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PubMed2002

Magnetization transfer measurements of brain structures in patients with multiple system atrophy.

To determine whether magnetization transfer imaging (MTI) demonstrates abnormalities in the brain structures of patients with multiple system atrophy (MSA), we examined 12 patients with clinically probable MSA and 11 control subjects. We calculated magnetization transfer ratios (MTRs) using region of interest analysis from MTI and assessed abnormal signal changes on T2-weighted images. MTRs of the base of the pons, middle cerebellar peduncle, putamen, and white matter of the precentral gyrus were significantly lower in the MSA patients than in the controls. Abnormal signal changes on T2-weighted images were observed in the base of the pons (n = 6), middle cerebellar peduncle (n = 7), and putamen (n = 7). MTRs of regions with abnormal signals were significantly lower than those of regions without abnormal signals and those in the controls. Even the MTRs of the regions without abnormal signals were lower than those in the controls. MTRs of the pyramidal tract, including white matter of the precentral gyrus, posterior limb of the internal capsule, cerebral peduncle, and base of the pons, were significantly lower in patients with pyramidal tract sign (n = 7) than in the controls. Patients with asymmetrical parkinsonism (n = 5) showed significantly lower MTRs in the putamen contralateral to the predominant side of parkinsonian symptoms than the ipsilateral side, although asymmetry of abnormal signal changes on T2-weighted images was not evident in more than half of those patients. This study showed that MTI demonstrates abnormalities in the brains of patients with MSA that seem to reflect underlying pathological changes and that the pathological changes detected by MTI seem to give rise to clinical symptoms. This study also showed that the abnormalities are detected more sensitively and over a larger area by MTI than by conventional magnetic resonance imaging.

Aged↗

PubMed1975

[Retrograde degeneration of the pyramidal cells in the motor cortex of apes (Macaca fascicularis)].

In three adult macaques the retrograde degeneration of cell bodies in the motor cortex was investigated 6 months after unilateral pyramidal tract section. Large and small Betz cells of the fifth layer were identified microscopically and counted. The analysis of the data reveals that after pyramidotomy, (1) contrary to our expectations from the extent of the pyramidal lesions, a surprising percentage of undegenerated Betz cells remains in the contralateral motor cortex, (2) a greater percentage of small rather than large cell survives, and (3) the greatest loss of cells is in the foot region, the smallest in the face region. The results are discussed in relation to the role of pyramidal axon collaterals in the survival of cell bodies, and the distinction between pyramidal cells and pyramidal tract cells.

Animals↗

PubMed1988

Effect of long-term treatment with acetyl-L-carnitine on structural changes of ageing rat brain.

The effects of long-term treatment (11 months) with acetyl-L-carnitine (75 mg/kg daily) on the morphology of brain and optic nerve was studied in 16 senescent (22-month-old) Wistar rats (nine untreated, seven treated). Five young rats (aged 3 months) were used for comparison. Senescence was found to cause a structural disorganization of cerebral cortex, hippocampus and cerebellar cortex, and a decrease in the volume densities of the pyramidal neurons of layers 2 and 5 of the prefrontal cortex. An impaired myelination of the pyramidal tract and of the optic nerve was also observed. Besides improving the structural organization of the cerebral areas under study, treatment with acetyl-L-carnitine increased the volume densities of pyramidal neurons of the prefrontal cortex layers under observation. It must be added that myelination of the pyramidal tract and optic nerve was found to be less impaired after acetyl-L-carnitine administration.

Acetylcarnitine↗

PubMed1981

The pyramidal system of the woodchuck.

