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PubMed1992

[A clinicopathological study of two respirator-aided long-survival cases of amyotrophic lateral sclerosis].

We reported two respirator-aided 10-year-survival male patients with sporadic amyotrophic lateral sclerosis (ALS). Their ages at onset were 54 and 52, clinical features common in both cases, the durations to tracheotomy 32 months and 27 months respectively, and the durations for respiratory support over 8 years in both cases. There were normal external ocular movement, normal pelvic sphincter function, normal sensory system and no bed sores throughout 10 years of illness. The brain weighted 1,295 g in case 1 and 1,430 g in case 2, being normal macroscopically. The spinal cord was slightly wasted with atrophic anterior roots. The histopathological study demonstrated the typical pattern of ALS in spite of the prolonged survival with artificial respiration. Neuronal loss and gliosis of the motor nuclei in the spinal cord and brainstem were more striking than those of the natural course. Neither hypertrophic astrocyte, central chromatolysis nor neuronophagia was observed. This finding suggested inactive condition of the degeneration. The pattern of white matter degeneration in the cord indicated some pallor of anterior and lateral columns, severe pallor of pyramidal tracts and intact posterior column and spinocerebellar tracts. The giant pyramidal cells in the precentral gyrus were lost in both cases. Pyramidal degeneration was traceable up to the cerebral peduncles in the case 2 and undetectable in that portion in the case 1. On the other hand, the extraocular muscle nuclei, the Onuf's nuclei, the dorsal motor nucleus of the vagus nerve, intermediolateral and Clarke's nuclei were relatively preserved, though no cell count was done in Clarke's nuclei and Onuf's nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1982

Convergence of sensory inputs upon projection neurons of somatosensory cortex.

Cortico-cortical neurons and pyramidal tract neurons of the cat were tested for convergent inputs from forelimb afferents. Neurons were recorded in cortical areas 1, 2, and 3a. Consideration was given to both suprathreshold and subthreshold inputs evoked by electrical stimulation of forelimb nerves. Individual cortico-cortical neurons and also pyramidal tract neurons were characterized by convergence of multiple somatosensory inputs from different regions of skin, from several muscle groups, and between group I deep afferents and low threshold cutaneous afferents. Certain patterns of afferent input varied with cytoarchitectonic area. There was, however, no difference between area 3a and areas 1-2 in the incidence of cross-modality convergence in the form of input from cutaneous and also deep nerves. Many of the inputs were subthreshold. Arguments are presented that these inputs, though subthreshold, must be considered for a role in cortical information processing. The convergent nature of the sensory inputs is discussed in relation to the proposed specificities of cortical columns. The patterns of afferent inputs reaching cortico-cortical neurons seem to be appropriate for them to have a role in the formation of sensory fields of motor cortex neurons. PT neurons of somatosensory cortex have possible roles as modifiers of ascending sensory systems, however, the convergent input which these PT neurons receive argues against a simple relationship between the modality of peripheral stimuli influencing them and the modality of the ascending tract neurons under their descending control.

Afferent Pathways↗

PubMed2003

In vivo voxel-based morphometry in multiple system atrophy of the cerebellar type.

BACKGROUND: Multiple system atrophy (MSA) is a sporadic neurodegenerative disease. According to the clinical presentation a parkinsonian type and a cerebellar type (MSA-C) are distinguished. OBJECTIVE: To study the morphological alterations of MSA-C-affected brains in vivo using voxel-based morphometric analysis of magnetic resonance images. SETTING: University hospital. PATIENTS: Fourteen patients (5 men and 9 women) with MSA-C (mean age [SD], 59.4 [7.4] years; mean [SD] disease duration, 3.7 [1.4] years) and 13 healthy control subjects (5 men and 8 women) (mean [SD] age, 55.1 [6.9] years) were studied. METHODS: T1-weighted magnetic resonance images were normalized to a common stereotaxic space and segmented into gray and white matter. Data were analyzed using statistical parametric mapping (SPM99). RESULTS: Gray matter was reduced in the brainstem and the anterior lobe of the cerebellum. Reduction of white matter was observed in the middle cerebellar peduncles, cerebellar white matter, and brainstem. The inverted comparison revealed an increase of white matter density along the pyramidal tracts. CONCLUSIONS: Voxel-based morphometry revealed a significant loss of cerebellar and brainstem tissue in MSA-C. It allowed a precise anatomical localization and a distinction between gray and white matter densities. In addition, our data point to a particular involvement of the pyramidal tract in MSA-C.

