Tremor-related motor unit firing in Parkinson's disease: implications for tremor genesis

Muscle tremors reflect rhythmical motor unit (MU) activities. Therefore, the MU firing patterns and synchrony determine the properties of the parkinsonian force tremor (FT) and the neurogenic components of associated limb tremors. They may also be indicative of the neural mechanisms of tremor genesis which to date remain uncertain. We examined these MU behaviours during isometric contractions of a finger muscle in 19 parkinsonian subjects. Our results reveal that the parkinsonian FT is abnormally large. Like the physiological FT, it is accompanied by in-phase rhythms in all MU activities. However, there exist two important differences. Firstly, the synchrony during the parkinsonian FT is stronger than the normal one and therefore contributes to the FT enhancement. Secondly, the synchronous MU components partly represent rhythmical sequences of spike doublets and triplets whose incidences directly reflect the differences of the MU firing rates to the FT frequency. According to our analyses, the latter frequency coincides with the MU recruitment rate. Consequently, the numerous medium- and small-sized active MUs contribute rhythmical twitch doublets and triplets, i.e. large force pulses, to the parkinsonian FT. The impact of this effect on the FT amplitude is found to predominate over the impact of the augmented synchrony. Importantly, apart from the rule governing the occurrence of doublets/triplets, the mean interspike intervals within such spike events are fairly fixed around 50 ms. Such regularities in MU activities may reflect properties of the neural input underlying the FT, and thus represent a basis for more focused studies of the generator(s) of parkinsonian tremors.

Foot rotation contribution to trunk and gaze stability during whole-body mediated gaze shifts: a principal component analysis study

Large gaze displacements are mediated by combined motion of the eye, head, trunk, and foot. We applied principal component analysis (PCA) to examine the degree of variability and linearity in the angular velocity pattern of the various segments involved that participate in this task. Ten normal subjects stood up and had to visually fixate and realign their bodies with LED targets separated 45 degrees apart, ranging from +/-45 to 360 degrees. The outbound movement in this paradigm is unpredictable whereas the return (inbound) movement occurs under spatially predictable conditions. Under such predictable conditions, subjects generate in approximately 15% of the trials gaze shifts, with periods of fairly constant high gaze velocity (single-step gaze shifts). PCA showed that gaze velocity variability did not change if the feet were rotating or not. Foot velocity was variable and showed additional PCs suggestive of non-linear motion components. Trunk and head-in-space velocity showed intermediate levels of variability but its variability decreased during the foot stepping movements. The results suggest that the feet, trunk, and head are less tightly controlled by the central nervous system than gaze velocity. Movements of the feet seem to aid trunk stability and motion rather than gaze control.

[The concept of time and its relation to the psychoanalytic-psychotherapeutic setting]

Psychoanalysis is fundamentally related to time because it is an ef for t to understand how disturbances in the present are determined by events in the past. This paper represents an attempt to delineate the developmental line of time sense from birth to object constancy, concentrating on those maturational and environmental factors which determine psychotemporal adaptation in infancy and early childhood until the age of adolescence. Patients' distortions of time can frequently and readily be observed in clinical psychoanalysis reflecting both their psychopathology and their reactions to the temporal aspects of the psychoanalytic setting.

A minute demyelinating lesion causing acute positional vertigo

Clinico-anatomical correlations in multiple sclerosis patients presenting with central positional vertigo are lacking. We report on a patient with acute onset positional vertigo mimicking benign paroxysmal positional vertigo with a single enhancing lesion in the inner part of the superior cerebellar peduncle, disclosed only after thin slice MR-imaging. This location appears to be a common cause of central positional vertigo and should be regarded as characteristic for demyelinating rather than vascular pathology. In cases presenting with positional nystagmus and vertigo without other cerebellar deficits one should look explicitly for signal abnormalities in the inner part of the superior cerebellar peduncle. High spatial resolution-MRI seems to be mandatory for lesion detection.

[Benign paroxysmal positional vertigo with and without manifest positional nystagmus: an 18-month follow-up study of 70 patients]

BACKGROUND

In this follow-up study of approximately 18 months we assessed parameters of medical management in a sample of 70 patients suffering from benign paroxysmal positional vertigo.

METHODS

Apart from demographic data, we evaluated the time interval from the appearance of the first symptoms until a diagnostic positional manoeuvre was performed, the efficacy of liberatory manoeuvres, the prescription of medication, the use of technical diagnostic resources and the relapse rate.

RESULTS

None of the patients had received a diagnostic positioning test until then. Moreover, in one out of three cases a further unnecessary technical diagnostic procedure was carried out. There was a tendency for the right labyrinth to be more frequently affected, a fact that was statistically independent from age and sex, as well as from overall prognosis, which was characterized by a 15.6% recurrence rate. All patients with manifest positional nystagmus were successfully treated: 87.2% immediately after the repositioning manoeuvre and the rest within 10 days by self-performing Brandt-Daroff exercises. Our retrospective analysis revealed that, given a normal neuro-otological examination, a typical medical history without manifest positioning nystagmus leads safely to the correct diagnosis.

CONCLUSION

The delay between the onset of symptoms and the diagnosis of BPPV is very often unduly long. A focused medical history may be diagnostic even in the absence of nystagmus during the Dix-Hallpike manoeuvre.

Positional nystagmus and vertigo due to a solitary brachium conjunctivum plaque

The authors describe two patients suffering from demyelinating central nervous system disease who developed intense vertigo and downbeat nystagmus upon tilting their heads relative to gravity. Brain MRI revealed in both cases a single, small active lesion in the right brachium conjunctivum. The disruption of otolithic signals carried in brachium conjunctivum fibres connecting the fastigial nucleus with the vestibular nuclei is thought to be causatively involved, in agreement with a recently formulated model simulating central positional nystagmus. Insufficient otolithic information results in erroneous adjustment of the Listing's plane in off-vertical head positions, thus producing nystagmic eye movements.