The pyramidal system of the woodchuck was examined anatomically and electrophysiologically. The pyramidal tract was found to originate entirely within the anterior half of the cerebral hemispheres and to follow a course typical of most rodents, decussating almost entirely and descending the length of the spinal cord in the ventral part of the dorsal funiculi. It decreased in size uniformly with distance along the spinal cord; most of its fibers terminated in the medial half of the dorsal horn, though they scattered widely and even appeared to terminate on motoneurons. Each tract contained 140,000 +/- 20,000 fibers, with 60-80% of the fibers being about 1 micrometer and 90% being less than 3 micrometer in diameter. Stimulation of the medullary pyramid evoked a minute antidromic potential (alpha wave) which was generally obscured by a large surface-positive response that reversed polarity deep in the cortex and that appeared to be synaptic in origin (r wave). It is proposed that the r wave results from intracortical pyramidal cell collateral activity. Though largest in the apparent region of origin of the pyramidal tract, the r wave also showed local maxima in the forepaw and hindpaw foci of somatosensory cortex. The somatosensory cortex was organized in a manner similar to other rodents, but an "association" area lacking topographical organization was found near the anterior pole of the hemispheres. In an allometric sense, the woodchuck was found to be a "normal" rodent and a "normal" mammal.

Animals↗

PubMedDate not supplied

[Probable amyotrophic lateral sclerosis. An unusual case. Review of the literature].

A case of neurological disease in a 11 year-old boy is described. The disease began early in life and had recently progressed to paraplegia with pyramidal tract dysfunction, generalized muscle atrophy and numerous fasciculations. The association of pyramidal tract and peripheral dysfunction led to the diagnosis of amyotrophic lateral sclerosis, despite some unusual features. A review of literature data concerning the juvenile and infantile types of the disease is presented, emphasizing the heterogeneity of the disease.

Amyotrophic Lateral Sclerosis↗

PubMed1966

Control of somatosensory input by cerebral cortex.

Direct stimulation of the pyramidal tract increases the size of the excitatory receptive fields of neurons in the somatosensory cortex of the cat. This effect reflects greater transmission of cutaneous information through the dorsal column nuclei as a result of the facilitation of cells in these nuclei by pyramidal tract fibers.

Animals↗

PubMed2002

Morphometrical reappraisal of motor neuron system of Pick's disease and amyotrophic lateral sclerosis with dementia.

The conventional concept of Pick's disease does not distinguish Pick's disease with Pick bodies (Pick body disease, PBD) from Pick's disease without Pick bodies [lobar atrophy without Pick bodies, LA-PB(-)]. Recently, intraneuronal ubiquitin-positive inclusions (ub-inclusions), which are thought to be a hallmark of amyotrophic lateral sclerosis with dementia (ALS-D), have been found also in LA-PB(-). We reconfirmed that ub-inclusions are consistently detected in LA-PB(-) as well as ALS-D. Subsequently, morphometric evaluation for involvement of the upper and lower motor neuron systems were performed in seven cases each of PBD, LA-PB(-), ALS-D and controls. As an indicator of upper motor neuron involvement, the total number of axons through the pyramis of the medulla oblongata was employed and for lower motor neuron involvement, the number of hypoglossal neurons per unit area was calculated. In LA-PB(-), axons of the pyramidal tract were significantly reduced in comparison to PBD and controls, while the lower motor neurons were preserved. Contrary to LA-PB(-), ALS-D revealed significant reduction of hypoglossal neurons but its pyramidal tract tends to be relatively preserved. These results seem to indicate that LA-PB(-) and ALS-D belong to the same spectrum and consist of subgroups with ub-inclusions and involvement of motor neuron system in common. The involvement of the upper motor neuron system is emphasized in LA-PB(-), while ALS-D accentuates the lower motor neuron system. However, the border between the two group is not always clear and there are patients who can not be definitively classified.

Aged↗

PubMed1997

Motor evoked potentials in the preoperative and postoperative assessment of normal pressure hydrocephalus.

Motor evoked potentials and central motor conduction time (CMCT) were examined from both upper and lower limbs in patients with normal pressure hydrocephalus to find a predictor for the success of shunting procedures. The hypotheses that walking disturbances are due to pyramidal tract compression as well as the possibility that the upper limbs are affected subclinically in these patients were also studied. The study suggests that the walking disturbances are not the result of a major pyramidal tract dysfunction but probably involve the sensorimotor integration leading to normal gait. Furthermore, CMCT measured with electromagnetic motor stimulation can help in selecting the patients that will benefit from shunting. The study does not provide electrophysiological evidence of upper limb involvement in normal pressure hydrocephalus.

Adult↗

PubMed2000

Sensorimotor cortical influences on cuneate nucleus rhythmic activity in the anesthetized cat.