Brain Stem↗

PubMed1977

[Inseparable prognostic value of spinothalamic and corticospinal functions in severe spinal cord injuries].

In severe spinal cord trauma with initial complete paraplegia or tetraplegia, even the smallest recovery of sensibility to pain or motor function has an obvious prognostical value as it results from the study of 112 spinal injuries. For the motor aspect it is well known from experimental work and in man that even a small part of a single pyramidal tract in the spinal cord can take in charge the bilateral motricity of the limbs. It remains exceptional in severe spinal cord injury that recovery of motricity is not followed by a return of pain sens. In the lateral funiculus of the cord the sensitive and pyramidal tracts belongs to a same anastomotic vascular area between the central and peripherical circulatory streams. In physiological conditions this intermediate circulatory stream is poorly functional. But in severe spinal cord trauma with reduction of central blood flow the adjacent spinothalamic and corticospinal tracts survive in couple on the basis of the same anastomotic vascular area: from this results the prognostical unity that belongs to pain sens and motricity.

Adult↗

PubMed2003

From diffusion tractography to quantitative white matter tract measures: a reproducibility study.

The aim of this study is to propose methods for assessing the reproducibility of diffusion tractography algorithms in future clinical studies and to show their application to the tractography algorithm developed in our unit, fast marching tractography (FMT). FMT estimates anatomical connectivity between brain regions using the information provided by diffusion tensor imaging. Three major white-matter pathways were investigated in 11 normal subjects--anterior callosal fibers, optic radiations, and pyramidal tracts. FMT was used to generate maps of connectivity metric, and regions of voxels with highest connectivity metric to an anatomically defined starting point were identified for each tract under investigation. The reproducibilities of tract-"normalized" volume (NV) and fractional anisotropy (FA) measurements were assessed over such regions. The values of tract volumes are consistent with the postmortem data. Coefficients of variation (CVs) for FA and NV ranged from 1.7 to 7.1% and from 2.2 to 18.6%, respectively. CVs were lowest in the anterior callosal fibers (range: 1.7- 7.8%), followed by the optic radiations (range: 1.2-18.6%) and pyramidal tracts (range: 2.6-15.5%), suggesting that fiber organization plays a role in determining the level of FMT reproducibility. In conclusion, these findings underline the importance of assessing the reliability of diffusion tractography before investigating white matter pathology.

Adult↗

PubMed1982

Specific and non-specific multiple unit activities during pentylenetetrazol seizures in animals with mesencephalic transections.

A group of cats with brain stem transection at the mesencephalic level was studied during the administration of convulsive doses of pentylenetetrazol in regard to changes in EMG multiple unit activity (MUA), as a method to determine the course of muscular convulsions and their relation with EEG and MUA changes in the motor cortex, pyramidal tract and mesencephalic and pontine reticular formations. PTZ induced significant increase in the duration of EMG tonic convulsions, lasting 3-100 times longer than the entire tonic-clonic seizure seen in intact animals after similar doses of PTZ and not accompanied by EEG or pyramidal tract "seizures", but by an equally long-lasting increase in MUA of mesencephalic and pontine reticular formations. Comparing present results with those seen in intact, "encéphale isolé" and "pretrigeminal" preparations, it is concluded that the mesencephalon is important for both: activating tonic phase of the convulsions and the EEG changes seen in PTZ-induced seizures. It also suggests that termination of seizures is due to inhibitory influences of supramesencephalic structures.

Animals↗

PubMed1975

Cyclic AMP and cyclic GMP may mediate opposite neuronal responses in the rat cerebral cortex.

