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PubMed2005

Behr syndrome variant with tremor treated by VIM stimulation.

Behr syndrome was first described in 1909 as a syndrome of heredofamilial optic atrophy, visual disturbances, nystagmus, and variable pyramidal tract signs. The syndrome has been reported in both sexes. So far, tremor has not been reported to be part of Behr Syndrome. We present the case of a 51-year-old man with a rare complicated dominant inherited cerebellar ataxia with accompanying visual loss and tremor (CICALVT) resembling a Behr Syndrome variant who suffered from advanced visual deterioration since childhood and progressive spastic paraparesis for 15 years. Furthermore, the patient presented increasing tremor of both hands for 5 years. The successful treatment of the tremor using deep brain stimulation (DBS) of the ventral intermediate thalamic nucleus (VIM) is reported. Our case indicates that deep brain stimulation of the ventral intermediate nucleus is an adequate operative intervention that can help to reduce tremor even in patients with complicated movement disorders.

Deep Brain Stimulation↗
PubMed1999

Prediction of the post-comatose motor function by motor evoked potentials obtained in the acute phase of traumatic and non-traumatic coma.

OBJECTIVE: To define the value of electrically elicited motor evoked potentials (MEP), obtained during the initial phase of the coma, for correct prediction of the post-coma motor status. METHODS: Fifty-two patients were investigated by MEP within 72 hours after onset of the coma. It was the aim to correlate the MEP findings to the motor function two months after coma onset. RESULTS: Three patients with normal MEP showed no post-coma motor deficit. In 21 patients, a bilateral, symmetric prolongation of the central motor conduction time (CMCT) was registered. Eighteen of these 21 patients (86%) showed a normal post-coma motor status. In 28 patients, unilaterally absent evoked potential, or unilaterally prolonged CMCT, or bilaterally prolonged CMCT with significant difference in each hemisphere were observed. A post-coma contralateral paresis was found in 25 of these 28 patients (89%). That paresis was functionally important in 15 patients (54%) and functionally unimportant in 13 patients (46%). CONCLUSION: We identified certain MEP patterns (unilateral extinction of the evoked potential, unilateral, bilateral prolongation of the CMCT with significant "side" difference), which indicated a pyramidal tract lesion and a post-coma motor deficit with an accuracy of 89%. This refers to the motor results, which may not be the final post-coma motor results which are usually assessed six months after the coma onset. The MEP changes did not allow one to predict the severity of the paresis. The accuracy of prediction of a motor deficit increased from the MEP finding of unilaterally prolonged CMCT to the MEP finding of unilateral extinction of the potential. The most common finding, bilateral central motor slowing without significant "side" difference, did not indicate a post-coma paresis in 86%, leading to the assumption, that bilateral, symmetrical prolongation of the CMCT was not caused by lesions of the descending motor pathways, but by the drugs administered for treating the comatose patient. In conclusion, MEP allows one to predict the presence of a post-coma motor deficit with a high degree of accuracy already in the initial phase of coma, but MEP fails to predict the severity of that deficit.

Acute Disease↗
PubMed2004

Presence of HTLV-I Tax protein in cerebrospinal fluid from HAM/TSP patients.

Infection with human T-cell lymphotropic virus type I (HTLV-I) have been associated with the development of the HTLV-I-associated myelopathy/Tropical Spastic Paraparesis (HAM/TSP). The disease affects the pyramidal tract at the distal segments of spinal cord, generating a spastic paraparesis. We studied the presence of Tax protein in cerebrospinal fluid cells and spinal fluid (CSF) of 35 Chilean patients: 22 HAM/TSP patients (15 HTLV-I-seropositives, and 7 seronegatives), and 13 controls (9 PSP and 4 CJD non-infected patients). Tax antigens were evaluated with monoclonal antibodies reacting with Tax by immunofluorescence and ELISA assays in cerebrospinal fluid cells and CSF, respectively. Proviral was evaluated by PCR of tax gene in cerebrospinal fluid cells. Tax antigen was detected in CSF and lymphocytes of CSF from 4 and 12 HAM/TSP patients, respectively. Lymphocytes of CSF of 8 HAM/TSP (6 seropositives and 2 seronegatives) showed the presence of tax gene. These results show that cells of CSF from HAM/TSP patients are able to express and export Tax protein towards the CSF. This is the first report of the presence of Tax protein in cerebrospinal fluid cells and CSF from HAM/TSP HTLV-I seronegative patients.

