Different Purkinje cell pathologies cause specific patterns of progressive gait ataxia in mice.

Gait ataxia is one of the most common and impactful consequences of cerebellar dysfunction. Purkinje cells, the sole output neurons of the cerebellar cortex, are often involved in the underlying pathology, but their specific functions during locomotor control in health and disease remain obfuscated. We aimed to describe the effect of gradual adult-onset Purkinje cell degeneration on gaiting patterns in mice, and to determine whether two different mechanisms that both lead to Purkinje cell degeneration cause different patterns in the development of gait ataxia. Using the ErasmusLadder together with a newly developed limb detection algorithm and machine learning-based classification, we subjected mice to a challenging locomotor task with detailed analysis of single limb parameters, intralimb coordination and whole-body movement. We tested two Purkinje cell-specific mouse models, one involving stochastic cell death due to impaired DNA repair mechanisms (Pcp2-Ercc1-/-), the other carrying the mutation that causes spinocerebellar ataxia type 1 (Pcp2-ATXN1[82Q]). Both mouse models showed progressive gaiting deficits, but the sequence with which gaiting parameters deteriorated was different between mouse lines. Our longitudinal approach revealed that gradual loss of Purkinje cell function can lead to a complex pattern of loss of function over time, and that this pattern depends on the specifics of the pathological mechanisms involved. We hypothesize that this variability will also be present in disease progression in patients, and that our findings will facilitate the study of therapeutic interventions in mice, as subtle changes in locomotor abilities can be quantified by our methods.

Examination of the effects of coordination and balance problems on gait in ataxic multiple sclerosis patients.

OBJECTIVE: To investigate the effects of coordination and balance problems on gait and plantar pressure distribution in multiple sclerosis patients. METHODS: This was an observational, cross-sectional study. It was conducted at Necmettin Erbakan University between March and December 2017. Twenty-four individuals with coordination problems, 36 individuals with balance problems and 32 healthy individuals were included in the study. The EDSS, Functional Reach Test, Dynamic Gait Index, baropodometry and stabilometry evaluations were performed. RESULTS: There were significant differences between the groups (velocity p=0.000, cadence p=0.000, step width p=0.018, step length p=0.000, foot angle p=0.000). Multiple comparisons demonstrated that the velocities and cadences of the coordination group were lower, while their step widths were found to be higher, compared to the balance group (p=0.012, p=0.004, p=0.017, respectively). In static plantar pressure distribution, lateral forefoot pressure, lateral hindfoot pressure and medial hindfoot pressure were significantly different between the groups (p=0.002, p=0.000, respectively) Multiple comparisons showed that the pressure on the lateral part of the hindfoot in the coordination group was found to be significantly higher compared to the balance group (p=0.002). According to the dynamic plantar pressure distribution, lateral forefoot, medial forefoot, lateral hindfoot and medial hindfoot pressures were significantly different between the groups (p<0.05). CONCLUSION: Coordination and balance problems affect gait and plantar pressure distribution. The identification of these changes will help physiotherapists determine specific therapeutic targets.

Idiopathic very late-onset cerebellar ataxia: a Brazilian case series / Ataxia cerebellar idiopática com início muito tardio: uma série de casos brasileiros

ABSTRACTThe authors present a Brazilian case series of eight patients with idiopathic very-late onset (mean 75.5 years old) cerebellar ataxia, featuring predominantly gait ataxia, associated with cerebellar atrophy.Method: 26 adult patients with a diagnosis of idiopathic late onset cerebellar ataxia were analyzed in a Brazilian ataxia outpatient clinic and followed regularly over 20 years. Among them, 8 elderly patients were diagnosed as probable very late onset cerebellar ataxia. These patients were evaluated with neurological, ophthalmologic and Mini-Mental Status examinations, brain MRI, and EMG.Results: 62.5% of patients were males, mean age was 81.9 years-old, and mean age of onset was 75.5 years. Gait cerebellar ataxia was observed in all patients, as well as, cerebellar atrophy on brain MRI. Mild cognitive impairment and visual loss, due to macular degeneration, were observed in 50% of cases. Chorea was concomitantly found in 3 patients.Conclusion: We believe that this condition is similar the one described by Marie-Foix-Alajouanine presenting with mild dysarthria, associated with gait ataxia, and some patients had cognitive dysfunction and chorea.