Smooth pursuit rather than visual signals mediate short-term adaptation of the cervico-ocular reflex in humans

Cervical stimulation in the horizontal plane induces small and variable eye movements in normal human adults [cervico-ocular reflex (COR)]. In patients with bilateral vestibular loss, the slow COR component increases in amplitude and is thought to contribute to gaze stabilization during head movements, as it is directed opposite to head-on-trunk excursions. The procedures underlying COR slow phase gain enhancement in the compensatory direction remain unclear. We studied the horizontal COR during passive trunk oscillations of +/-16 degrees under the stationary head at 0.1 Hz in ten normal subjects, aged 24-30 years, before and immediately after the application of an adaptation procedure engaging various combinations of sinusoidal neck-proprioceptive, pursuit and retinal slip signals. The duration of this adaptation period was 40 min. A significant gain increase and phase modulation in the compensatory direction were observed in four out of eight subjects after exposing them to neck-proprioceptive stimulation, while pursuing a spot moving in-phase with their trunk. In contrast, staring at the rotating optokinetic pattern or fixating at a stationary spot, while being subjected to combined cervical and optokinetic stimulation, failed to result in any significant modification of the subjects' COR gain and phase. Conceivably, the contribution of the pursuit system was greatly reduced in the paradigm using optokinetic stimulation, while full engagement of retinal slip signals, in the absence of any pursuit contribution, was obtained in the latter adaptation paradigm. These results indicate that motor responses of target tracking rather than simply sensory signals of retinal slip may represent the 'error signal' modifying the COR in humans.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) in a Greek family

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an adult-onset inherited disease, characterised by recurrent strokes, migraine and cognitive impairment. We present the first Greek family with CADASIL, caused by the R153C mutation at exon 4 of the Notch3 gene. A member of this family carrying this mutation was also found to be heterozygotic for the MTHFR mutation, factor V Leiden mutation and had low serum levels of antithrombin III, thus resulting in the appearance of recurrent strokes and thrombotic episodes since his early adulthood. The co-existence of these thrombophilic disorders with CADASIL in a single person poses serious therapeutic dilemmas, as the administration of anticoagulant agents may correlate with increased risk of potentially fatal intracerebral haemorrhage.

Guillain-Barré syndrome in a patient with metastatic colon cancer receiving oxaliplatin-based chemotherapy

We report Guillain-Barre syndrome (GBS), developed in a patient with metastatic colon cancer, receiving oxaliplatin-based chemotherapy. The 53-year-old patient was treated with first-line chemotherapy consisting of oxaliplatin 45 mg/m2, 5-fluorouracil 450 mg/m2 and folinic acid 200 mg/m2, all given on the same day in a weekly schedule. After 13 weeks of treatment and a cumulative oxaliplatin dose of 585 mg/m2, the patient developed unsteadiness of gait, dysphagia, and weakness of both the upper and lower limbs, as well as impairment of all sensory modalities. Clinical examination, computed tomography and magnetic resonance imaging scans of the brain, blood tests, nerve conduction studies, and cerebrospinal fluid analysis confirmed the diagnosis of GBS. Intravenous immunoglobulin G was administered for 5 days and the patient recovered fully. Oxaliplatin can cause acute and delayed neurotoxicity, but this is the first report of GBS in a patient receiving oxaliplatin-based chemotherapy. Elevation of pro-inflammatory cytokines, such as tumor necrosis factor-alpha and interleukin-6, induced by oxaliplatin, may represent the relevant causal links involved in the cascade of events which have led to the immune-mediated demyelination in the peripheral nervous system in this patient.

Eye position signals modify vestibulo- and cervico-ocular fast phases during passive yaw rotations in humans

We studied the amplitude, latency, and probability of occurrence of fast phases (FP) in darkness to unpredictable vestibular and/or cervical yaw stimulation in normal human subjects. The rotational stimuli were smoothed trapezoidal motion transients of 14 degrees amplitude and 1.25 s duration. Eye position before stimulus application (initial eye position, IEP) was introduced as a variable by asking the subjects to fixate a spot appearing either straight ahead or at 7 degrees eccentric positions. The recordings demonstrated that the generation of FP during vestibular stimulation was facilitated when the whole-body rotation was directed opposite the eccentric IEP. Conversely, FP were attenuated if the whole-body rotation was directed toward the eccentric IEP; i.e., the FP attenuated if they were made to further eccentric positions. Cervical stimulation-induced FP were small and variable in direction when IEP was directed straight ahead before stimulus onset. Eccentric IEPs resulted in large FP, the direction of which was essentially independent of the neck-proprioceptive stimulus. They tended to move the eye toward the primary position, both when the trunk motion under the stationary head was directed toward or away from the IEP. FP dependence on IEP was evident also during head-on-trunk rotations. No consistent interaction between vestibularly and cervically induced FP was found. We conclude that extraretinal eye position signals are able to modify vestibularly evoked reflexive FP in darkness, aiming at minimizing excursions of the eyes away from the primary position. However, neck-induced FP do not relate to specific tasks of stabilization or visual search. By keeping the eyes near the primary position, FP may permit flexibility of orienting responses to incoming stimuli. This recentering bias for both vestibularly and cervically generated FP may represent a visuomotor optimizing strategy.

