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PubMed2002

Babinski sign.

Despite all of the medical advances, Babinski sign has proved reliable in precise localization of central nervous system dysfunction. It is well accepted that Babinski sign is indicative of dysfunction of fibers within the pyramidal tract. Joseph François Félix Babinski first described the clinical significance of the reflex in 1896. He showed that the extensor plantar response was indicative of pyramidal dysfunction and that it was absent in hysteria. He also illustrated that it was present in infancy and transiently appeared in epilepsy and strychnine poisoning. Babinski also pointed to the existence of "formes frustes" of his reflex and recognized its occasional absence in patients with other clinical signs of pyramidal lesions. The sign emerges when the dysfunction of the pyramidal tract involves the fibers that project on motoneurons of foot muscles and is mediated by extensor hallucis longus. Babinski sign may not be present acutely after transverse lesions of the spinal cord or acute brain lesions because of temporary inexcitability of spinal motoneurons.

Journal Article↗

PubMed2005

Time course of wallerian degeneration after ischaemic stroke revealed by diffusion tensor imaging.

Wallerian degeneration (WD) after ischaemic stroke is a well known phenomenon following a stereotypical time course. Whereas conventional magnetic resonance imaging fails to detect signal intensity changes until four weeks after stroke, diffusion tensor imaging (DTI) reveals changes related to WD only after days. DTI was used to monitor the time course of Wallerian degeneration of the pyramidal tract from the early subacute to the late chronic stage of ischaemic stroke in two patients. A progressive decrease of fractional anisotropy was found along the pyramidal tract in the cerebral peduncle below the primary lesion resulting from progressive changes in the principal diffusivities, as well as a slight increase in the orientationally averaged diffusivity in the chronic phase. These signal changes reflect the progressive disintegration of fibre structures resulting from WD.

Anisotropy↗

PubMed1991

Lower extremity motor evoked potentials in multiple sclerosis.

Transcranial magnetic stimulation was performed on 25 patients with definite multiple sclerosis. Motor evoked potentials were recorded from the anterior tibial muscle. Central motor conduction time was calculated using the equation (F + M-1)/2 by stimulation of the common peroneal nerve. Motor evoked potentials were capable of detecting subclinical pyramidal tract lesions in multiple sclerosis. In patients with multiple sclerosis, the incidence of abnormality of motor and somatosensory evoked potentials was similar. Central motor conduction time was correlated with overall and pyramidal tract subscores on the Kurtzke Disability Status Scale and the Scripps Neurological Rating Scale. Central motor conduction time abnormalities correlated best with the presence of a Babinski's sign but also correlated significantly with weakness and hyperreflexia.

Adult↗

PubMed1987

X-linked recessive inheritance of ataxia and adult-onset dementia: clinical features and preliminary linkage analysis.

Three generations of a family exhibit a unique syndrome of X-linked ataxia, pyramidal tract signs, and adult-onset dementia. Initial signs, manifested by 2 to 3 years of age, are delayed walking and tremor. During their teens, the patients develop mild but progressive ataxia and pyramidal tract signs. Memory problems in the third decade initiate a progressive dementia, leading to death in the sixth decade. Laboratory investigations failed to disclose a biochemical basis for the syndrome. Preliminary molecular linkage studies have been conducted, and although the specific position of the responsible gene on the X chromosome has not yet been determined, the q26-qter region and much of the p arm are unlikely sites for this gene. The linkage studies are continuing.

Adolescent↗

PubMed2005

Cerebellum lesions and finger use.

We tested monkeys, patients, and normal control human subjects in a task that requires skilled use of the fingers. Animals and patients with lesions of the cerebellum, particularly of the cerebellar hemispheres, were severely impaired in retrieving raisins from small holes (monkeys) or shifting beads from place to place through a series of such holes, using the index finger alone or in apposition (humans). As they descend through the pontine nuclei, pyramidal tract fibres give off a collateral to pontine cells. The axons of pontine cells, in turn, project to the cerebellar cortex, where they terminate as mossy fibres. We suggest that the corollary discharge from pyramidal tract fibres to the cerebellum via the pontine nuclei is required for skilled, co-coordinated, simultaneous or sequential movements.