Adult↗
PubMed2005

Multimodal electrophysiologic follow-up study in 3 mutated but presymptomatic members of a spinocerebellar ataxia type 1 (SCA1) family.

The objective was to determine the progression of nervous system involvement in spinocerebellar ataxia type 1 (SCA1). Three presymptomatic members of an Italian SCA1 family underwent molecular analysis and showed the SCA1 mutation. They were defined as "at risk/mutated" individuals. A clinical and electrophysiologic 7-9 year follow-up was performed. The Inherited Ataxia Progression Scale was used for clinical staging. Sensory and motor conduction velocities, somatosensory evoked potentials and transcranial magnetic stimulation were performed at least three times in each subject. Clinical examination showed the early corticospinal pathway involvement. Electrophysiologic investigations confirmed that at the asymptomatic stage only magnetic motor cortex stimulation was abnormal and rapidly worsened with time. Somatosensory pathway studies showed a later involvement and a light sensory-motor neuropathy was the last electrophysiologic abnormality to be recognised. These data confirm that SCA1 phenotype is characterised by early and prevalent pyramidal tract involvement and that peripheral neuropathy is a late and moderate complication.

Adult↗
PubMed2007

Combined motor and somatosensory evoked potentials for intraoperative monitoring: intra- and postoperative data in a series of 69 operations.

The primary objective of neurophysiologic monitoring during surgery is to avoid permanent neurological injury resulting from surgical manipulation. To prevent motor deficits, either somatosensory (SSEP) or transcranial motor evoked potentials (MEP) are applied. This prospective study was conducted to evaluate if the combined use of SSEP and MEP might be beneficial. Combined SSEP/MEP monitoring was attempted in 100 consecutive procedures, including intracranial and spinal operations. Repetitive transcranial electric motor cortex stimulation was used to elicit MEP from muscles of the upper and lower limb. Stimulation of the tibial and median nerves was performed to record SSEP. Critical SSEP/MEP changes were defined as decreases in amplitude of more than 50% or increases in latency of more than 10% of baseline values. The operation was paused or the surgical strategy was modified in every case of SSEP/MEP changes. Combined SSEP/MEP monitoring was possible in 69 out of 100 operations. In 49 of the 69 operations (71%), SSEP/ MEP were stable, and the patients remained neurologically intact. Critical SSEP/ MEP changes were seen in six operations. Critical MEP changes with stable SSEP occurred in 12 operations. Overall, critical MEP changes were recorded in 18 operations (26%). In 12 of the 18 operations, MEP recovered to some extent after modification of the surgical strategy, and the patients either showed no (n = 10) or only a transient motor deficit (n = 2). In the remaining six operations, MEP did not recover and the patients either had a transient (n = 3) or a permanent (n = 3) motor deficit. Critical SSEP changes with stable MEP were observed in two operations; both patients did not show a new motor deficit. Our data again confirm that MEP monitoring is superior to SSEP monitoring in detecting impending impairment of the functional integrity of cerebral and spinal cord motor pathways during surgery. Detection of MEP changes and adjustment of the surgical strategy might allow to prevent irreversible pyramidal tract damage. Stable SSEP/MEP recordings reassure the surgeon that motor function is still intact and surgery can be continued safely. The combined SSEP/ MEP monitoring becomes advantageous, if one modality is not recordable.