Proprioceptive influence on the optokinetic nystagmus

The influence of neck and leg proprioceptive inputs on optokinetic-induced quick phases was studied in humans. Ten subjects received unidirectional horizontal optokinetic stimulation (10-20%/s) during sinusoidal neck, leg and combined neck + leg proprioceptive stimulation. The optokinetic reflex was measured by electro-oculography. Neck stimulation induced a shift in the nystagmus beating field in the opposite direction to body movement (gain 0.3 0.4, phase 140-180 degrees). The beating field shift resulted totally from the amplitude and frequency modulation of optokinetic quick phases, as slow phases were not affected. Leg proprioceptive stimulation induced a similar effect, but the phase of the response lagged by approximately 90 degrees compared with that of neck response. With combined neck + leg stimulation, the amplitude of the effect was a sum of the separate effects, but the phase coincided with that of the leg response. This suggests that neck and leg proprioceptive signals do not add linearly and that the leg signal determines the time of the response.

A patient with essential thrombocytosis and multiple sclerosis

We report on a patient with a 5-year history of essential thrombocytosis (ET) who developed multiple sclerosis (MS) during the last 5 months. The patient was treated for MS with interferon-beta (IFN-beta), which also had a beneficial effect on the ET. We describe the patient's history and the beneficial effect of IFN-beta administration in reducing the number of platelets. We also discuss the possible link between the pathogenesis of ET and MS.

A case of thalamic syndrome: somatosensory influences on visual orientation

The ability to set a straight line to the perceived gravitational vertical (subjective visual vertical, SVV) was investigated in a 21 year old woman with long standing left hemihypaesthesia due to a posterior thalamic infarct. The putative structures involved were the somatosensory and vestibular thalamus (VPL, VPM) and associative (pulvinar) thalamus. The SVV was normal when seated upright. When lying on her right side, line settings deviated about 17 degrees to the right, which is the normal A-effect. When lying on the hypaesthetic side the mean SVV remained close to true vertical-that is, the A-effect was absent, and there was a large increase in variability of the SVV settings. The findings support the view that the body tilt-induced bias of the SVV (A-effect) is largely mediated by somatosensory afferents. The finding that the A-effect was absent only when lying on the hypaesthetic side suggests that, during body tilt, the somatosensory system participates in visuogravitational orientation.

Weekly docetaxel in minimally pretreated cancer patients: a dose-escalation study focused on feasibility and cumulative toxicity of long-term administration

BACKGROUND

Docetaxel is an agent with impressive clinical activity but a rather poor profile of toxicity when given every three weeks. Therefore, optimisation of its clinical use is highly warranted. This is a dose-escalation study of weekly docetaxel particularly focused on the feasibility of long-term administration and characterisation of cumulative toxicity.

PATIENTS AND METHODS

Twenty-six patients (11 female/15 male, median age 56, range 23-73) were treated over the range of 25-50 mg/m2/week. Dose-limiting toxicity for this schedule was defined as any grade > 2 antiproliferative toxic effect resulting in a > 2-week delay for re-administration of the drug, or any grade > 2 organ-specific toxicity. Patients were monitored clinically and electrophysiologically for neurotoxicity. No prolonged corticosteroid co-medication or prophylactic haematopoietic growth factors were given.

RESULTS

A median/mean number of 8.5/8.7 consecutive weekly courses were given per patient. The maximum tolerated dose that prevented on-schedule administration of the drug was 50 mg/m2. The main cumulative toxicities were a mild fluid retention and dacryorrhea which became evident as the number of treatment courses increased. Grade 2 alopecia and fatigue were observed only at 45 mg/m2 and higher. Activity was seen at all of the dose levels studied.

CONCLUSIONS

Long-term weekly administration of docetaxel is feasible at doses up to 45 mg/m2/week with acceptable toxicity. Further clinical evaluation is justified at this schedule and 40 mg/m2/week of docetaxel is proposed for phase II studies as an active dose with minimal toxicity.

Deletions in the Parkin gene and genetic heterogeneity in a Greek family with early onset Parkinson's disease

Parkinson's disease is the second most common neurodegenerative disease after Alzheimer's disease and is manifested as a movement disorder. A positive family history is the second most important risk factor for developing the illness, after age. Both autosomal dominant and recessive forms of the illness have been described. Recently deletions in a novel gene, parkin, have been associated with the autosomal recessive form of the illness in Japanese families. In this study, we demonstrate that deletions of exons 5, 6 and 7 of the parkin gene are present in two affected individuals of a Greek pedigree with early onset Parkinson's disease. However, no deletions were identified in a different branch of the same pedigree with three affected individuals. These results suggest that deletions in the parkin gene will be found in other families besides those of Japanese origin and that there must be at least one additional locus responsible for early onset autosomal recessive Parkinson's disease.

Smooth pursuit eye movements and otolith-ocular responses are differently impaired in cerebellar ataxia

Horizontal and vertical smooth pursuit was compared with otolith-ocular responses in 11 patients with cerebellar ataxia and 21 normal subjects using three-dimensional magnetic search coil eye movement recordings. Otolith-ocular responses were investigated during off-vertical axis rotation. This stimulus induces nystagmus consisting of the exponentially decaying canalicular response, and an eye-velocity modulation and offset which arise from the excitation of the otoliths by the gravity vector, which lasts as long as the rotation continues. Otolith-ocular reflexes are intimately interrelated with visual tracking when real targets are viewed during linear motion. The responses of both the translational vestibulo-ocular reflex and the pursuit system have been shown to be linearly dependent on the inverse of the viewing distance, so that a common central pathway for the two systems has been suggested, probably travelling through the cerebellum. Thus, the aim of the study was to evaluate to what extent these reflexes are disturbed in cerebellar disease. The results confirm the earlier notion that in normal subjects pursuit performance is better for horizontal than for vertical tracking, and that it is better for upward than for downward tracking. This pattern is also found in patients. In addition, smooth pursuit performance is clearly degraded in patients, but the modulation of eye-velocity during off-vertical axis rotation is enhanced. Since the amount of this enhancement does not correlate with the amount of pursuit impairment, degradation of smooth pursuit and pathological enhancement of otolith-ocular responses seem to be independent effects of cerebellar degeneration. Thus, the increase in the otolith-ocular response in patients cannot be attributed to adaptational mechanisms trying to overcome the smooth pursuit deficiency; it is more likely to represent pathological disinhibition of otolith derived responses. The absence of compensatory eye-velocity offset during off-vertical axis rotation may reflect the fact that in patients the otolith signals are not utilized in computations thought to be important for spatial orientation mechanisms arising from the interaction of vestibular, visual and somatosensory signals.