Adolescent↗

PubMed1990

Spinal and muscle motor evoked potentials following magnetic stimulation in cats.

Motor evoked potentials (MEP) from transcranial magnetic stimulation were successfully recorded from the spinal cord and gastrocnemius muscle in cats. The spinal MEP consisted of four negative peaks, N1 through N4, and subsequent small, multiphasic waves. The conduction velocity calculated from N1 corresponded to that of the nonpyramidal cerebellar evoked potential. After ablation of the pyramidal tract at various levels, N1 through N3 persisted, whereas N4 disappeared. The muscle MEP showed the same latency as that of MEP obtained by direct cortical electrical stimulation and disappeared after similar ablation. These findings suggest that the first three peaks of the spinal MEP are responses of the nonpyramidal cerebellospinal pathways and that the fourth peak of the spinal MEP and the muscle MEP are pyramidal tract responses. Spinal and muscle MEP from magnetic stimulation may be valuable in the qualitative evaluation of the function of the pyramidal and nonpyramidal pathways.

Animals↗

PubMed2006

Broadening the phenotype of childhood-onset dopa-responsive dystonia.

BACKGROUND: Dopa-responsive dystonia (DRD) may cause early-onset dystonia, with extrapyramidal or pyramidal tract dysfunction. OBJECTIVE: To broaden the phenotype of DRD. SETTING: Tertiary referral university hospital. PATIENTS: We describe 4 female siblings with genetically confirmed DRD, 3 of whom presented with "unsteadiness" and 1 with scoliosis. All had dystonia and pyramidal tract signs, 3 had additional extrapyramidal features (resting tremor, bradykinesia, or rigidity), and at least 2 had definite signs of cerebellar dysfunction. MAIN OUTCOME MEASURES: The subjective response to treatment with 62.5 mg of a combination product of levodopa and carbidopa 3 times daily was assessed at both 6- and 12-month follow-up visits with the 7-item Patient's Global Impression of Change Scale as very much improved, much improved, a little improved, no different, a little worse, much worse, or very much worse. RESULTS: All patients showed a good response to levodopa therapy 41 to 49 years after symptom onset. CONCLUSION: Cerebellar signs may be observed in patients with DRD and may improve in response to levodopa.

Dystonic Disorders↗

PubMedDate not supplied

On pure motor hemiplegia (Fisher's syndrome).

The authors described three cases of so-called "lacunar strokes" with pure motor hemiplegia. Clinical diagnosis in all three cases was middle cerebral artery thrombosis. In cases 1 and 2 small post-malacic lacunes were found in the basal part of the pons. In case 3 the lesion was located in the pyramidal tract within the pons and medulla. In all cases advanced arteriosclerotic changes were observed. "Lacunar stroke" can result from a lesion of both the pons and the medulla. The clinical syndrome may be engendered also by selective lesion of the pyramidal tract.

Aged↗

PubMed2004

Characterization of central nervous system structures by magnetic resonance diffusion anisotropy.

Diffusion-weighted magnetic resonance imaging (MRI) provides information about tissue water diffusion. Diffusion anisotropy, which can be measured with diffusion tensor MRI, is a quantitative measure of the directional dependence of the diffusion restriction that is introduced by biological structures such as nerve fibers. Diffusion tensor MRI data was obtained in the brain, brain stem, and cervical spinal cord. For each region, scans were performed in four normal volunteers. Fractional anisotropy (FA), an index of diffusion anisotropy, was measured within regions of interest located in the corpus callosum, capsula interna, thalamus, caudate nucleus, putamen, brain cortex, pyramidal tract of the medulla, accessory olivary nucleus, dorsal olivary nucleus, inferior olivary nucleus, spinal white and gray matter. The highest FA value was measured in the corpus callosum (81 +/- 3%). The values of the other areas decreased in the following order: pyramidal tract in the medulla (72 +/- 1%), spinal white matter (65 +/- 4%), capsula interna (62 +/- 3%), accessory olivary nucleus (36 +/- 2%), spinal gray matter (35 +/- 5%), dorsal olivary nucleus in the medulla (29 +/- 2%), thalamus (28 +/- 2%), inferior olivary nucleus (15 +/- 2%), putamen (13 +/- 2%), caudate nucleus (13 +/- 2%), and brain cortex (9 +/- 1%). Our results indicate that the underlying fiber architecture, fiber density, and uniformity of nerve fiber direction affect anisotropy values of the various structures. Characterization of various central nervous system structures with diffusion anisotropy is possible and may be useful to monitor degenerative diseases in the central nervous system.

