Unlike the numerous dispersed bulbospinal pathways that are already well myelinated at term, the more compact corticospinal and corticobulbar tracts are only beginning their myelination cycle in late gestation and do not complete it until two years of age. During this same period, these pathways also develop extensive ramification of terminal axonal segments, growth of collateral axons, and proliferation of synapses. Despite their immaturity in the fullterm human newborn, several proposed functions may be attributed to the descending pathways from the neonatal cerebral cortex: a) a contribution to the differential development of passive muscle tone and resting postures; in general they function as an antagonist to the “subcorticospinal pathways” in mediating proximal flexion and distal extension, except for the rubrospinal tract which is probably synergistic with the corticospinal tract; b) enhancement of tactile reflexes originating in the brainstem and spinal cord, including suck and swallow; c) relay of epileptic activity of cortical origin; d) inhibition of complex stereotyped motor reflexes including many phenomena formerly termed “subtle seizures”; e) a possible influence on muscle maturation, particularly in relaying cerebellar impulses that modify the histochemical differentiation of myofibres. However, the bulbospinal tracts are probably more influential on muscle development. The corticospinal and corticobulbar tracts subserve different needs in the newborn than at older ages, but are functionally important pathways even at birth.

The effects of traumatic brain injury (TBI) and aging were compared on tests of simple and complex reaction time (RT). Simple RT was not significantly affected by aging or TBI. TBI patients, however, tended to be slower on Simple RT tasks, and had a larger standard deviation. Individuals over age 60 and patients of any age with TBI demonstrated slower RT with choice RT tests. In addition, both groups (those over 60 and TBI patients) were less able than other groups to inhibit the processing of redundant information. For the TBI patients, this occurred primarily on reassessment. These results suggest that the deficit in both aging and TBI is not only a generalized neuronal slowing but a more specific impairment in attentional control processes, exhibited as a deficit in focused attention.

We describe an ultra-high resolution technique for recording evoked potentials (EPs) that are thousands of times smaller than the total EEG power. We report that two superimposed visual stimulus patterns, one modulated at F1 Hz and the other at F2 Hz , can generate 20 or more EP frequency components, each of which is contained within a bandwidth of no more than 0.004 Hz. We have developed a theoretical method for calculating the amplitudes and phases of these various cross-modulation components for different arrangements of model neurons. The relative amplitude of the various cross-modulation components seems to be a 'signature' of the particular neural model and this offers a way of testing theoretical neural models against EP data. As an illustration we compare the nonlinear EP components evoked by dichoptic stimulation with unpatterned flickering light against several models of binocular interaction. These nonlinear binocular interaction terms may offer a means of investigating binocularity in amblyopic children or infants who have low acuity in one or both eyes.

We assessed parkinsonian rigidity objectively at the wrist to determine the optimal angular velocity and displacement for detecting abnormality. The wrist was moved passively with a torque motor and the average work done for one complete cycle was computed. This objective rigidity score (ORS) was compared with a clinical rigidity score (CRS). ORS was more pronounced at faster movement velocities in parkinsonian patients, whereas in normal subjects there was only a modest increase in the score. Angular velocities of 140 to 190 degrees/second and displacements of ±25 to ±30 degrees were most sensitive for detecting parkinsonian rigidity and had good correlation with the CRS.

High iron concentrations have been reported in the brains of multiple sclerosis victims. To determine if there are abnormalities in general iron metabolism indicative of iron overload in MS, measurements of transferrin saturation, serum ferritin and red cell ferritin in 31 female and 18 male patients were compared to the results in 49 age- and sex-matched healthy controls. Compared to controls, mean serum ferritin in MS was high, whereas transferrin saturation and red cell ferritin were similar. High values in one or more individual test results were observed in eleven MS patients. They were prevalent in patients who required bilateral assistance to walk or were confined to a chair, and appeared to be related to the severity of the disease. An investigation was made into the relationship of the high serum ferritin values in MS to the HLA-A3 histocompatibility antigen, a marker of the hemochromatosis gene which is prevalent in MS. A statistically significant interaction was not found between serum ferritin and the presence of HLA-A3.

Twenty-five patients with long-standing therapy resistant epilepsy were studied in an eight-month double- blind cross-over add-on trial with a daily dose of 15 mg flunarizine. In five patients the seizure frequency decreased 50% or more. The mean seizure frequency reduction in the patients on flunarizine was 35%. Particularly the control of secondary generalized seizures improved. Flunarizine did not significantly alter the plasma levels of the regular anticonvulsant drugs. Minimal adverse side effects were reported equally in the flunarizine and the placebo group. In three patients depressive symptoms improved and two patients became free of postictal headaches. Flunarizine appears to be a safe adjuvant anticonvulsant.