Vestibular memory-contingent saccades involve somatosensory input from the body support

Humans use vestibular head-in-space information when redirecting gaze towards remembered target location in space. This study shows that neck input is also involved. Normal subjects performed saccades towards remembered locations in space of a previously seen target following passive horizontal rotations of the head or trunk. Saccades based on vestibular input alone fell short at low stimulus frequencies. Addition of neck input modified the responses, making them more accurate when the head was rotated on the stationary trunk. The results support a concept according to which vestibular input is channeled via proprioceptive coordinate transformations through the haptically perceived body support before yielding a sense of head motion in space. The loop is also involved in the saccadic gaze mechanism.

Opposite rotation induced by dopamine agonists in rats with unilateral lesions of the globus pallidus or substantia nigra

Normal rats with a unilateral ibotenic acid lesion of substantia nigra pars reticulata (SNR, n = 12) or globus pallidus (GP, n = 12) were challenged systemically with the mixed dopaminergic agonist apomorphine (0.5 and 1.5 mg/kg) and the indirect acting d-amphetamine (1.5 mg/kg). The low dose of apomorphine produced a weak contralateral rotation only in the SNR-lesioned group, which showed an intense ipsilateral rotation following the administration of the higher dose. GP-lesioned rats also showed ipsilateral rotation after the high dose of apomorphine. d-Amphetamine produced ipsilateral rotation in GP-lesioned rats, contrasting with a vigorous contralateral rotation in SNR-lesioned rats. The unexpected opposite rotation after apomorphine and d-amphetamine, observed only in SNR-lesioned animals, indicates that the role of SNR in basal ganglia functions is less clear and more complex than what is expected from our current model of basal ganglia circuitry and functions. On the other hand, the GP lesion resulted in a consistent and predictable ipsilateral rotation after both apomorphine and d-amphetamine, indicating a more determinant effect on the output of the basal ganglia than heretofore believed. Our results may contribute to the recently expressed views challenging the established model of basal ganglia organisation.

What is straight ahead to a patient with torticollis?

Vestibular and neck proprioceptive signals are known to be used in judging the locations of objects in space and relative to the body. Given that these signals are asymmetric in patients with spasmodic torticollis, one would expect such patients to have abnormal spatial perception. We tested this idea by measuring patients' perception of visual straight ahead (VSA) under various conditions: with the body in its primary position, i.e. with the head and trunk as closely aligned as possible, and after well defined passive rotations of the head and/or trunk. In the primary body position, patients' VSA direction showed considerable variations which were similar, however, to those of normal subjects; it was independent of torticollis direction, of the head torque it produced, and of the weak spontaneous nystagmus recorded in seven of the 10 patients. After whole-body rotations, i.e. where head and trunk underwent the same motion, the VSA was shifted in both patients and normal subjects, and in both groups the shift was symmetrical after rotations to the right or left. After motions where the trunk rotated under the stationary head (neck proprioceptive stimulation) or the head on the stationary trunk (combined vestibular and neck stimulus), the VSAs of normal subjects coincided rather well with their head midsagittal planes, whereas the VSAs of patients were shifted considerably towards the trunk, again in a symmetrical way. We suggest two mechanisms to explain the findings in patients: (i) a central compensation which restores symmetry of the afferent inflow in the patients (unlike the motor efference); (ii) shifting of the reference for the VSA from the head towards the trunk, because the trunk is a more reliable egocentric reference than the head in the patients. Our findings do not support the assumption that asymmetries in afferent inflow are responsible for the asymmetry of motor output in spasmodic torticollis.

Dissociation between the perception of body verticality and the visual vertical in acute peripheral vestibular disorder in humans

Estimates of the subjective visual and postural vertical were obtained from five patients with acute peripheral vestibular lesions and 20 normal subjects. The visual vertical was assessed by asking the subjects to align a target line to earth vertical by means of remote control. Postural vertical judgments were obtained by exposing them to rotational displacements in the roll plane while sitting on a motor-driven chair and requiring them to align their body to vertical using a joystick control. While the patients showed strong deviations of the visual vertical towards the lesion side, their postural vertical judgments remained veridical. We conclude that the above perceptions are not processed identically and that the participating sensory systems are differently weighted during these tasks.

Perception of spatial orientation in spasmodic torticollis. Part 2: The visual vertical

Twenty-nine patients with idiopathic spasmodic torticollis (ST) and matched normal control subjects were asked to align a target line to perceived earth vertical [visual vertical (VV)]. Settings were made against a whole-field random-dot background that was either stationary or rotating around the line of sight, and subjects performed the task upright and lying horizontally on their sides. Normal subjects were tested both head upright and after assuming a voluntary head tilt. Patients with ST set the VV close to true upright with a minimal deviation toward tilt of the head in contrast to normal subjects assuming a head tilt who set the VV in the opposite direction to the head tilt (Müller "E" effect). Settings against the spinning disk were biased in the direction of rotation similarly for both subject groups. Settings made against static or spinning disk performed when subjects lay horizontally were tilted in the direction of recumbence (Aubert "A" effect) similarly for both subject groups. When attempting to set the target line parallel to the long axis of the face, patients with head tilt set the line to upright, whereas normal subjects correctly estimated their tilts. One hypothesis offered to explain these results is that the patients referenced only their upright trunk for vertical and did not make use of neck proprioceptive or vestibular signals of head tilt so that all settings were made as if the trunk and head were upright. Alternatively, patients may have used only otolith signals as the reference for upright, and these are recalibrated in ST patients with head tilt. The pathological deviation becomes accepted as upright posture, and VVs and facial orientation are estimated as if the head were upright. In either case the findings indicate abnormal processing of the perception of visual verticality in ST patients.