Electrophysiologically identified pyramidal tract neurons in the rat cerebral cortex were tested with norepinephrine, acetylcholine, adenosine 3',5'-monophosphate (cyclic AMP), and guanosine 3',5'-monophosphate (cyclic GMP) applied by microiontophoresis. The neurons were usually inhibited by norepinephrine and cyclic AMP, but excited by acetylcholine and cyclic GMP. These opposing responses of pyramidal tract neurons to cyclic AMP and cyclic GMP suggests that these two nucleotides could function as reciprocal intracellular second messengers for norepinephrine and acetylcholine, respectively.

Acetylcholine↗

PubMed1986

Intracortical stimulation in pyramidotomized monkeys.

In order to examine, separately, the organizations of pyramidal and extrapyramidal projections from the primary motor cortex, efforts were made to map the forelimb area of two rhesus monkeys with microstimulation before and after unilateral pyramidotomy. However, microstimulation was not effective in evoking motor responses following complete pyramidal tract section. Movements were evoked using a modified intracortical electrode with a large exposed tip and using stimulation parameters similar to those used for surface stimulation. The results from this modified intracortical stimulation generally agree with those from surface stimulation studies in that: (1) the extrapyramidal topography is similar to the normal motor cortex topography and (2) while peripheral responses can be evoked from the cortex following pyramidotomy, greater spatial and temporal summation are necessary to evoke these responses. In addition, the modified intracortical technique revealed a more widespread post-pyramidotomy digit representation than observed previously with surface stimulation. Results from an incomplete pyramidal tract lesion suggest that recovery of motor function may include plastic changes in surviving corticospinal axons.

Animals↗

PubMed1996

Fatigue in multiple sclerosis compared with chronic fatigue syndrome: A quantitative assessment.

Fatigue, a common complaint among patients with multiple sclerosis (MS), is poorly characterized. We developed a computerized method that quantitatively measures fatigue, and defined a fatigue index (FI), which is the ratio between the integral of muscle strength decay over time and maximal voluntary contraction. Thirty patients (mean age, 37.4 +/- 10.3 years) were examined - 20 patients with pyramidal tract involvement and 10 patients with involvement of other neurological systems. We evaluated 10 patients during relapse and 3 months afterwards, and compared their results with those of four patients with chronic fatigue syndrome (CFS) and 13 age-matched health subjects. The FI was significantly higher in the MS patients as compared with the CFS patients and normal controls: 34.2 +/- 6.4% versus 27.5 +/- 1.0% and 23.6 +/- 6.8%, p < 0.05. Within the MS group, the FI correlated with the presence of pyramidal signs- 43.5% compared with 33% in patients without pyramidal signs, p < 0.01. In MS patients, fatigue worsened during a relapse affecting the pyramidal tract, but not during a relapse in other systems. These results demonstrate that fatigue can be quantitatively measured in MS patients, and that pyramidal dysfunction leads to increased fatigability.

Adolescent↗

PubMed1972

Cholinergic mechanisms in the rat somatosensory cerebral cortex.

1. The responses of identified cells in the rat cerebral cortex to cholinomimetic and anticholinergic substances has been investigated.2. Acetylcholine and muscarinic agonists have an excitatory action on 80% of pyramidal tract cells. This response is found especially on cells responding to specific thalamic stimulation and the burst of spikes evoked from this site can sometimes be blocked by the iontophoresis of atropine. This strongly suggests an excitatory transmitter function for acetylcholine in a specific thalamocortical pathway.3. Experiments on non-pyramidal tract cells have detected a muscarinic depression of some cells, and a nicotinic excitation of some cells above a depth of 600 mu in the cortex.4. It is suggested that the increased release of acetylcholine from the cortex produced by atropine administration may be due to an excess of muscarinic inhibitory over excitatory synapses in the cortex.

Acetylcholine↗

PubMedDate not supplied

Fukuyama-type congenital muscular dystrophy and the Walker-Warburg syndrome.