This work aimed to study whether the sensorimotor cerebral cortex spreads down its rhythmic patterns of activity to the dorsal column nuclei. Extracellular and intracellular recordings were obtained from the cuneate nucleus of chloralose-anesthetized cats. From a total of 140 neurons tested (106 cuneolemniscal), 72 showed spontaneous rhythmic activity within the slow (< 1 Hz), delta (1-4 Hz), spindle (5-15 Hz) and higher frequencies, with seven cells having the delta rhythm coupled to slow oscillations. The spindle activity recorded in the cuneate was tightly coupled to the thalamo-cortico-thalamic spindle rhythmicity. Bilateral or contralateral removal of the frontoparietal cortex abolished the cuneate slow and spindle oscillations. Oscillatory paroxysmal activity generated by fast electrical stimulation (50-100 Hz/1-2 s) of the sensorimotor cortex induced burst firing synchronized with the paroxysmal cortical "spike" on all the non-lemniscal neurons, and inhibitory responses also coincident with the cortical paroxysmal "spike" in the majority (71%) of the cuneolemniscal cells. The remaining lemniscal-projecting neurons showed bursting activity (11%) or sequences of excitation-inhibition (18%) also time-locked to the cortical paroxysmal "spike". Additionally, the cerebral cortex induced coherent oscillatory activity between thalamic ventroposterolateral and cuneate neurons. Electrolytic lesion of the pyramidal tract abolished the cortically induced effects on the contralateral cuneate nucleus, as well as on the ipsilateral medial lemniscus. The results demonstrate that the sensorimotor cortex imposes its rhythmic patterns on the cuneate nucleus through the pyramidal tract, and that the corticocuneate network can generate normal and abnormal patterns of synchronized activity, such as delta waves, spindles and spike-and-wave complexes. The cuneate neurons, however, are able to generate oscillatory activity above 1 Hz in the absence of cortical input, which implies that the cerebral cortex probably imposes its rhythmicity on the cuneate by matching the intrinsic preferred oscillatory frequency of cuneate neurons.

Animals↗

PubMed2000

The Babinski sign--a reappraisal.

In 1896, Joseph Babinski, a French neurologist, first described the best known neurologic eponym 'the Babinski sign'. This sign is characterised by dorsiflexion of the big toe and recruitment of the extensor hallucis longus muscle, on stimulating the sole of the foot. He has emphasised from the outset, the intimate relationship between this sign and the shortening movement in other leg muscles, which form the flexion synergy of the lower limb. The Babinski sign is not a new reflex, rather it is released as a result of breakdown of the harmonious integration of the flexion and extension components of the normal defence reflex mechanism, due to pyramidal tract dysfunction. A pathological Babinski sign should be clearly distinguished from upgoing toes that may not always be a part of the flexion synergy. This article reviews the Babinski sign in detail, focusing on the historical perspectives, role of pyramidal tract dysfunction and art of elicitation and interpretation. The significance of assessing this phenomenon in the entire leg, and the clinical clues that will help to dispel the myths regarding the Babinski sign, have been emphasised.

Humans↗

PubMed2003

The Babinski sign--a critical review.

In 1896, Josph Babinski, a French neurologist, first described the best known neurologic eponym--"the Babinski sign". This sign is characterised by dorsiflexion of the big toe, by recruitment of the extensor hallucis longus muscle, on stimulating the sole of the foot. He himself emphasised from the outset the intimate relationship between this sign and the shortening movement in other leg muscles, which forms the flexion synergy of the lower limb. The Babinski sign is not a new reflex, rather it is released as a result of breakdown of the harmonious integration of the flexion and extension component of the normal defence reflex mechanism, due to pyramidal tract dysfunction. A pathological Babinski sign should be clearly distinguished from upgoing toes that may not always be a part of the flexion synergy. This article reviews the Babinski sign in detail, focusing on the historical perspectives, role of pyramidal tract dysfunction, art of elicitation and interpretation. The significance of assessing this phenomenon in the entire leg and the clinical clues that will help to dispel the myths regarding the Babinski sign has been emphasized.

Eponyms↗

PubMed1988

Localisation of the corticospinal fibres in the internal capsule in man.