Horizontal otolith-ocular responses to lateral translation in benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo (BPPV) is assumed to result from utricular damage, but it is controversial if patients have manifest utricular dysfunction. Therefore, we investigated linear vestibulo-ocular reflexes (LVORs) during lateral whole-body translation in 14 patients with unilateral BPPV. Patients were subjected to linear acceleration steps of 0.24 g along the interaural axis, which were applied randomly to the left and right, both in the dark and in the light with a visual target at a distance of 60 cm. The LVOR was measured by EOG from the slow phase velocity of the averaged and desaccaded compensatory eye movement. In normal cases, maximum asymmetry of LVOR velocity was 13% in the dark and 10% in the light. In patients, LVOR velocities were normal in the dark but mildly reduced in the light (p < 0.05). Five patients had mild LVOR asymmetries in the dark (range 18-38%) and two in the light (11 and 13%), but there was no consistent relationship to the affected side. The absence of gross changes of the LVOR may be explained either by minor utricular damage that is functionally irrelevant or by central compensation of a chronic unilateral deficit.

Perception of spatial orientation in spasmodic torticollis. Part I: The postural vertical

Estimates of points of entering and exiting from upright posture were obtained from 25 seated, restrained patients with idiopathic spasmodic torticollis (ST) and matched normal subjects exposed to cycles of 1.5 degrees/s tilts in a flight simulator. Estimates were obtained for displacements in roll and pitch about upright and for yaw tilts about a rostrocaudal, "barbecue," axis with the subjects supinated. For both pitch and roll, normal subjects estimated entering upright when they were still approximately 1 degree from machine upright and perceived themselves to be upright through a mean arc of 6 degrees. In barbecue tilt, entering upright was estimated at 0.2 degree for an arc of 6 degrees. Patients estimated entering upright at 2.8 degrees in roll and 3 degrees in pitch but estimated exiting upright at the same tilt as normal subjects; that is, they were less specific in detecting verticality. Patients were normal in barbecue tilt. No relationship between tilt estimates and head deviation was found. There were no differences between normal subjects when tested with their head in normal posture and with an assumed tilt of 20 degrees. Normal subjects probably based their estimates on combined vestibular-somatosensory signals, whereas torticollis patients appeared to derive more from a vestibular signal. However, patients referred the vestibular signals to the trunk long axis when asked to indicate the whole-body vertical. The findings suggest disruption of the normal combined vestibuloproprioceptive mechanism for detecting body uprightness in ST.

Postural responses to vibration of neck muscles in patients with idiopathic torticollis

Vibration of the dorsal muscles of the neck, simulating lengthening, in standing man causes a visible forwards tilt of the body shown on posturography as a tonic sagittal sway deviation. According to the theory that posture is organized with respect to a 'body schema' this deviation is a result of an interpretation of the concurrent neck afferent and vestibular signals. Considering the hypothesis that neck afferent signals may be misinterpreted in patients with spasmodic torticollis (ST) causing abnormal postural responses, we recorded body sway induced by unilateral dorsal neck muscle vibration in 22 idiopathic ST patients (19 treated with botulinum toxin) during upright stance with eyes closed. Comparison groups were 19 normal subjects and 11 patients with bilateral loss of vestibular function (labyrinthine defective, LD) in whom neck afference should be intact. Both treated and untreated ST and LD patients had absent or diminished sway deviations. When sway deviation did occur, it was sagitally oriented as with normal subjects and unrelated to ST head turns. In most ST and LD patients, neck vibration induced neck extension, an effect which is observed in normal subjects only if the torso is retrained. The results suggest that neck proprioceptive input retains local postural functions in ST, however, it is relatively ignored in the context of the whole body postural control and spatial orientation. The mild disorders of vestibular function reported in torticollis patients may be due to an inability to calibrate vestibular signals by reference to corroborative signals from neck proprioception.

Effect of carpal tunnel syndrome on median nerve proximal conduction estimated by F-waves

Slowing of median nerve proximal motor conduction in patients with carpal tunnel syndrome (CTS) could be considered as an indicator of an additional proximal lesion (double crush syndrome). The effect of CTS on proximal conduction was assessed by comparing motor velocities calculated by F-waves obtained from muscles with the same root and nerve supply but different median branches, one emerging before the carpal tunnel (pronator quadratus muscle) and one passing through the tunnel (abductor pollicis brevis). Data were obtained from 26 patients with CTS and 21 age-matched healthy subjects. In the control group, the proximal (spinal cord and elbow) F-wave maximal velocity calculated when recording from abductor pollicis brevis (FCVmax-APB) was not different from the F-wave maximal velocity calculated when recording from pronator quadratus (FCVmax-PQ), while it was significantly different in the group of CTS patients, especially in patients with terminal motor latency greater than 4.5 ms (approximately 9% less, p = 0.001, Wilcoxon signed rank test). The study showed that median nerve proximal conduction velocity slowing in patients with CTS is restricted to the fibers that distally pass through the carpal tunnel and does not necessarily imply an additional proximal lesion. We suggest that comparison of FCVmax-APB and FCVmax-PQ could be useful when the question arises if a single (distal) or two (one distal, one proximal) lesions are responsible for a patient's symptoms.