We compared the neuropathological findings in two cases of the Walker-Warburg syndrome (WWS) with those in 6 of Fukuyama-type congenital muscular dystrophy (FCMD). Remarkable differences were noticed between the two conditions. The central nervous system (CNS) dysplasia in WWS, which involved diffuse agyria and hydrocephalus, was more severe than that in FCMD. In WWS the septum pellucidum was absent, and the corpus callosum, basal ganglia and thalami were markedly hypoplastic. The cerebellum was severely hypoplastic and the vermis was partly absent. The pyramidal tracts could not be identified. On the other hand, the general configuration of the CNS was well preserved in FCMD. The cerebral cortices exhibited diffuse or focal micropolygyria with or without a few pachygyric lesions, but the severity was variable. The cerebellum was not hypoplastic, but exhibited focal micropolygyria. The pyramidal tracts were aberrant. WWS and FCMD, however, did not show any distinct differences on microscopic analysis of the cerebral cortices. There was leptomeningeal glio-mesenchymal overgrowth, and the horizontal lamination of the nerve cells was distorted throughout by proliferating gliovascular bundles or septa. We found in this study that the CNS pathology in WWS was compatible with type II lissencephaly, and thus differed from that in FCMD. Hypoplasia of the cerebellum and a partial absence of the vermis also seemed to be predominant features of WWS, which can be used to differentiate WWS from FCMD. In this study, we concluded that FCMD and WWS are different disease entities because they differ in their clinical manifestations, including eye lesions and CNS pathology, and because no familial concomitance of FCMD and WWS has been reported.

Adolescent↗

PubMed1993

Pyramidal and corticospinal synaptic effects over reticulospinal neurones in the cat.

1. The spontaneous activity of 103 precruciate neurones (fifty-eight activated antidromically from the pyramidal tract but not from the corticospinal tract, PTNs; forty-five activated from both sites, CSNs) was used to trigger the average of the intracellularly recorded synaptic noise in 294 reticulospinal neurones (RSNs). These RSNs were recorded in the nucleus reticularis gigantocellularis of the contralateral medial bulbar reticular formation (NRGc) in chloralose-anaesthetized cats. 2. Twelve pyramidal tract neurones (six CSNs) were tested with a single RSN, twenty-six (10 CSNs) with two RSNs each, thirty (13 CSNs) with three RSNs each, and thirty-five (16 CSNs) with four RSNs each. Postsynaptic potentials were observed in the averages generated by twenty PTNs and fifteen CSNs. 3. The only synaptic effect produced by both PTNs and CSNs upon RSNs in our sample was excitatory, and in none of the tested cases (n = 15) were any changes found in the amplitude, shape, or duration of the excitatory postsynaptic potentials (EPSPs) after injection of depolarizing or hyperpolarizing currents. This suggests that the synapses are probably located at the distal dendrites. 4. Recording of the presynaptic spike allowed separation of the conduction time and synaptic delay from the total latency. According to our data there appear to be two different types of excitation of corticofugal neurones over RSNs: a monosynaptic effect produced by both PTNs and CSNs, and a disynaptic effect produced by PTNs but not by CSNs. The disynaptic EPSPs had statistically significant slower rise times and longer widths than the monosynaptic EPSPs.

Animals↗

PubMed1991

Properties of associative long-lasting potentiation induced by cellular conditioning in the motor cortex of conscious cats.