RESUMOOs autores apresentam uma série de casos incluindo oito pacientes com ataxia cerebellar de início muito tardio (média de 75,5 anos de idade) apresentando ataxia de marcha, associada à atrofia cerebelar.Método: 26 pacientes adultos com diagnóstico de ataxia cerebelar de início tardio idiopática foram analisados ambulatorialmente e acompanhados regularmente ao longo de 20 anos. Destes, oito pacientes idosos foram diagnosticados como provável ataxia cerebelar início muito tardio. Os pacientes foram submetidos a um exame neurológico completo, avaliação cognitive e oftalmológica assim como ressonância magnética do cérebro e eletroneuromiografia tambem foram realizados.Resultados: 62,5% dos pacientes eram do sexo masculino, com idade média de 81,9 anos, com média de idade de início aos 75,5 anos. Ataxia cerebelar predominante de marcha foi observada em todos os pacientes, bem como, a atrofia cerebelar na ressonância magnética cerebral. Comprometimento cognitivo leve e perda visual, devido à degeneração macular, foram observados em 50% dos casos. Coréia foi encontrada em 3 pacientes.Conclusão: Acreditamos que esta condição é semelhante à descrita por Marie-Foix-Alajouanine apresentando disartria leve, associada a ataxia de marcha, disfunção cognitiva e coréia.

Idiopathic very late-onset cerebellar ataxia: a Brazilian case series.

UNLABELLED: The authors present a Brazilian case series of eight patients with idiopathic very-late onset (mean 75.5 years old) cerebellar ataxia, featuring predominantly gait ataxia, associated with cerebellar atrophy. METHOD: 26 adult patients with a diagnosis of idiopathic late onset cerebellar ataxia were analyzed in a Brazilian ataxia outpatient clinic and followed regularly over 20 years. Among them, 8 elderly patients were diagnosed as probable very late onset cerebellar ataxia. These patients were evaluated with neurological, ophthalmologic and Mini-Mental Status examinations, brain MRI, and EMG. RESULTS: 62.5% of patients were males, mean age was 81.9 years-old, and mean age of onset was 75.5 years. Gait cerebellar ataxia was observed in all patients, as well as, cerebellar atrophy on brain MRI. Mild cognitive impairment and visual loss, due to macular degeneration, were observed in 50% of cases. Chorea was concomitantly found in 3 patients. CONCLUSION: We believe that this condition is similar the one described by Marie-Foix-Alajouanine presenting with mild dysarthria, associated with gait ataxia, and some patients had cognitive dysfunction and chorea.

A quantitative framework for whole-body coordination reveals specific deficits in freely walking ataxic mice.

The coordination of movement across the body is a fundamental, yet poorly understood aspect of motor control. Mutant mice with cerebellar circuit defects exhibit characteristic impairments in locomotor coordination; however, the fundamental features of this gait ataxia have not been effectively isolated. Here we describe a novel system (LocoMouse) for analyzing limb, head, and tail kinematics of freely walking mice. Analysis of visibly ataxic Purkinje cell degeneration (pcd) mice reveals that while differences in the forward motion of individual paws are fully accounted for by changes in walking speed and body size, more complex 3D trajectories and, especially, inter-limb and whole-body coordination are specifically impaired. Moreover, the coordination deficits in pcd are consistent with a failure to predict and compensate for the consequences of movement across the body. These results isolate specific impairments in whole-body coordination in mice and provide a quantitative framework for understanding cerebellar contributions to coordinated locomotion.

Gait ataxia--specific cerebellar influences and their rehabilitation.