Psychosocial problems and adjustment of children with beta-thalassemia and their families

This study explores the psychosocial problems experienced by families with children aged 6 to 14 years suffering from beta-thalassemia major (N = 188). The psychosocial problems and the family's adjustment to the effects of the illness were compared across a number of cultures where the disease is prevalent, namely Cyprus, Greece, and Italy. A small number of migrant children in the United Kingdom was also included in the study. Semi-structured interviews were conducted with parents who also completed the Rutter Parental Questionnaire and the Goldberg General Health Questionnaire. Teachers were asked to complete a Children's Behaviour Questionnaire designed by Rutter. In all countries the disease seemed to have a binding effect on the family, thus mobilizing adaptive mechanisms. Father's low education level and the presence of major medical complications were predictors of poor family adjustment. Differences between and within countries may well reflect differences in health policies, existing level of socio-economic development, and in the cultural patterns in coping with a chronic illness.

Abnormalities of ocular motility in myotonic dystrophy

Are the oculomotor disturbances in myotonic dystrophy (MD), i.e. reduced smooth pursuit (SP) gain and reduced saccadic peak velocity (PV), of muscular or central origin? To answer this question the following two approaches were used. (i) The performance of SP was compared with the patient's ability to suppress the vestibulo-ocular reflex (VOR) visually (VOR suppression; VOR-S). In the latter task the SP system is involved, but the eyes hardly move within the orbits. A parallel impairment of SP and VOR-S would indicate a central dysfunction. (ii) Peak saccadic velocity was compared between two saccades performed to and fro in rapid succession. The intention was to measure any myotonic effect which might build up after the first saccade and slow down the second saccade. We studied 15 MD patients and 15 age-matched controls. Stimuli for slow eye responses consisted of sinusoidal horizontal rotations of the SP target and/or the vestibular rotation chair at frequencies between 0.1 and 0.8 Hz. Saccades were analysed in terms of PV. accuracy, duration and latency, comparing centripetal versus centrifugal saccades at short and long intersaccadic intervals (ISI; 400 ms and 900 ms, respectively). The SP gain was reduced in patients compared with the controls, the effect being most pronounced (32% less) at the highest stimulus frequency. Whereas VOR was normal in the patients, VOR-S was clearly impaired (50% worse at 0.8 Hz). Despite normal saccadic accuracy, peak saccadic velocity was significantly lower in the patient group (23% less for saccades of 12 degrees amplitude), similarly for centrifugal and centripetal saccades; all these differences were independent of the ISI. Latency was normal with centrifugal saccades, but was considerably increased with centripetal saccades at short ISI (67% longer compared with controls). The observation of a parallel degradation of SP and VOR-S in the patients is interpreted in terms of a central deficit in the SP pathways. Thus, it appears that slow eye movements were not impaired by muscle dystrophy and myotonia to a considerable degree in our patients. The increase in saccadic latency for centripetal saccades at the short ISI also reflects a central deficit. However, the observed slowing of saccades might have a myopathic or neural origin; a distinction was not possible at present. A myotonic origin of the saccade slowing seems unlikely, because the effect was independent of the presaccadic activation of the relaxing (antagonistic) eye muscle.

The perception of body verticality (subjective postural vertical) in peripheral and central vestibular disorders

The perception of body verticality (subjective postural vertical, SPV) was assessed in normal subjects and in patients with peripheral and central vestibular lesions and the data were compared with conventional neuro-otological assessments. Subjects were seated with eyes closed in a motorized gimbal which executed cycles of tilt at low constant speed (1.5 degrees s-1), both in the frontal (roll) and sagittal (pitch) planes. Subjects indicated with a joystick when they entered and left verticality, thus defining a sector of subjective uprightness in each plane. The mean angle of tilt (identifying a bias of the SPV) and the width of the sector (defining sensitivity of the SPV) were then determined. In normal subjects, the angle of the "verticality' sector was 5.9 degrees for pitch and roll. Patients with bilateral absence of vestibular function, patients with vertigo, i.e. acute unilateral lesions, benign paroxysmal positional vertigo (BPPV) and Ménière's disease, and patients with positionally modulated up-/downbeat nystagmus all had enlarged sectors (i.e. loss in sensitivity). Mean sector angle in these groups ranged from 7.8 to 11 degrees and the abnormality was present both in pitch and roll, regardless of the direction of nystagmus or body sway. Patients with chronic unilateral peripheral vestibular lesions and those with position-independent vertical nystagmus had normal sensitivities. No significant bias of the SPV was found in any patient group, not even those with acute unilateral vestibular lesions who had marked tilts of the subjective visual vertical (SVV). Complementary experiments in normal subjects tested under galvanic vestibular or roll-plane optokinetic stimulation also failed to show biases of the SPV. In contrast, a significant bias in the SPV could be induced in normal subjects by asymmetric cycles of gimbals tilt, presumably by proprioceptive adaptation. The following conclusions can be drawn. (i) The perception of body verticality whilst seated is mainly dependent on proprioceptive/contact cues but these are susceptible to tilt-mediated adaptation. (ii) Vestibular input improves the sensitivity of the SPV, even in vestibular disorders, as long as the abnormality is stable. (iii) There can be marked dissociation between vestibulo-motor (ocular and postural) phenomena and the perception of body verticality, and between the SPV and SVV. (iv) The postural sway asymmetries in patients with peripheral and central vestibular lesions, like those induced by galvanic or optokinetic stimulation in normal subjects, are not consequences of changes of the SPV.