We report a double blinded cross-over study involving Flunarizine versus placebo in the treatment of refractory childhood epilepsy. The patients studied were between the ages of 2 and 18; and were having more than 4 seizures per month not responsive to regular anticonvulsant medications. Of the 34 patients treated, 8 had a 50% decrease in their seizures during the placebo phase, 5 had a 50% decrease during the Flunarizine phase, and 1 patient had a 50% increase in seizures while taking Flunarizine. The remaining 25 patients showed no change in seizure activity in either phase. Patients having partial seizures with secondary generalization tended to do better on Flunarizine than those with other seizure types. Monitoring serum Flunarizine levels showed no significant difference between patients having improved seizure control and those who were unimproved. No significant side effects were noted with this medication, nor were any significant drug interactions noted.

A thirty-eight-year-old man presented with a six year history of symptoms resembling an anterior horn cell disorder. There was progressive upper extremity wasting and weakness in the absence of sensory complaints. Electrophysiologic abnormalities were confined to motor nerve conduction and indicated a demyelinating process involving the brachial plexus and major proximal upper extremity nerve trucks bilaterally. Biopsy of the proximal right ulnar nerve revealed changes suggesting a chronic demyelinating process, and onion-bulb formations were present. Immunohistochemical staining for S-100 protein was positive in the cells comprising the onion-bulbs, indicating a Schwann cell, not a perineurial origin of these cells. After 8 years, symptoms have failed to appear in the lower limbs. Recent reports in the literature have begun to delineate the syndrome, which appears to represent an unusual, localized or multifocal, sometimes inflammatory, clinically benign neuropathy that can mimic motor neuron disease in its earlier stages. We report the first such case with underlying pathology.

A 57 year old man developed bilateral hypoglossal nerve palsies 6 years after radiotherapy for carcinoma of the uvula. Follow-up over 2 years has demonstrated no evidence of tumour recurrence and no sign of neurological improvement. Reactive fibrosis and vascular insufficiency secondary to radiation and may have lead to hypoglossal nerve compression and infarction.

An unusual case of Progressive Multifocal Leukoencephalopathy (PML) in a Haitian man with AIDS is reported. The lesions involving both white and gray matter are described radiologically and at post-mortem. The implications regarding neuroradiological differential diagnosis in AIDS as well as PML virulence in this type of patient are discussed.

Anosognosia is a well-known manifestation of non-dominant parietal lobe lesions and typically lasts a few days. That anosognosia may last only a few minutes to a few hours, as observed in six patients, has not been reported. In five patients, transient anosognosia for equally brief left-sided hemiparesis was a manifestation of transient ischemic attacks (TIAs). In the sixth patient, anosognosia for both a left-sided motor seizure and a subsequent brief left hemiparesis could best be explained by an epileptic ictal and post-ictal transient dysfunction of the non-dominant parietotemporal cortex. Prompt recognition of transient anosognosia, whether ischemic or epileptic, is mandatory for proper diagnosis and for rapid initiation of specific therapy.

intraparenchymal solitary cyst of the medulla oblongata was diagnosed on MRI examination in a 66-year-old woman with a nine year history of progressive brainstem dysfunction and three negative CT scan examinations. Craniotomy and drainage of the cyst to the IVth ventricle led to remarkable clinical recovery. Biopsy of the wall of the cyst revealed an epithelial lining with tonofilaments, desmosomes and surface coating on ultrastructural examination. Immunohistochemistry demonstrated positive reactions of epithelium for keratins, cytokeratins, epithelial membrane antigen and Ulex Europeus lectin, indicating endodermal origin of the cyst.

Cerebral edema associated with meningiomas is a rather common phenomenon. A patient with a small meningioma presented with severe cerebral edema, out of proportion to the size of the tumor. During surgery the meningioma was removed and the adjacent edematous brain tissue biopsied. The histopathoiogical study showed conspicuous plasma cell and lymphocyte infiltration in both the tumor and the cerebral edematous tissue. The pathological findings are presented, and the possible mechanism for cerebral edema associated with meningioma is discussed.

The results of 3 computed tomography (CT) examinations carried out over a 7 year period and of a post-mortem magnetic resonance (MR) study showed aspects of a white matter disease in a hypertensive patient suffering from vascular dementia. Histopathology revealed the primary cause of dementia to be a white matter degeneration sparing the U fibers. Rarefaction of both the myelin sheaths and the axons was present together with severe thickening of the medullary arteries. These findings support the existence of Binswanger's disease (BD) as a distinct variety of arteriosclerotic dementia. CT and MR imaging are valuable aids for diagnosis. However, since there are many other causes of CT and MR demonstrated diffuse white matter degeneration in the elderly, a conclusive diagnosis of BD requires pathological confirmation.