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Interaction of tonic labyrinth and neck reflexes was studied in 3 healthy volunteers by analyzing changes in Soleus H-Reflex (SHR) area in relation to both lateral tiltings and neck rotations. By using a Kermath chair each subject was tilted laterally from the vertical to the left and to the right up 15° in steps of 5° and at the same time the longitudinal body axis, keeping the head fixed, was rotated to the right and to the left up to 15° in steps of 5°. All combinations of lateral tiltings and neck rotations were tested. Each test position was followed by a return to 0° for both rotation and tilting (control position). Twelve H-reflexes of right soleus muscle were recorded in each test and control position and the changes in RSHR area were expressed as percentage variations from the mean value absorved in the pretest and post-test control position. Out data indicate that in man, as in animals, labyrinth and neck reflexes act in the opposite direction, and that in the static condition their contribution to postural stabilization is equal. Al fine di studiare nell'uomo le interazioni reciproche dei riflessi tonici labirintici e tonici del collo abbiamo analizzato le variazioni dell'area del riflesso H del muscolo soleo indotte da diverse combinazioni di rotazione del collo ed inclinazioni laterali dell'asse corporeo su 3 soggetti volontari sani. Dalla posizione verticale venivano inclinati lateralmente verso destra e verso sinistra di 5° in 5° fino ad un massimo di 15° e contemporaneamente veniva ruotato l'asse corporeo, tenendo il capo fisso, di 5° in 5° fino ad un massimo di 15°. In ciascun soggetto venivano studiate tutte le possibili combinazioni di inclinazioni e rotazioni. Ogni posizione test veniva fatta seguire da una posizione di controllo a 0° (capo in posizione primaria ed asse corporeo verticale). In ciascuna posizione test e di controllo venivano registrati 12 riflessi H e di ciascuno si misurava l'area. I valori ottenuti nelle diverse posizioni test venivano espressi come percentuale della media dei valori osservati nella corrispondente posizione di controllo precedente e successiva. I risultati così ottenuti indicano che nell'uomo, come nell'animale, i riflessi tonici labirintici e tonici del collo agiscono esercitando sul tono estensorio dell'arto inferiore azioni opposte e di entità sovrapponibile.

Experimental studies in monkeys have demonstrated that injection of gamma-aminobutyric acid (GABA) agonists into the superior colliculus restricts saccadic eye movements, while injection of GABA antagonists leads to square-wave jerks (SWJ). To investigate the role of GABA in saccadic interruptions of fixation, we treated five patients who had SWJ and square-wave oscillations (SWO) with valproic acid (VPA) (2000 mg/d), which has been shown to increase brain GABA levels. VPA effectively reduced the SWJ/SWO in three patients, abolished them in one patient, but was ineffective in the fifth, who had a localized lesion in the cerebellar vermis. VPA effects may have been due to the restoration of the GABAergic tonic inhibitory action from the substantia nigra pars reticulata to the superior colliculus.

A Sardinian pedigree described in 1964 for having been found to segregate at the X-linked loci for the Xga antigen, G6PD deficiency, Protan and Deutan color blindness, with an instance of recombination between the last two loci, was re-examined with respect to four common X-linked DNA polymorphisms detected by molecular probes homologous to critical subregions of the human X chromosome. Two branches of this pedigree-including the one with the Protan-Deutan recombinant-were found to segregate also for the common BamHI polymorphism identified with the cDNA probe pHPT-2 of the HPRT gene (Xq26). The analysis of the chromosome haplotypes in the male offspring of the phase known penta-heterozygous mother suggests that the probable order of the relevant loci is HPRT, Deutan, G6PD, Protan, Xq telomere. Though we are fully aware of the risks of generalizing the significance of observations made on a single exceptional pedigree, we believe that this report outlines the potential of families of the type described as reasearch tools to resolve the linear order of tightly X-linked loci and to investigate the biology of genetic recombination in humans.

A patient with progressive supranuclear palsy exhibited an extremely high number of square wave jerks. These usually sporadic saccadic intrusions were so frequent as to form a continuous oscillation. Such a phenomenon suggests an underlying commonality between sporadic saccadic intrusions (square wave jerks, saccadic pulses and double saccadic pulses) and saccadic oscillations (macro square wave jerks, MSO and flutter).