Adolescent↗
PubMed1975

Functional significance of projection from the cerebellar nuclei to the motor cortex in the cat.

The functional organization of projections from the cerebellar subcortical nuclei to the motor cortex through the nucleus ventralis lateralis (VL) of the thalamus was studied using tungsten microelectrodes for stimulation and recordings in acute and chronic cats. The following results were obtained. (1) Microstimulation of a small area of the ventral thalamus produced contraction of a single limb muscle as well as movements of whiskers. (2) The stimulus parameters for producing low threshold contraction of limb muscles were different from those for face muscles. The decrease of the frequency gradualy increased the threshold values for face muscles whereas the decrease abruptly increased the threshold for limb muscles. The optimum duration of the train for the lowest thresholds was longer for face muscles. (3) Stimulation of cerebellar nuclei (interpositus and lateralis) produced contraction of limb muscles. The stimulus parameters for the minimum threshold were similar to those for producing contraction of limb muscles from the ventral thalamus. (4) The peripheral receptive fields of neurons located around the low threshold sites in the thalamus were diffuse, i.e. they were driven insecurely by twisting the joints or pressure to the deep structures, but could not be driven by touch or light pressure on a circumscribed area of the body. (5) Chronic ablation of the motor cortex did not abolish the muscle contractions produced by thalamic stimulation, excluding the possibility that the effects were produced by stimulation of the branches of the pyramidal tract fibers reaching the ventral thalamus. (6) Chronic section of the brachium conjunctivum abolished or changed the characteristics of the contractions produced by thalamic stimulation indicating that the previous effects were produced by stimulation of cerebellar efferent fibers reaching the thalamus. (7) From these results it was concluded that the efferent impulses originating from the cerebellar nuclei can produce contraction of a particular muscle through activation of the red nucleus. These impulses are, at the same time, transmitted to a small group of neurons in the VL and then forwarded to the neurons in the motor cortex. (8) The functional significance of the VL projection system has been discussed in relation to the efferent zones within the motor cortex.

Animals↗
PubMed1981

Characteristics of the ipsilateral movement-related neuron in the motor cortex of the monkey.

The characteristics of the precentral neuron activity related to ipsilateral movements were studied while the monkey was performing finger, wrist and arm movements on either side. Out of 197 task-related neurons, 134 discharged in association with contralateral movements, but not with any one of 3 ipsilateral movements. Fifty neurons discharged with bilateral movements. Thirteen neurons discharged in association with ipsilateral movements (ipsi-neurons). Ten were recorded from the trunk or shoulder area of the motor cortex and were accompanied by contraction of those muscles by intracortical stimulation (ICS). The remaining 3 were related to elbow or wrist, but no ipsi-neurons were related to finger muscle contractions. In ipsilateral task performance, 7 ipsi-neurons discharged in association with finger and/or wrist movements in addition to arm movement. Five others were associated with arm movement. The last one discharged with wrist movement. Most of the units showed similar response to contralateral movement. Ipsi-neurons were classified into two groups. One group was recorded around the sulcus precentralis superior, had the lower threshold current and was mostly associated with finger, wrist and arm movements. The other was recorded in the rostral motor cortex, and had the higher threshold current and was related to arm movement. Among 185 neurons to which pyramidal tract stimulation was delivered, 2 out of the 80 PTNs and 11 out of the 105 non-PTNs were ipsi-neurons. EMGs were recorded from various muscles involved in the forelimb movements. Arm and finger muscles showed no activity when the monkey used the ipsilateral hand, while most of the shoulder and trunk muscles showed tonic or moderate transient changes in the activity during the ipsilateral tasks. The ipsi-neuron activity was discussed in consideration with EMGs.

Animals↗
PubMed1981

Effect of oxotremorine on local cerebral glucose utilization in motor system regions of the rat brain.