Anisotropy↗

PubMed1998

[Neuroimaging of motor disturbances].

High-field MRI has given us a great impact in the clinical diagnosis of various motor disturbances, because the structural abnormalities of the pyramidal tract, basal ganglia and cerebellum are easily observed with this technique. In case of lower motor neuron disease without clinical upper motor neuron sign, proton density-weighted image of the internal capsule and cerebral peduncle is useful for detecting the latent pyramidal tract degeneration. Differential diagnosis of parkinsonism is one of the most successful examples of the clinical use of high-field MRI. Postero-lateral putaminal T2-hypointensity which has been reported to be diagnostic for multiple system atrophy (MSA) might be seen in the aged normal subjects, whereas the proton density weighted image of the normals revealed no abnormal change in signal intensity. In MSA, not only T2-weighted but also proton density image show marked hypointensity in posterior part of putamen. Proton density image of pons, moreover, reveals "four of dice sign" representing the degeneration of the pontine transverse fibers. Another pathological condition which could be differentiated from PD with MRI is PSP. Characteristic "humming-bird sign" of the mid brain on the mid-sagittal section is thought to represent the atrophy of the rostro-dorsal mid-brain tegmentum, where the vertical gaze centers are located. MRI is also useful for differentiating the pathological processes of cerebellar atrophies. Cortical cerebellar atrophy with loss of Purkinje cells shows the disappearance of T2-hypointensity of dentate nucleus, while cerebellipetal atrophy like olivopontocerebellar atrophy causes T2-hyperintensity of cerebellar white matter making dentate hypointensity more conspicuous. Degeneration of the dentate neucleus is revealed by the T2-hyperintensity of dentate contour associated with atrophy of superior cerebellar peduncle at the level of rostral pons.

Humans↗

PubMed1989

Effect of postnatal starvation on the 5 alpha-reductase activity of the brain and of the isolated myelin membranes.

The 5 alpha-reductase, the enzyme which converts testosterone into its major "active" metabolite (dihydrotestosterone, DHT), has been found to be present in high concentration in brain structures particularly rich of myelin (white matter structures), as well as in myelin membranes. Previous ontogenetic observations seem to indicate that, during the process of myelinogenesis, the enzyme might be synthesized in the oligodendrocytes, and subsequently incorporated into the myelin membranes. It is well established that postnatal malnutrition produces a decreased formation of myelin, when starvation is performed from birth until to the 2nd or 3rd week of life; on the contrary food deprivation does not produce any significant effect on myelin accumulation when performed after the 14th day of life. The present experiments have been performed in the rat in order to study the effects of postnatal undernutrition (from birth to the 19th day of life: long malnutrition; and from the 14th to the 19th day of life: short malnutrition) on the 5 alpha-reductase activity present in the following brain structures: cerebral cortex, hypothalamus, corpus callosum, pyramidal tract, as well as in isolated myelin membranes. Undernourished animals have been killed at 20 days of age. Normally nourished animals served as controls. Long undernutrition induced a statistically significant decrease of the formation of DHT in the corpus callosum and in the pyramidal tract vs controls. On the contrary, the nutritional deficiency did not decrease the 5 alpha-reductase activity in the cerebral cortex and in the hypothalamus.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed1989

Central motor conduction time in patients with HTLV-1 associated myelopathy.