In Wilson's disease neurological manifestations result from the damage in the basal ganglia, even if a widespread degeneration of the brain occurs. The few studies performed using evoked potentials with the aim of identifying subclinical dysfunction in the three major sensory pathways have never shown abnormalities in patients without neurological manifestations. To verify this observation we studied 12 patients suffering from Wilson's disease in a pre-neurological stage by using pattern visual evoked potentials (VEPs), somatosensory evoked potentials (SEPs) to median nerve stimulation and brainstem auditory evoked potentials (BAEPs). Four of these patients had not yet been treated with penicillamine or trientine (triethylenetetramine dihydrochloride), while the remaining 8 patients were on treatment for at least 1 year. In 3 patients of this second group and in 1 patient of the first group we observed a significant (3 SD over the mean) increase in P100 wave latency, while SEPs and BAEPs were found to be abnormal in only 1 patient, respectively.

Our previous study of 31 cases of manifest latent nystagmus (MLN) suggested a one-to-one relationship between the occurrence of MLN and the presence of strabismus. This study of three patients with both latent nystagmus (LN) and MLN has elucidated the relationship between strabismus and these two intimately related types of nystagmus. Both LN and MLN have jerk waveforms whose fast phases are in the direction of the fixating eye and whose slow phases are decreasing-velocity exponentials; the nystagmus is simultaneously present in the two eyes. LN and MLN should not be confused with congenital nystagmus which differs in waveform, variability with gaze angle, mechanism, clinical signs and therapy. During binocular viewing, if the two eyes are aligned with normal retinal correspondence, the patient with true LN will have no nystagmus. Only if one of his eyes assumes a tropic position, might MLN develop. Under cover, the development of a phoria is synchronous with the occurrence of LN. Thus, strabismus in the form of a tropia or a phoria emerges as a necessary, but not sufficient, condition for both LN and MLN. That is, during the time when a nystagmus is present, the non-fixating eye (the eye behind cover or which is being suppressed) will be phoric or tropic, respectively. In LN cases with abnormal retinal correspondence, although no nystagmus may be present with the eyes in their normal fixed tropic position, cover will induce nystagmus along with a phoria. The intriguing and highly desirable possibility of converting MLN to LN, in a very young child with a fixed tropia, by early strabismus surgery is discussed.

Abstract. Saccadic trajectories were examined in ten young normal subjects for amplitudes of 5,15,30, and 40 deg. Multiple saccades (m) and discrete decelerations (dd) were seen not in conjunction with any fatigue effect but rather as a function of amplitude, being much more frequent at larger amplitudes. The presence of m and dd in the large saccades of normals and in even small refixations of patients with myasthenia and Eaton-Lambert syndrome suggests that they are a normal consequence of high innervation levels.

Quantitative eye movement recordings in a patient with suspected multiple sclerosis who had alternating esotropia, horizontal nystagmus and downbeat nystagmus showed occasional monocular macro square wave jerk intrusions and oscillations in the fixating eye during spontaneous monocular fixation, and binocular macro square wave jerk oscillations during the effort to fuse. Base-out (converging) prisms suppressed nystagmus, oscillopsia, and macro square wave jerks, and restored normal binocular function.

Infrared oculographic recordings of saccades evoked by auditory or visual targets in four patients with hemianopia due to an occipital lesion showed that these patients employed a different strategy to find visual and auditory targets in each hemifield. In the seeing hemifield, the patients acquired auditory targets with both monosaccadic and multiple saccadic refixations. The first saccade, the largest, brought the eyes toward the target; the following smaller saccades completed the search as in normal subjects. Saccades to visual targets consisted of one orthometric saccade or two saccades. By contrast, in the blind hemifield the patients acquired auditory targets by a staircase strategy consisting of stepwise saccadic search movements similar to those used for visual targets in the same hemifield. The similarity of strategy to auditory and visual targets suggests a common motor program controlled by the visual input. The latency, accuracy, and velocities of visual and acoustic responses were equal in both hemifields.

Carbamazepine (CBZ) brain uptake was determined in cats rendered epileptic by administration of 250,000 IU penicillin/kg intramuscularly, and the results were compared with those in a control group. CBZ penetration in the brain was significantly different in the epileptic cats, the uptake of the drug in the generalized epileptic brain being decreased and delayed, although substantial binding occurred also in this case. Plasma and CSF levels behaved similarly in normal and epileptic cats. Arguably the impaired CBZ brain uptake was due to the epileptic activity itself, which per se can be responsible for marked inhibition of protein synthesis, thus modifying the proven ability of CBZ to bind to phospholipid and protein components of neuronal cells.

We treated 3 multiple sclerosis patients who had pendular nystagmus with isoniazid (800 to 1,000 mg/d). Isoniazid abolished the nystagmus and relieved oscillopsia in 2 patients but was ineffective in the 3rd in whom the nystagmus was damped with convergence and vision improved with converging (base-out) prisms.

A boy with a left-hemispheric cerebellar astrocytoma had upbeat nystagmus exhibiting increasing-velocity slow phases. The nystagmus improved after excision of the tumour.