Mechanisms of long-lasting potentiation of synaptic responses induced in the thalamocortical and recurrent collateral pathways of the pyramidal tract were studied in intracellular recordings from the motor cortex of unanesthetized, chronically implanted cats. The observations provide the first description of long-lasting potentiation in the unanesthetized neocortex in vivo. Monosynaptic excitatory postsynaptic potentials of 2-5 mV in amplitude were evoked as test responses by stimulation of the pyramidal tract and thalamic ventrolateral nucleus at 0.1-0.5 Hz frequency. Pressure microinjections of drugs and ions were also performed during intracellular recordings. In the first series of experiments, test synaptic responses were paired with intracellular current injection-induced action potentials at an interstimulus interval set between 0-200 ms and 0.1-0.5 Hz frequency. Pairings (30-100 x) induced long-lasting potentiation of the test responses in 58% of cells. The increased synaptic responses typically initiated action potentials and their potentiation usually lasted over the period of recordings. Increases in amplitude of synaptic responses were not correlated with statistically significant changes in electrical membrane properties (resting potential, input resistance, time constant, spike threshold) or parameters of action potentials and their afterpotentials. The failure to induce increases in synaptic efficacy by unpaired stimuli (pseudoconditioning) demonstrated the associative property of the long-lasting potentiation. In a second series of experiments, differential cell conditioning was employed. This paradigm induced long-lasting potentiation of the explicitly paired synaptic response without noticeable modification of unpaired or pseudorandomly paired synaptic responses tested conjointly in the same neuron. These observations demonstrated the input-specificity of long-lasting potentiation. In a third series of experiments, subthreshold depolarizing current pulses were summated with synaptic responses to induce firing in the recorded neuron during pairing. Long-lasting potentiation occurred in 55% of the summated synaptic inputs. Pseudoconditioning did not induce synaptic potentiation in these cells. In a fourth series of experiments, conditioning was employed in neurons in which firing activity was suppressed by an intracellularly injected lidocaine derivative. Long-lasting potentiation was induced in 50% of the attempts when synaptic responses were paired with current-induced depolarizations greater than 30 mV. These results suggest that postsynaptic induction of long-lasting synaptic potentiation can be successful in the absence of postsynaptic sodium spikes in neurons of the motor cortex in vivo. In a fifth series of experiments, homosynaptic high-frequency tetanization (80-200 Hz for 5-15 s) was applied to the thalamocortical and recurrent pyramidal afferents.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1995

The Babinski reflex.

The plantar response is a reflex that involves not only the toes, but all muscles that shorten the leg. In the newborn the synergy is brisk, involving all flexor muscles of the leg; these include the toe 'extensors', which also shorten the leg on contraction and therefore are flexors in a physiological sense. As the nervous system matures and the pyramidal tract gains more control over spinal motoneurones the flexion synergy becomes less brisk, and the toe 'extensors' are no longer part of it. The toes then often go down instead of up, as a result of a segmental reflex involving the small foot muscles and the overlying skin, comparable to the abdominal reflexes. With lesions of the pyramidal system, structural or functional, this segmental, downward response of the toes disappears, the flexion synergy may become disinhibited and the extensor hallucis longus muscle is again recruited into the flexion reflex of the leg: the sign of Babinski. A true Babinski sign denotes dysfunction of the pyramidal tract, and should be clearly distinguished from upgoing toes that do not belong to the flexion synergy of the leg. Correct interpretation of the plantar response depends only to a minor degree on the method or site of stimulation of the foot. It is therefore most important to assess the response in the entire leg.

Humans↗

PubMed1975

Primate models of postural disorders.

Dorsal column lesions in the high cervical region of the monkey result in severe defects of movements projected into space and contactual orienting reactions of the forelimbs. The hindlimbs are less affected provided a pathway through the lateral columns, Morin's tract, remains intact. Interruption of this pathway results in a defect of hindlimb function similar to that of the forelimbs. Cerebellar ablations in monkeys result in postural and movement disorders, including hypotonia of limb extensor muscles. An important mechanism underlying the hypotonia is a depression of the responses to muscle extension of spindle primary afferents owing to a decrease of fusimotor activity. In the decerebellate animal abnormalities of limb trajectory during active movements projected into space (cerebellar "dysmetria") appear to result principally from dysfunction of systems separate from the peripheral fusimotor efferent-spindle afferent reflex arc. Precentral cortical ablation results initially in a contralateral hypotonic hemiparesis, later in a hypertonic hemiparesis. A depression of the responses of muscle spindle afferents occurs during the hypotonic phase, but during the hypertonic phase spindle function returns to normal levels. Accordingly a depression of fusimotor function appears to be important in the hypotonic phase of hemiplegia; however, there is no evidence that an enhancement of fusimotor function underlies the hypertonic phase. Bilateral section of the medullary pyramids results in an enduring hypotonic paresis. Abnormalities of contactual orienting responses of limbs are similar to those following dorsal column lesions. Responses of spindle primary afferents are depressed during the initial stages after acute pyramidotomy, then approach but do not reach normal levels. It is concluded that the dorsal columns constitute an afferent, and the pyramidal tracts an efferent, pathway important in oriented contactual reactions of the limbs. The hypotonia resulting from cerebellar lesions, precentral ablation, and pyramidal tract section stems, at least in part, from a depression of the fusimotor innervation of muscle spindle afferent activity.