The myelogenetic development of the corticospinal fibres in the internal capsule was studied using eight brains of the Yakovlev Collection and two brains of the collection in Hannover Medical School. The myelin sheaths of the corticospinal fibres stained by the Loyez method can best be seen in the third postnatal month. During their course through the internal capsule their relative position changes. In the superior portion of the internal capsule, at the level of the interventricular foramen, the pyramidal tract is located in the middle of the posterior limb and in the inferior portion, at the level of the subthalamic nucleus and metathalamus, in the posterior third of the posterior limb. The classical concept of the localisation of the pyramidal tract has, therefore, to be revised for the inferior portion of the internal capsule. The result of this study confirms those of stereotactic, neuropathological and macroscopic observations and underlines the importance of the Yakovlev Collection for the neurosciences.

Child↗

PubMed2000

Visualization of nerve fiber orientation in gross histological sections of the human brain.

Diffusion weighted magnetic resonance imaging (DWMRI) allows visualization of the orientation of the nervous fibers in the living brain. For comparison, a method was developed to examine the orientation of fibers in histological sections of the human brain. Serial sections through the entire human brain were analyzed regarding fiber orientation using polarized light. Direction of fibers in the cutting plane was obtained by measuring the azimuth with the lowest intensity value at each point, and inclination of fibers in the section was evaluated using fuzzy logic approximations. Direction and inclination of fibers revealing their three-dimensional orientation were visualized by colored arrows mapped into the images. Using this procedure, various fiber tracts were identified (pyramidal tract, radiatio optica, radiatio acustica, arcuate fascicle, and 11 more). Intermingled fibers could be separated from each other. The orientation of the fiber tracts derived from polarized light microscopy was validated by confocal laser scanning microscopy in a defined volume of the internal capsule, where the fiber orientation was studied in four human brains. The polarization method visualizes the high degree of intermingled fiber bundles in the brain, so that distinct fiber pathways cannot be understood as solid, compact tracts: Neighbouring bundles of fibers can belong to different systems of fibers distinguishable by their orientation.

Aged↗

PubMed1984

The cytoarchitectonic organization of the spinal cord in the rat. I. The lower thoracic and lumbosacral cord.

A laminar cytoarchitectonic scheme of the lower thoracic and lumbosacral segments of the rat spinal cord is presented in which Rexed's principles for the cat are applied. The material consists of 80-micron-thick sections stained with toluidine blue or according to van Gieson and 2-micron-thick sections stained with p-phenylenediamine or toluidine blue. The cytoarchitectonic organization of the rat spinal cord was found to be basically similar to that of the cat, although certain differences exist--for example, in the extension of the laminae. In addition to the laminar scheme, the distribution of certain cell groups, Lissauer's tract, and the pyramidal tract were investigated.

Animals↗

PubMed2006

Electrophysiological abnormalities precede apparent histological demyelination in the central nervous system of mice overexpressing proteolipid protein.

Myelin proteolipid protein (plp), a major myelin protein in the CNS, has been proposed to function in myelin assembly. Transgenic mice overexpressing the plp gene by introduction of two extra wild-type (Wt) mouse plp genes (plp(tg/-)) exhibit normal myelination and ion channel clustering at the age of 2 months. However, at the age of 5 months, demyelination becomes observable, accompanied by a reduction in the number of K+ channel clusters at Ranvier's node and a progressive increase in motor deficit. To clarify how these age-dependent changes are related to nerve conduction in the CNS, we analyzed the conduction velocity (CV) and relative refractory period (RRP) of identified spinal ascending or descending tracts, such as the dorsal column pathway, the vestibulospinal and reticulospinal tracts, and the pyramidal tract, in plp(tg/-) mice 2, 5, and 8 months of age. We found that CVs decreased as age increased. Importantly, CVs were significantly reduced and prolonged RRPs were observed in 2-month-old (2M) plp(tg/-) mice that had no apparent demyelination. Immunohistological examination revealed that densities of Na+ and K+ channel clusters decreased as plp(tg/-) and Wt mice aged. However, a clear correlation was not observed between CVs and mean channel cluster densities or between mean channel cluster densities and progress of demyelination. Performance in the rotarod test was normal in 2M plp(tg/-) mice but deteriorated in mice older than age 5 months. These results suggest that electrophysiological analysis can detect the abnormalities of the plp(tg/-) mice earlier than histological or behavioral measures.