Transcranial electrical stimulation of the motor cortex was performed in 7 patients with human T-lymphotropic virus type-I associated myelopathy (HAM) and 15 normal subjects. The mean value of central motor conduction time (CCT) for the thenar and hypothenar muscles in patients with HAM was not different from that in normal subjects. In contrast, mean CCT value for the tibialis anterior and gastrocnemius muscles in patients with HAM was 8.54-10.34 ms longer than the value in normal subjects. These findings indicate that the lesion of pyramidal tract involvement in patients with HAM is mainly localized in the descending corticomotoneuron pathways at the thoracic spinal cord level. This technique could be used in a clinical study without untoward side effects, and may be valuable in detecting clinically silent lesions involving the pyramidal tract.

Adult↗

PubMed1988

[Characteristics of the neuronal activation of the pontine nuclei proper in the cat in cortico- and cerebellofugal impulse flow].

Antidromic activation of the pontine nuclei neurons evoked by stimulation of brachium pontis, brachium conjunctivum (in rare cases), cerebellar central nuclei, pyramidal tract and sensorimotor cerebral cortex was studied in narcotized cats using the intracellular recording technique. The projection to the cerebellar lateral nucleus was shown to be the most pronounced among pontine nuclear projections. Monosynaptic excitation of the pontine nuclei neurons during stimulation of the pyramidal tract, cerebellar central nuclei and brachium conjunctivum was revealed. Peculiarities and significance of the connections revealed for the functioning of cortico-ponto-cerebellar system are discussed.

Animals↗

PubMed1995

[Two siblings of familial amyotrophic lateral sclerosis with multisystemic degeneration characterized by mild involvement of the middle root zone of the posterior column, Clarke's nuclei and spinocerebellar tract].

The aim of this study is to clarify the clinicopathological characteristics of the multisystem degeneration seen in two male siblings with familial amyotrophic lateral sclerosis (FALS). A similar neurological disorder affected their elder sister and paternal uncle, but not their parents. The older brother (case 1) developed muscular weakness at 50 years of age and the younger brother (case 2), at 42 years of age. The duration of illness was 19 months in case 1 and 31 months in case 2. The clinical picture was the common (suspended) form in case 1 and the pseudopolyneuritic form in case 2. Pyramidal tract sign was obscure in both cases and cerebellar sign, sensory disturbance, sphincter disturbance and oculomotor palsy were not observed in either case. Neuropathological examination revealed similar findings in the two cases: 1) marked loss of lower motor neurons in the spinal anterior horn and motor nuclei of the lower brain stem in both cases, with neuronal loss of Onuf's nuclei in case 2; 2) very mild involvement in Clarke's nuclei, the dorsal and ventral spinocerebellar tracts and the middle root zone of the posterior column; 3) relatively well preserved Betz cells in the upper motor cortex with the appearance of a few macrophages, and mild changes in the pyramidal tract of the spinal cord; and 4) mild degenerative changes in the pallidoluysian system and the dentatorubral system. The most characteristic pathological findings common to both cases were the extremely mild involvement of the middle root zone of the posterior column, Clarke's nuclei and spinocerebellar tracts. The pattern of lower motor neuron system degeneration paralleled the development of clinical features. Genetic studies demonstrated no mutations in exons 1, 2 and 4 of Cu/Zn-binding superoxide dismutase gene. We emphasized the existence of mild involvement of middle root zone of posterior column, Clarke's nuclei and spinocerebellar tract in FALS with multisystemic degeneration.

Adult↗

PubMed2004

Functional anatomy of motor recovery after early brain damage.

Functional magnetic resonance imaging and transcranial magnetic stimulation were used to examine a 34 year-old right-handed patient, who, at the age of 6 years, had experienced sudden right hemiplegia, seizures, and stupor during a bout of measles encephalitis, followed by incomplete distal right motor recovery. Morphological MRI showed massive unilateral enlargement of the left ventricle, associated with extreme thinning of the white and gray matter,with partial preservation of the pyramidal tract. Functional MRI and transcranial magnetic stimulation revealed reorganization of the motor cortices, and integrity of the corticospinal pathway, respectively. Our findings indicate that complete hand motor recovery may require functional connections between the motor cortical areas and cortical-subcortical structures, in addition to the retained integrity of the primary sensorimotor area and pyramidal tract.