Animals↗

PubMed2002

A case of paroxysmal kinesigenic dyskinesia with spastic paraparesis.

We report the first case of paroxysmal kinesigenic dyskinesia (PKD) with spastic paraparesis. A 17-year-old male began to show a dystonic posture in both his upper limbs when walking at age 12 years. Neurological examination revealed bilateral talipes cavus, spasticity in all extremities with general hyperreflexia and pathological reflexes. On starting to walk, he showed a dystonic posture in bilateral maniphalanx, wrists, elbows, and toes. Magnetic resonance imaging (MRI) revealed high T2-weighted signal intensity in bilateral pyramidal tract. Although the combination of pyramidal and the basal ganglia disorders is very rare, the present case suggests an inter-relation of the pyramidal and the basal ganglia systems.

Adolescent↗

PubMed1998

[Effect of somatosensory disturbance to outcomes of motor function in thalamic hemorrhage: evaluation with short-latency somatosensory evoked potential (SSEP)].

We investigated the effect of the somatosensory functions to the outcomes of motor functions in 28 patients with thalamic hemorrhage. The disturbance of the pyramidal tracts was assessed by the destruction of the internal capsule found in computed tomography (CT). The disturbance of the somatosensory function was analyzed by the N20 component of short-latency somatosensory evoked potentials (SSEP). The outcomes of motor function was evaluated after 3 months of ictus. Correlations between the outcomes of motor function, disturbance of the pyramidal tract, and disturbance of the somatosensory function were discussed. The result indicated that functional outcomes statistically correlated with neither disturbance of the internal capsule alone nor disturbance of N20 alone. But, there was statistically significant between functional outcomes and the combination of disturbance of the internal capsule with disturbance of N20 (p < 0.05, Wilcoxon signed-rank). There was not statistical difference in hematoma volume or consciousness. The implications of these results suggest that somatosensory function may affect the recovery of motor functions.

Aged↗

PubMed1995

Asymmetrical skin temperature in ischemic stroke.

BACKGROUND AND PURPOSE: Sympathetic dysfunction is known to manifest commonly in stroke as cardiovascular and sudomotor dysregulation, but the knowledge so far obtained concerning skin temperature and vasomotor changes in cerebrovascular diseases is contradictory. The purpose of the present study was to evaluate cutaneous temperature in ischemic stroke in a prospective follow-up study. METHODS: Skin temperature was measured at five sites on each side of the body at rest and after a heating stimulus in 44 patients with a hemispheric infarction, and in 19 patients with a brain stem infarction, in the acute phase and at 1 month and at 6 months after the infarction. RESULTS: Skin temperatures on the forearm, leg, and foot on the side contralateral to the site of infarction were significantly lower than on the ipsilateral side during the whole 6-month follow-up period. Asymmetrical temperature was associated with the presence of pyramidal tract signs in hemispheric infarction and with the presence of Wallenberg's syndrome in brain stem infarction. In hemispheric infarction, the degree of asymmetrical temperature correlated with the severity of limb paresis. CONCLUSIONS: A temperature decline in the limbs contralateral to the site of infarction seems to be a frequent, long-lasting consequence of autonomic failure in patients with stroke. The phenomenon seems to be associated with pyramidal tract signs and the presence of Wallenberg's syndrome.

Acute Disease↗