It is well known that the cerebellum is important for movement control and plays a critical role in balance and locomotion. As such, one of the most characteristic and sensitive signs of cerebellar damage is gait ataxia. However, characterizing ataxic gait is no easy task, because gait patterns are highly variable. This variability seems to result from the interaction of different factors, namely, (1) the primary motor deficits in balance control and multi-joint coordination and oculomotor dysfunction, (2) the safety strategies used, and (3) inaccurate adjustments in patients with loss of balance. In this report, we review different approaches to analyzing ataxic gait and studies to identify and quantify the different factors contributing to this movement disorder. We also discuss the influence of the cerebellum in adaptive locomotor control, the interaction between cognitive load and gait in dual-task paradigms, and the recent advances in rehabilitation of gait and posture for patients with cerebellar degeneration. In the second part, we discuss open questions concerning cerebellar mechanisms in multi-joint coordination during different walking conditions. Furthermore, we point out potential future directions in motor rehabilitation, with the objective of identifying predictors of rehabilitation outcome and the development of individualized training programs that potentially involve rehabilitation technology.

Effects of cerebellar lesions on working memory interacting with motor tasks of different complexities.

We examined the influence of focal cerebellar lesions on working memory (n-back task), gait, and the interaction between working memory and different gait tasks in a dual-task paradigm. The analysis included 17 young patients with chronic focal lesions after cerebellar tumor resection and 17 age-matched controls. Patients have shown mild to moderate ataxia. Lesion sites were examined on the basis of structural magnetic resonance imaging. N-back tasks were executed with different levels of difficulty (n = 1-4) during sitting (baseline), treadmill walking, and treadmill tandem walking (dual-task conditions). Patients exhibited decreased n-back performance particularly at difficult n-back levels and in dual-task conditions. Voxel-based lesion-symptom mapping revealed that decreased baseline n-back performance was associated with lesions of the posterolateral cerebellar hemisphere and the dentate nucleus. By contrast, decreased n-back performance in dual-task conditions was more associated with motor-related areas including dorsal portions of the dentate and the interposed nucleus, suggesting a prioritization of the motor task. During baseline walking, increased gait variability was associated with lesions in medial and intermediate regions, whereas for baseline tandem gait, lesions in the posterolateral hemispheres and the dentate nucleus became important. Posterolateral regions overlapped with regions related to baseline n-back performance. Consistently, we observed increased tandem gait variability with growing n-back difficulty in the dual-task condition. These findings suggest that dual-task effects in cerebellar patients are at least partially caused by a common involvement of posterolateral cerebellar regions in working memory and complex motor tasks.

Lamin B1 mediates cell-autonomous neuropathology in a leukodystrophy mouse model.

Adult-onset autosomal-dominant leukodystrophy (ADLD) is a progressive and fatal neurological disorder characterized by early autonomic dysfunction, cognitive impairment, pyramidal tract and cerebellar dysfunction, and white matter loss in the central nervous system. ADLD is caused by duplication of the LMNB1 gene, which results in increased lamin B1 transcripts and protein expression. How duplication of LMNB1 leads to myelin defects is unknown. To address this question, we developed a mouse model of ADLD that overexpresses lamin B1. These mice exhibited cognitive impairment and epilepsy, followed by age-dependent motor deficits. Selective overexpression of lamin B1 in oligodendrocytes also resulted in marked motor deficits and myelin defects, suggesting these deficits are cell autonomous. Proteomic and genome-wide transcriptome studies indicated that lamin B1 overexpression is associated with downregulation of proteolipid protein, a highly abundant myelin sheath component that was previously linked to another myelin-related disorder, Pelizaeus-Merzbacher disease. Furthermore, we found that lamin B1 overexpression leads to reduced occupancy of Yin Yang 1 transcription factor at the promoter region of proteolipid protein. These studies identify a mechanism by which lamin B1 overexpression mediates oligodendrocyte cell-autonomous neuropathology in ADLD and implicate lamin B1 as an important regulator of myelin formation and maintenance during aging.

White matter hyperintensities in Parkinson's disease: do they explain the disparity between the postural instability gait difficulty and tremor dominant subtypes?