The [14C]2-deoxy-D-glucose technique was used to test the effects of central muscarinic stimulation on local cerebral glucose utilization (LCGU) in rats. Systemic administration of the muscarinic agonist oxotremorine (OXO, 0.7 mg/kg, ip) increased LCGU in brain regions involved in motor function: the sensorimotor cortex; the extrapyramidal motor system, including the striatum, globus pallidus, red nucleus, substantia nigra, subthalamus and ventral nucleus of the thalamus; the cerebellar vermis, fastigial nucleus and nucleus interpositus; and the vestibular nucleus. No effects were observed in the fibers of the pyramidal tract, internal capsule, cerebellar white matter and the dentate nucleus. Increases were not affected by methylatropine (1 mg/kg sc), but were completely antagonized by scopolamine (2.5 mg/kg, ip). The anatomic distribution and magnitude of the LCGU response to OXO were not simply correlated with the reported densities of muscarinic receptors.

Animals↗
PubMed1982

Operant conditioning of single unit activity in parietal cortex.

Two rhesus monkeys were trained to control firing patterns of single neurons in parietal cortex (areas 1, 2, 3, 5, 7) using an operant task previously applied to the study of precentral units. Twenty-four of 56 (43%) postcentral cells were controlled in contrast to 71 of 136 (52%) precentral units from these and 4 other rhesus monkeys. In addition, monkeys were able to drive precentral units to more sustained tonic firing rates than they could parietal units. An analysis of interspike interval (ISI) distributions showed that, in contrast to precentral units with modal ISIs of 25-50 ms, 50% of parietal units have modal ISIs of 2 ms. Such short ISIs may account for fewer postcentral units reaching control criteria for this particular operant task. Other factors that may contribute to the reduced control of postcentral cells are discussed, particularly the more complex afferent connections to parietal units when compared to precentral pyramidal tract neurons. The data indirectly support conclusions from previous studies that imply that operant control of cortical units is peripherally mediated and does not primarily involve a 'central' or 'open loop' system.

Action Potentials↗
PubMed1982

Participation of corticothalamic cells in penicillin-induced generalized spike and wave discharges.

Single unit extracellular recordings were performed in the cortex of awake painlessly immobilized unanesthetized cats during generalized spike and wave discharges (SW) induced by i.m. penicillin. Corticothalamic cells were identified in cortical areas 3a and 4 gamma by stimulating n. ventralis lateralis (VL) and in cortical areas 5 and 7 by stimulating n. lateralis posterior (LP). Twelve of 24 neurons antidromically invaded from VL were also pyramidal tract cells. Two of 11 neurons antidromically invaded from LP also displayed orthodromic responses. Corticothalamic cells fired bursts of action potentials in association with the 'spike' whereas a period of inhibition was associated with the 'wave' of the SW complex. The data suggest that in this experimental model the appearance of SW in the thalamus is due to secondary activation of thalamic neurons by volleys arising from the cortex and mediated through corticothalamic connections.

Animals↗
PubMed1983

Recovery of locomotor function in cats after localized cerebellar lesions.

Cats were trained to walk on a motorized treadmill, at speeds up to a brisk walk, for food reward. A cerebellar lesion was placed in each animal, either unilateral removal of paravermal cortex, or unilateral coagulation of n. interpositus, or bilateral coagulation of the fastigial nuclei. The effects of these lesions upon locomotor activity were measured by conventional kinematic methods, and were found to be generally in agreement with prior observations. Also in agreement with prior work was the fact that these initial deficits disappeared in a relatively short time. The kinematic data suggest that this recovery of function was genuine in the sense that compensatory alterations in limb motion could not be demonstrated. In disagreement with prior studies, we failed to elicit decompensation (e.g. reinstatement of the original deficits) by subsequent pyramidal tract sections, or ablation of the 'motor' cortex. We conclude that the corticospinal system is probably not essential to the recovery observed, and also that perhaps there are substantial differences in the mechanisms of recovery of 'spontaneous' overground locomotion, compared to walking on a treadmill as a conditioned instrumental response.