Animals↗

PubMed1975

[Subacute myelo-optic-neuropathy (S.M.O.N.) following treatment with clioquinol (author's transl)].

2 patients, who were treated with clioquinol after radical resection of carcinoma of the rectum and colostomy, developed symmetrical sensorimotor polyneuropathy, mild posterior tract ataxia, bilateral pyramidal tract lesions and optic neuropathy, a clinical picture compatible with subacute myelo-optic-neuropathy (S.M.O.N.). One patient had neurological symptoms after having received 750 g of clioquinol, 3 years after treatment started, and impairment of vision was noted after having received 1200 g. The other patient had neurological symptoms 6 weeks after clioquinol was first given, having received 65 g, the average daily dose being 1.5 g, and vision was impaired after 765 g had been administered. On examination 12 and 14 months after clioquinol had been discontinued, the first patient's vision was slightly improved, but he was otherwise unchanged, while the vision of the other patient was unchanged, but she had otherwise deteriorated slightly neurologically. Electrophysiological examinations confirmed the clinical observations. A multifactor etiology of the syndrome: neurotoxicity of clioquinol, paraneoplastic neuropathy and malabsorption, is discussed.

Abdomen, Acute↗

PubMed2004

Immediate plasticity in the motor pathways after spinal cord hemisection: implications for transcranial magnetic motor-evoked potentials.

The present study evaluates motor functional recovery after C2 spinal cord hemisection with or without contralateral brachial root transection, which causes a condition that is similar to the crossed phrenic phenomenon on rats. Descending motor pathways, including the reticulospinal extrapyramidal tract and corticospinal pyramidal tracts, were evaluated by transcranial magnetic motor-evoked potentials (mMEPs) and direct cortical electrical motor-evoked potentials (eMEP), respectively. All MEPs recorded from the left forelimb were abolished immediately after the left C2 hemisection. Left mMEPs recovered dramatically immediately after contralateral right brachial root transection. Corticospinal eMEPs never recovered, regardless of transection. The facilitation of mMEPs in animals that had undergone combined contralateral root transection was well correlated with open-field behavioral motor performance. Both electrophysiological and neurological facilitations were significantly attenuated by the selective serotonin synthesis inhibitor para-chlorophenylalanine (p-CPA). These results suggest that serotonergic reticulospinal fibers located contralateral to hemisection contribute to the behavioral and electrophysiological improvement that immediately follows spinal cord injury (SCI).

Animals↗

PubMed1999

Spinal cord injury after electrical trauma treated in a burn unit.

OBJECTIVE: To analyse the incidence, diagnosis and outcome of spinal cord injury in patients with electrical injuries. PATIENTS AND METHODS: Retrospective analysis of patients with electrical injuries admitted to our Intensive Care Burn Unit over a 5 year period. Among 435 admissions, 57 (13.1% of all admissions) were electrical injuries, due to either electrical flash (n = 34) or high voltage (n = 23). Two cases (8.6% of high voltage injuries) presented signs of spinal cord injury. Both cases presented an acute transverse myelopathy, involving the pyramidal tract, the posterior cords and the spinothalamic tract, causing a pyramidal syndrome with abnormal sensation and involvement of posterior cords, one with paraplegia and the other one with quadriplegia. Diagnoses were made 1 and 2 weeks after admission, respectively, when sedation was discontinued and neurological signs could be appreciated. Computerised axial tomography and nuclear magnetic resonance were normal in both cases at the moment of diagnosis. Both patients experienced a slow but progressive improvement of their neurological condition, and remain presently in a rehabilitation program 15 and 18 months after trauma. DISCUSSION: Our cases illustrate (i) that damage to the spine is not infrequent after electrical injury, (ii) the difficulty in making the diagnosis of spinal cord injury after electrical trauma, and (iii) the importance of early diagnosis to define neurological prognosis and start available therapies as soon as possible.

Adolescent↗