Adult↗

PubMed2005

Assessing behavioural function following a pyramidotomy lesion of the corticospinal tract in adult mice.

We have developed a pyramidotomy model in mice to lesion the corticospinal tract at the level of the brainstem pyramidal tract, and evaluated the resultant impairments in motor function in a series of behavioural tests. Adult C57BL/6 mice received a unilateral pyramidotomy and a control group of mice underwent sham surgery. We studied the effects of this lesion on forepaw function using five behavioural paradigms, some of which have been widely used in rat studies but have not been fully explored in mice. The tests used were: a rearing test, which assesses forepaw use for weight support during spontaneous vertical exploration of a cylinder; a grid walking test, which assesses the ability to accurately place the forepaws during exploration of an elevated grid; a tape-removal test, which measures both sensory and motor function of the forepaw; a CatWalk automated gait analysis, which provides a number of quantitative measures including stride length and stride width during locomotion; and a staircase reaching task, which assesses skilled independent forepaw use. All tests revealed lesion effects on forepaw function with the tape removal, grid walking, rearing and CatWalk tests demonstrating robust effects throughout the testing period. The development of a pyramidotomy lesion model in mice, together with behavioural tests which can reliably measure functional impairments, will provide a valuable tool for assessing therapeutic strategies to promote regeneration and plasticity.

Analysis of Variance↗

PubMed1990

The Microtubular Pattern Changes at the Spinal Cord-Root Junction and Reverts at the Root-Peripheral Nerve Junction in Sensory and Motor Fibres of the Rat.

In the rat, we studied the microtubular content of central nervous system (CNS) axons (pyramidal tract, dorsal funiculus, and intracord domain of motor axons), of radicular axons (ventral and dorsal roots), and of peripheral axons (sural and lateral gastrocnemius nerves). The microtubular density had an inverse relationship with the size of the axon. Within the CNS, values ranged from over 120 microtubules/microm2 for axons smaller than 0.1 microm2 of the pyramidal tract and dorsal funiculus to 24 for 3-microm motor axons (area, 7 microm2) in their spinal cord domain. Peripheral nerve and CNS axons of the same size had comparable microtubular densities. In contrast, the microtubular density of dorsal and ventral root axons was one half that of CNS or peripheral nerve axons of equal calibre. Considered along the axon, the microtubular density of motor and sensory fibres is high in the CNS domain, low in the root, and high again in the peripheral nerve domain. These observations are inconsistent with the notion that the cytoskeleton moves coherently away from the perikaryon. We conclude that the axonal microtubular content accords with the calibre of the fibre and with the anatomical region where it courses. We propose that axonal microtubules are regulated by local cues.

Journal Article↗

PubMed1985

[Characteristics of monosynaptic connections between neurons of the callosal system and specific thalamic nuclei].

In the sensorimotor cortex of awake rabbits monosynaptic afferent and efferent connections of callosal neurons (CN) with ipsilateral specific thalamic nuclei (ventral posterolateral, ventral posteromedial, ventral lateral and anteroventral nuclei) were analyzed by electrophysiological method and compared with those of target-units of callosal fibres (TU). It was demonstrated that CN and TU differed in their monosynaptic inputs from the thalamus and in their axons projecting to these structures and/or being a part of the pyramidal tract. These differences were the following: a greater portion of TU had the descending projections (54%) as compared with CN (14%); 22% of TU responded by monosynaptic action potentials to the stimulation of specific thalamic nuclei, while CN never manifested such responses. TU could project to the thalamus through the main axon stem as well as through the collaterals of the pyramidal tract axons. It is supposed that the discovered differences evidence for the much greater convergence of the thalamic relay neuron effect on TU, thus revealing the mechanism underlying the differences both in receptive field properties and in the background and evoked activity of CN and neurons synaptically excited in response to the transcallosal stimulation.

Animals↗