heteronymous excitability curves are more obviously modified than homonymous ones. The changes are most prominent in the thigh muscles and less marked when the soleus reflex is conditioned by activation of quadriceps and biceps femoris myotatic reflex arcs.

Adult↗
PubMed1978

Abnormalities of Bell's phenomenon in amyotrophic lateral sclerosis: a clinical and electrophysiological evaluation.

A clinical and electromyographic study of oculomotor function was carried out in a series of 24 patients with amyotrophic lateral sclerosis (ALS). In 15 cases an alteration of Bell's phenomenon was found. In addition, three patients showed some impairment of conjugate ocular motility in the form of upward gaze paly. All cases had preserved oculocephalic reflexes in the vertical and horizontal planes. On clinical and electromyographic grounds, three degrees of altered Bell's phenomenon are suggested: attenuated (short and unsustained upward displacement of the eyeballs after forced closure of the eyelids), abolished (no upward displacement), and inverted (downward instead of upward displacement of the eyes). These oculomotor alterations were not directly related to the type of ALS at onset of the illness, nor with its duration. However they were correlated with the relative degree of the clinical bilateral pyramidal tract signs at the supraspinal level. The common involvement of the corticogeniculate tract in ALS could explain the unexpectedly high incidence of alteration of Bell's phenomenon found in this disease, but is is non-specific and similar lesions from different causes may also produce it.

Adult↗