Adaptation, Physiological↗
PubMed1985

Morphological and electrophysiological study of sprouting of corticorubral fibers after lesions of the contralateral cerebrum in kitten.

The appearance of crossed corticorubral projections following ablations of the ipsilateral cortex is shown to result from the formation of new connections and is not due to the preservation of pre-existing bilateral connections. At least some of these crossed projections are collaterals of the pyramidal tract. Post-tetanic potentiation can be demonstrated both intra- and extracellularly following ipsilateral cerebral peduncle stimulation whereas no changes in excitatory postsynaptic potential amplitude are observed following contralateral cerebral peduncle stimulation.

Animals↗
PubMed1985

Hypothalamic projections to the ventral medulla oblongata in the rat, with special reference to the nucleus raphe pallidus: a study using autoradiographic and HRP techniques.

Hypothalamic descending projections to the medullary ventral surface were studied autoradiographically in the rat. A small amount of [3H]leucine was injected unilaterally into various parts of the hypothalamus by air pressure. Abundant and characteristic terminal labelings were observed bilaterally in the nucleus raphe pallidus, the ventral surface of the pyramidal tract and the nucleus interfascicularis hypoglossi, after injections into the dorsal posterior hypothalamic area caudal to the paraventricular hypothalamic nucleus. Conspicuous, but less numerous labelings were observed in the nucleus raphe obscurus and the ipsilateral raphe magnus. After an injection of [3H]leucine into the hypothalamus and injections of horseradish peroxidase (HRP) into the spinal cord in the same animal, silver grains were densely distributed around HRP-labeled neurons in the nucleus raphe pallidus including the nucleus interfascicularis hypoglossi. The present results suggest that the dorsal posterior hypothalamic area projects directly to the spinal-projecting neurons of the nucleus raphe pallidus.

Animals↗
PubMed1986

Calcineurin as a neuronal marker of human brain tumors.

Calcineurin is one of the calmodulin binding proteins and a Ca2+-dependent and calmodulin-stimulated phosphoprotein phosphatase. We used antisera to the calcineurin as a cell-type-specific marker in order to identify neuronal cells in the rat brain and human neoplasms. In normal rat brain slices, basal ganglia were stained macroscopically, and other areas such as cerebral cortex, corpus callosum, cerebellar cortex, granular layer and pyramidal tract of the spinal cord were lightly identified as well. Under the light microscope, it was found that only the neuronal cells were stained, and astrocytes, oligodendrocytes, ependymal cells and vessels were not. Intracellular distribution of the staining showed various patterns and staining intensity of varying degree. Using the PAP method, localization of the calcineurin in formalin-fixed, paraffin-embedded tissues were studied in 65 human intracranial neoplasms, and in 11 human extracranial neoplasms. The neuronal elements of neuroblastoma, ganglioglioma, ganglioneuroma and retinoblastoma were clearly stained. In contrast, glioblastoma, astrocytoma, oligodendroglioma, ependymoma, meningioma, neurinoma, pituitary adenoma, craniopharyngioma, hemangioblastoma, hamartoma, lymphoma and mesenchymal tumor were all negative. Two cases out of 5 medulloblastomas were stained, but others were not. Although positive tumors disclosed various staining patterns and intensities, these results indicated that calcineurin could be a new neuronal marker in human brain tumors.

Animals↗
PubMed1987

Substance P-containing medullary projections to the intermediolateral cell column: identification with retrogradely transported rhodamine-labeled latex microspheres and immunohistochemistry.