BACKGROUND: Brain white matter hyperintensities (WMHs) commonly observed on brain imaging of older adults are associated with balance and gait impairment and have also been linked to cognitive deficits. Parkinson's disease (PD) is traditionally sub-classified into the postural instability gait difficulty (PIGD) sub-type, and the tremor dominant (TD) sub-type. Considering the known association between WMHs and axial symptoms like gait disturbances and postural instability, one can hypothesize that WMHs might contribute to the disparate clinical sub-types of patients with PD. METHODS: 110 patients with PD underwent a clinical evaluation and a 3T MRI exam. Based on the Unified Parkinson Disease Rating Scale, the patients were classified into motor sub-types, i.e., TD or PIGD, and scores reflecting PIGD and TD symptoms were computed. We compared white matter burden using three previously validated methods: one using a semi-quantitative visual rating scale in specific brain regions and two automated methods. RESULTS: Overall, MRI data were obtained in 104 patients. The mean WMHs scores and the percent of subjects with lesions in specific brain regions were similar in the two subtypes, p = 0.678. The PIGD and the TD scores did not differ even when comparing patients with a relatively high burden of WMHs to patients with a relatively low burden. Across most of the brain regions, mild to moderate correlations between WMHs and age were found (r = 0.23 to 0.41; p<0.021). Conversely, no significant correlations were found between WMHs and the PIGD score or disease duration. In addition, depressive symptoms and cerebro-vascular risk factors were similar among the two subtypes. CONCLUSIONS: In contrast to what has been reported previously among older adults, the present study could not demonstrate any association between WMHs and the PIGD or TD motor sub-types in patients with PD.

Characteristics of gait ataxia in δ2 glutamate receptor mutant mice, ho15J.

The cerebellum plays a fundamental, but as yet poorly understood, role in the control of locomotion. Recently, mice with gene mutations or knockouts have been used to investigate various aspects of cerebellar function with regard to locomotion. Although many of the mutant mice exhibit severe gait ataxia, kinematic analyses of limb movements have been performed in only a few cases. Here, we investigated locomotion in ho15J mice that have a mutation of the δ2 glutamate receptor. The cerebellum of ho15J mice shows a severe reduction in the number of parallel fiber-Purkinje synapses compared with wild-type mice. Analysis of hindlimb kinematics during treadmill locomotion showed abnormal hindlimb movements characterized by excessive toe elevation during the swing phase, and by severe hyperflexion of the ankles in ho15J mice. The great trochanter heights in ho15J mice were lower than in wild-type mice throughout the step cycle. However, there were no significant differences in various temporal parameters between ho15J and wild-type mice. We suggest that dysfunction of the cerebellar neuronal circuits underlies the observed characteristic kinematic abnormality of hindlimb movements during locomotion of ho15J mice.

Prefrontal cortex controls human balance during overground ataxic gait.

PURPOSE: 1) to verify if prefrontal cortex (PFC) is activated during over ground walking in ataxic patients, 2) to correlate the clinical parameters of gait with the PFC activation patterns. METHODS: Fourteen patients and 20 healthy subjects were studied. Ataxia was assessed by the Scale for the Assessment and Rating of Ataxia (SARA). A 2-channel near-infrared system was used to investigate the changes in oxygenated ([O2Hb]t) and deoxygenated ([HHb]t) hemoglobin concentrations on the PFC during gait. [O2Hb] baseline-corrected activation values ([O2Hb]c) were calculated by the difference between [O2Hb]t and [O2Hb] during upright posture ([O2Hb]b). RESULTS: [O2Hb]t was increased for both channels (respectively p < 0.01 and p = 0.01) only in the patients. No variation was observed in [HHB]t. The correlation coefficient between [O2Hb]c and the SARA gait score was respectively r: 0.878 (p < 0.01) and r: 0.839 (p < 0.01) for the right and left PFC, between [O2Hb]c and the SARA stance score respectively r: 0.893 (p < 0.01) and r: 0.832 (p < 0.01). CONCLUSIONS: During over ground gait PFC is bilaterally activated in patients with severe chronic ataxia. These findings may be associated with compensatory mechanisms which are involved in severe conditions when other nervous centers controlling balance are functionally not efficient.

Can loss of muscle spindle afferents explain the ataxic gait in Riley-Day syndrome?