Interaction of linear and angular vestibulo-ocular reflexes of human subjects in response to transient motion

The possibility of synergistic interaction between the canal and otolith components of the horizontal vestibulo-ocular reflex (VOR) was evaluated in human subjects by subtracting the response to pure angular rotation (AVOR) from the response to combined angular and translational motion (ALVOR) and comparing this difference with the VOR to isolated linear motion (LVOR). Assessments were made with target fixation at 60 cm and in darkness. Linear stimuli were acceleration steps attaining 0.25 g in less than 80 ms. To elicit responses to combined translational and angular head movements, the subjects were seated on a Barany chair with the head displaced forwards 40 cm from the axis of rotation. The chair was accelerated at approximately 300 deg/s2 to 127 deg/s peak angular velocity, the tangential acceleration of the head being comparable with that of isolated translation. Estimates of the contribution of smooth pursuit to responses in the light were made from comparisons of isolated pursuit of similar target trajectories. In the dark the slow phase eye movements evoked by combined canal-otolith stimuli were higher in magnitude by approximately a third than the sum of those produced by translation and rotation alone. In the light, the relative target displacement during isolated linear motion was similar to the difference in relative target displacements during eccentric and centred rotation. However, the gain of the translational component of compensatory eye movement during combined translational and angular motion was approximately unity, in contrast to the gain of the response to isolated linear motion, which was approximately a half. Pursuit performance was always poorer than target following during self-motion. The LVOR responses in the light were greater than the sum of the LVOR responses in the dark with pursuit eye movements. We conclude that, in response to transient motion, there is a synergistic enhancement of the translational VOR with concurrent canal stimulation and that the enhancement of the LVOR in the light is not due solely to pursuit.

Subjective postural vertical in peripheral and central vestibular disorders

The perception of subjective postural vertical was assessed in normals and patients with peripheral and central vestibular disorders and spasmodic torticollis. The subjects were seated in a motorized gimbal with the head and torso restrained and their eyes closed. The gimbal executed 7-10 cycles of tilt around the vertical at 1.5 degrees/s in either pitch or roll. Subjects indicated when they began to feel upright and again when they began to feel tilted by an analogous 3-position joystick. Normal subjects felt upright within a sector of 5-6 degrees around vertical in pitch and roll. Five patients with absent vestibular function, 25 torticollis patients and 3 patients with acute unilateral peripheral vestibular lesions showed a significant increase of the sector in pitch and roll, but only the latter had a mild directional bias. Two patients with long standing complete unilateral vestibular deficit and 8 patients with up or downbeat nystagmus in the vicinity of upright had abnormally large sectors within which they felt to be upright. The results suggest that vestibular function is important for the accurate perception of the postural vertical and that a directional asymmetry in vestibulo-ocular function or a head tilt does not necessarily correlate with a directional bias of subjective verticality.

[Comparison of the prognostic value between the nerve excitability test and maximum stimulation test in evaluation of Bell's palsy]

In the present comparative study we applied the nerve excitability test (NET) and the maximum stimulation test (MST) to 131 patients with idiopathic facial nerve palsy. Our aim was to determine their value in the evaluation of facial nerve function. Results showed that the percentage of error of the NET in the prognosis of facial nerve palsy was 16%. In contrast, the MST was simple in its application and had a high percentage of reliability (97%). However, it remains a qualitative method, since it is dependent on the examiner's observations.

Hearing loss and vestibular dysfunction in childhood from the use of streptomycin in Albania

With the entry of a large number of Albanians in the area of Epirus over the past 8 months, a significant number of children with hearing problems or deafness has been examined in the out patient ward of the University Hospital of Ioannina. From the Pediatric-Neurologic-Psychiatric and Otorhinolaryngologic examination of these children, 18 cases with hearing problems and vestibular dysfunction due to administration of streptomycin sulfate have been defined. This article reports the ototoxic drug which has been used and is still being used in Albania, the procedure of audiological and vestibular investigation, and the damage which has been evoked in the auditory and vestibular pathway of the children in whom it has been administered.

Sensitivity of external cuneate neurons to neck rotation in three-dimensional space

A functionally meaningful vestibular-neck interaction, such as it has been demonstrated for postural reflexes and self-motion perception, requires the spatial and temporal response characteristics of vestibular and neck signals to be similar. We investigated the spatial coding in neurons of the external cuneate nucleus (ECN) with natural neck and vestibular stimulations, and compared them to that of neurons in the descending and medial vestibular nuclei (DVN and MVN, respectively) obtained with vestibular stimulation. Neurons were recorded extracellularly in chronically prepared cats held under light barbiturate anesthesia. Neck stimulation was performed by sinusoidally rotating the animals' trunk relative to the earth-fixed head in six different vertical planes and in the horizontal plane. Vestibular stimulation was elicited by whole-body rotations in the corresponding planes. During neck stimulation in the vertical planes, most ECN neurons showed an approximately sinusoidal discharge modulation about resting rate, which became maximal during rotation in a specific plane. Off this plane, the response declined along a cosine function and reached zero in the orthogonal plane. The majority of these ECN neurons also responded to horizontal neck rotation; the resulting "optimal" direction of rotation in three-dimensional space varied considerably among the neurons. Yet, there was a certain preference; the majority of these ECN neurons fired maximally if trunk rotation in the yaw plane stretched the neck on the ipsilateral side, if roll brought the contralateral shoulder closer to the head, and if pitch brought the back closer to the occiput. A minority of ECN neurons showed more complex response patterns which could not be described by a single, optimal direction. About one third of the neck-sensitive ECN neurons tested showed weak responses during whole body rotation, which might stem from a weak vestibular input to this nucleus. In the DVN and MVN, the optimal direction in three-dimensional space with vestibular stimulation typically had a cosine-like spatial tuning. The spatial distribution of these directions clearly differed from that of neck-sensitive neurons in the ECN. We therefore assume that a further processing of the two input signals takes place at later stages in the CNS (e.g., in the vestibulo-cerebellum) in order to yield a functionally useful vestibular-neck interaction.