Substance P (SP)-containing medullary neurons that project to the intermediolateral cell column (IML) of the rat were studied. Neurons were retrogradely labeled with rhodamine-labeled latex microspheres (RITC-M) injected into the T-3 IML, and SP-immunoreactive neurons were identified with immunocytochemistry. RITC-M labeled cells occurred in the nucleus reticularis paragigantocellular lateralis (RPgcl), adjacent and lateral to the pyramidal tract at the level of the rostral inferior olivary nucleus and extended to the mid-facial nucleus in the medulla. Cells were also labeled caudal to the RPgcl, in the nucleus reticularis ventralis, pars alpha (RVa), rostral to the RVa, in the nucleus reticularis gigantocellularis (RGc), and in the raphe nuclei. SP immunoreactivity (SP-IR) was seen in cells that were also retrogradely labeled. These double-labeled cells were observed in the RPgcl, RVa and the raphe pallidus. These data show that the IML receives SP-neuronal projections from multiple locations in the medulla. The SP-neuronal projections from the RPgcl of the ventral medulla to the IML likely represent one component of the ventral medullary region that influences cardiovascular functions.

Animals↗
PubMed1987

Mechanism of aminopyridine-induced ictal seizure activity in the cat neocortex.

Intracellular recordings were obtained from neurons in the motor cortex of anesthetized cats in order to examine membrane and synaptic processes involved in aminopyridine (AP)-induced ictal seizure activity. Depolarizing and hyperpolarizing membrane potential sequences which behaved as large, synchronized excitatory and inhibitory postsynaptic potentials, were found to accompany the ictal seizure potentials. After several repetitions of the seizure attack, partial responses, bursts and depolarizing plateaus with spike inactivation occurred. In layers IV and V we found non-pyramidal tract neurons showing endogenous bursting ability activated by AP. These neurons seemed to be the initiators of the rhythmic synchronous activity of the epileptic neuron population. Our results suggest that AP-induced epileptogenesis represents an adequate model of ictal events in the neocortex.

Action Potentials↗
PubMed1987

Excitatory and inhibitory effects on respiration of L-glutamate microinjected superficially into the ventral aspects of the medulla oblongata in cat.

L-Glutamate (4-40 nmol) was microinjected at superficial depths beneath the ventral surface of the medulla oblongata in cats. Injections (100-300 microns beneath the surface) made rostromedial to the hypoglossal nerve, less than 1.5 mm lateral to the pyramidal tract, caused stimulation of phrenic nerve activity. Injections (100-500 microns beneath the surface) up to 1 mm further lateral caused a marked increase in arterial pressure and depression of phrenic nerve activity. These findings support the existence of two cell groups in the ventral medulla that are involved in regulation of respiration; when activated, one (medial group) causes facilitation and the other (lateral group) inhibition of respiration.

Animals↗
PubMed1988

Intracellular injection of apamin reduces a slow potassium current mediating afterhyperpolarizations and IPSPs in neocortical neurons of cats.

Electrophysiologic effects of intracellularly injected apamin, a Ca2+-dependent K+ channel blocker, were investigated in neurons of the motor cortex of awake cats. Single-electrode voltage clamp techniques were used to measure changes in membrane currents including those that were synaptically activated. All changes occurred within 2-4 min after pressure injection of apamin with partial recovery observed within 8-15 min. Apamin selectively abolished an outward current that mediated a slow afterhyperpolarization (AHP) following intracellular depolarizing current pulses and action potentials without influencing the time course of the action potentials or an associated fast AHP component. In addition apamin increased the number and frequency of spike discharges evoked by the depolarizing current pulses and produced a small increase in the rate of background firing activity. The baseline resting potential and input resistance were essentially unchanged by apamin. Apamin also diminished a late, slowly decaying component of inhibitory postsynaptic potentials (IPSPs) and currents (IPSCs) elicited by stimulation of the ventrolateral thalamus or the pyramidal tract. The apamin-induced changes were concomitant with a decrease of the decay time constant of both IPSPs and IPSCs and a positive shift in their reversal potential. The results suggest that the late, slowly decaying component of these inhibitory postsynaptic responses is generated by an apamin-sensitive Ca2+-dependent K+ conductance which is also responsible for the slow AHP.

Action Potentials↗