The Riley-Day syndrome is the most common of the hereditary sensory and autonomic neuropathies (Type III). Among the well-recognized clinical features are reduced pain and temperature sensation, absent deep tendon reflexes and a progressively ataxic gait. To explain the latter we tested the hypothesis that muscle spindles, or their afferents, are absent in hereditary sensory and autonomic neuropathy III by attempting to record from muscle spindle afferents from a nerve supplying the leg in 10 patients. For comparison we also recorded muscle spindles from 15 healthy subjects and from two patients with hereditary sensory and autonomic neuropathy IV, who have profound sensory disturbances but no ataxia. Tungsten microelectrodes were inserted percutaneously into fascicles of the common peroneal nerve at the fibular head. Intraneural stimulation within muscle fascicles evoked twitches at normal stimulus currents (10-30 µA), and deep pain (which often referred) at high intensities (1 mA). Microneurographic recordings from muscle fascicles revealed a complete absence of spontaneously active muscle spindles in patients with hereditary sensory and autonomic neuropathy III; moreover, responses to passive muscle stretch could not be observed. Conversely, muscle spindles appeared normal in patients with hereditary sensory and autonomic neuropathy IV, with mean firing rates of spontaneously active endings being similar to those recorded from healthy controls. Intraneural stimulation within cutaneous fascicles evoked paraesthesiae in the fascicular innervation territory at normal stimulus intensities, but cutaneous pain was never reported during high-intensity stimulation in any of the patients. Microneurographic recordings from cutaneous fascicles revealed the presence of normal large-diameter cutaneous mechanoreceptors in hereditary sensory and autonomic neuropathy III. Our results suggest that the complete absence of functional muscle spindles in these patients explains their loss of deep tendon reflexes. Moreover, we suggest that their ataxic gait is sensory in origin, due to the loss of functional muscle spindles and hence a compromised sensorimotor control of locomotion.

Relationship of walking impairment and ankle-brachial index assessments with peripheral arterial translesional pressure gradients.

BACKGROUND: The relationship of peripheral arterial mean translesional pressure gradient (TLG) to presenting symptom, functional impairment, and initial noninvasive ABI assessments has never been established. OBJECTIVES: To evaluate the association between TLG, severity of walking impairment, rest and exercise ankle-brachial indices (ABI). METHODS: TLG in 19 patients presenting with claudication and single superficial femoral artery lesion were measured invasively. TLG was measured at rest and post-hyperemia induction with intra-arterial adenosine (100 and 200 µg), nitroglycerin (100 and 200 µg), and after 3 minutes of ipsilateral calf cuff pressure inflation-deflation sequence. For each patient, a walking impairment questionnaire (WIQ) was completed and rest and exercise ABI were measured prior to TLG assessment. RESULTS: Mean age was 60 ± 6 years, 89% were men. Mean WIQ score was 4817 ± 3549, mean rest and exercise ABI were 0.79 ± 0.14 and 0.59 ± 0.17, respectively, and mean exercise duration was 6.3 ± 3.4 minutes. TLG with 100 µg of adenosine strongly correlates with WIQ score (r = -0.723); rest ABI (r = -0.748); exercise ABI (r = -0.888), exercise duration (r = -0.711), and percent angiographic stenosis (r = -0.818), respectively (p < 0.01 for all). TLG with adenosine 200 µg, nitroglycerin 100 and 200 µg and after cuff inflation-deflation also demonstrated significant correlation. Receiver operator curve analysis demonstrated that a TLG > or = 11 mmHg post 100 µg adenosine administration had 71.43% sensitivity and 100% specificity for identifying patients with disease defining state of exercise ABI < or = 0.70. CONCLUSION: This study validates the utility of invasive TLG measurements using vasodilation for determining the functional and hemodynamic significance of superficial femoral artery lesions.

Dentatorubropallidoluysian atrophy without involuntary movement or dementia--a case report.

Recently, discussions about the clinical features of dentatorubropallidoluysian atrophy (DRPLA), especially the existence of an ataxo-choreoathetoid type, have increased. Traditionally, DRPLA patients have been thought to present with involuntary movements and dementia. Here, we report a patient that presented with ataxia, spasticity of the right lower extremity and mild sensory disturbances. He did not show either apparent involuntary movement or dementia. Mini-mental state examination demonstrated a score of 29/30. The cerebellar output system involving the dentate nuclei and superior cerebellar peduncles seemed to be atrophic yet the cerebellar input system involving the middle cerebellar peduncles was preserved on MRI. In addition, there was an expansion of the atrophin1 (ATN1) CAG repeat of chromosome 12p: 9/61. This seems to be the first case report of a genetically confirmed DRPLA patient presenting with clinical manifestations of Machado-Joseph disease (MJD/SCA3).