A multi-level intervention approach for care of HIV-positive haemophiliac and thalassaemic patients and their families

The experience gained from the application of an on-going multilevel intervention programme through an interdisciplinary team approach to the management of 30 HIV-positive children, adolescents and young people aged from 7 to 21 years (20 haemophiliac and 10 thalassaemic patients) and their families is described. The objective of the intervention was to assess the family's needs, to help parents and other family members to contain the anxiety of seropositive children and to improve their interraction with the family as well as with others in their social environment. The intervention was also designed to help family members to cope with their grief. Work with the medical and nursing staff, on the other hand, was intended to increase their understanding of the emotions caused in them by occupational stress, such as fear, anxiety, prejudice and feelings of guilt related to the iatrogenous nature of the infection. The need for follow-up studies is stressed to allow assessment of the effectiveness of the intervention and to search for protective factors, successful coping skills, strategies and adaptational resources.

Canal-neck interaction in vestibular nuclear neurons of the cat

The convergence and interaction of horizontal semicircular canal and neck proprioceptive inputs were studied in neurons of the caudal two thirds of the vestibular nuclear complex. Extracellular neuron activity was recorded under muscle relaxation and slight anesthesia in chronically prepared cats. The following stimulations were applied: horizontal rotations of (a) the whole body (labyrinth stimulation), (b) the trunk vs. the stationary head (neck stimulation), and (c) the head vs. the stationary trunk (combined labyrinth and neck stimulation). Of 152 neurons investigated, 83 (55%) showed convergence of the two inputs. In about half of these neurons, the neck input was very weak and hardly affected the labyrinthine response during head rotation. Judged from the response pattern, several of these neurons presumably were related to vestibulo-oculomotor function (i.e., vestibular nystagmus). In the other half (i.e., 27% of all neurons), sensitivity of the two inputs was similar. Both labyrinthine and neck responses contained a dynamic ("velocity") component; neck responses of more than half of these neurons had, in addition, a static ("position") component. The dynamic components were either "antagonistic" or "synergistic" as to their convergence during head rotation. When applying this combined stimulation, the dynamic components summed linearly, yielding subtration in case of antagonistic convergence and addition in case of synergistic convergence. In contrast, the static components of the neck responses remained largely unchanged during head rotation. However, the static head-to-trunk deflection determined the tonic discharge level in such neurons and thus facilitated or disfacilitated the dynamic responses to superimposed labyrinth stimulation. We suggest that the two patterns of labyrinthine neck interaction observed in vestibular nuclear neurons, i.e., subtration and addition, may be involved in the postural control of the trunk and head, respectively. In contrast, interference of the neck input with vestibulo-oculomotor function appears to be almost negligible in the intact cat.

Neuronal responses to horizontal neck deflection in the group X region of the cat's medullary brainstem

Neuronal responses to natural stimulation of neck proprioceptors were studied in the region of the small cell group x in the dorsolateral medullary brainstem of slightly anesthetized and paralyzed cats. Stimulation consisted of horizontal trunk rotations about C1 with the head fixed in space. Out of 74 neurons recorded, 92% showed an increase in discharge rate with ipsilateral neck stretch and a decrease with contralateral stretch (Type N I responses); 8% showed the reverse pattern (Type N II responses). In the primary head-to-trunk position, almost all neurons had tonic activity that probably stemmed from prestretched neck proprioceptors. Responses to sinusoidal stimulation and position trapezoids showed a static (position-sensitive) as well as a dynamic (essentially velocity-sensitive) component. The relative weight of the two components varied considerably among the neurons. It was not possible to distinguish discrete neuronal populations on the basis of the dynamic characteristics. There was no evidence of a convergent input from other receptor systems, such as the horizontal canal system. Several neurons responded to "muscle tapping" and showed an increase of the velocity component following systemic injection of succinylcholine. We take this as evidence that they may receive input from muscle spindle receptors.

Discrimination between trunk and head rotation; a study comparing neuronal data from the cat with human psychophysics

Kinesthetic information from labyrinthine and neck receptors is required for reflex control and conscious perception of posture and movement. This study considers (1) the neuronal responses to horizontal labyrinthine and neck stimulation and their interaction both in the anterior suprasylvian (AS) cortex and in the vestibular nuclei (VN) of cats, and (2) human turning sensation related to these stimuli. Convergence of labyrinthine (L) and neck (N) input of comparable sensitivity was found in 80% of the AS neurons and in only 27% of the VN neurons. At both sites, the on-direction of L-responses as well as N-responses was either to the ipsilateral or to the contralateral side (type I and type II responses, respectively). When combining the two stimuli during head rotation, the two inputs could be synergistic (same on-direction) or antagonistic (opposite on-directions). Their interaction consisted of either an additive or subtractive summation leading to enhanced or depressed interaction responses. These interaction patterns are compatible with the subtractive and additive mechanisms which have been proposed to be essential for the stabilisation of the trunk and of the head, respectively. The psychophysical experiments showed that human turning sensations depend on the part of the body to which they are referred. Subjects taking the trunk as reference, reported similar turning sensations during both labyrinthine and neck stimulation, and weak or no turning sensation during head rotation. This suggests an antagonistic interaction of the two inputs. In subjects taking the head as reference, neck stimulation induced an illusionary sensation of head turning. Its direction was such that it would be synergistic with the vestibularly induced sensation of head turning during isolated head rotation. Thus, there appear to exist parallels between the basic operations performed by neurons in cat and by human subjects during labyrinthine-neck interactions.