[Rupture of the extensor carpi radialis tendon in two horses]. / Ruptur der Sehne des Musculus extensor carpi radialis bei zwei Pferden.

Symptoms, diagnosis, therapy and clinical outcome of 2 horses which acquired a complete rupture of the extensor carpi radialis tendon by accident are described. The resulting gait abnormalities are very typical, so that the problem can be diagnosed already by clinical examination. With the help of ultrasound the diagnosis could be confirmed and the degree of damage quantified. The open wounds in the carpal region were surgically treated in a standing position and the limbs of both horses were kept under a splint bandage for 6 to 8 weeks. Prognosis in these cases was good, as both horses returned within 6 months back to their previous work.

Pontocerebellar volume deficits and ataxia in alcoholic men and women: no evidence for "telescoping".

INTRODUCTION: Brain volume shrinkage is common in treatment-seeking patients with alcohol use disorders. Whether women are more vulnerable to brain dysmorphology than men despite lower alcohol consumption levels or shorter dependency ("telescoping effect") remains controversial and has not been considered with respect to infratentorial structures or their potential contribution to ataxia. METHODS: The 200 participants included 64 men and 31 women with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition alcohol dependence and 105 controls. An infratentorial region (pons, cerebellar hemispheres, vermis (anterior, posterior, and inferior sectors), fissures, cisterns, fourth ventricle) was quantified with atlas-based parcellation. To enable comparison of men and women, regional tissue volumes were expressed as ratios of tissue in the volume. Participants also completed quantitative ataxia testing. RESULTS: Total infratentorial and vermian tissue ratios were significantly smaller in alcoholics than controls; alcoholic women did not show disproportionately greater volume deficits than alcoholic men. A re-analysis including alcoholic men and women matched in alcohol consumption, onset age, abstinence duration, and age revealed again that alcoholic women did not have disproportionately greater regional vermian volume deficits than alcoholic men. Alcoholic men and women were impaired in all measures of ataxia, which correlated with low infratentorial tissue ratios in men. DISCUSSION: Alcoholic men showed deficits of pontocerebellar volume ratios, yet alcoholic women did not display signs of "telescoping". Further, alcoholic men and women both showed signs of ataxia of gait and balance, related to affected pontocerebellar systems in the men but not the women, suggesting the need to consider other neural substrates for ataxia in women.

Rescue of motor coordination by Purkinje cell-targeted restoration of Kv3.3 channels in Kcnc3-null mice requires Kcnc1.

The role of cerebellar Kv3.1 and Kv3.3 channels in motor coordination was examined with an emphasis on the deep cerebellar nuclei (DCN). Kv3 channel subunits encoded by Kcnc genes are distinguished by rapid activation and deactivation kinetics that support high-frequency, narrow action potential firing. Previously we reported that increased lateral deviation while ambulating and slips while traversing a narrow beam of ataxic Kcnc3-null mice were corrected by restoration of Kv3.3 channels specifically to Purkinje cells, whereas Kcnc3-mutant mice additionally lacking one Kcnc1 allele were partially rescued. Here, we report mice lacking all Kcnc1 and Kcnc3 alleles exhibit no such rescue. For Purkinje cell output to reach the rest of the brain it must be conveyed by neurons of the DCN or vestibular nuclei. As Kcnc1, but not Kcnc3, alleles are lost, mutant mice exhibit increasing gait ataxia accompanied by spike broadening and deceleration in DCN neurons, suggesting the facet of coordination rescued by Purkinje-cell-restricted Kv3.3 restoration in mice lacking just Kcnc3 is hypermetria, while gait ataxia emerges when additionally Kcnc1 alleles are lost. Thus, fast repolarization in Purkinje cells appears important for normal movement velocity, whereas DCN neurons are a prime candidate locus where fast repolarization is necessary for normal gait patterning.