Muscle Tone Physiology and Abnormalities

The simple definition of tone as the resistance to passive stretch is physiologically a complex interlaced network encompassing neural circuits in the brain, spinal cord, and muscle spindle. Disorders of muscle tone can arise from dysfunction in these pathways and manifest as hypertonia or hypotonia. The loss of supraspinal control mechanisms gives rise to hypertonia, resulting in spasticity or rigidity. On the other hand, dystonia and paratonia also manifest as abnormalities of muscle tone, but arise more due to the network dysfunction between the basal ganglia and the thalamo-cerebello-cortical connections. In this review, we have discussed the normal homeostatic mechanisms maintaining tone and the pathophysiology of spasticity and rigidity with its anatomical correlates. Thereafter, we have also highlighted the phenomenon of network dysfunction, cortical disinhibition, and neuroplastic alterations giving rise to dystonia and paratonia.

Quantitative Measurement of Rigidity in Parkinson´s Disease: A Systematic Review

Rigidity is one of the cardinal symptoms of Parkinson´s disease (PD). Present in up 89% of cases, it is typically assessed with clinical scales. However, these instruments show limitations due to their subjectivity and poor intra- and inter-rater reliability. To compile all of the objective quantitative methods used to assess rigidity in PD and to study their validity and reliability, a systematic review was conducted using the Web of Science, PubMed, and Scopus databases. Studies from January 1975 to June 2019 were included, all of which were written in English. The Strengthening the Reporting of observational studies in Epidemiology Statement (STROBE) checklist for observational studies was used to assess the methodological rigor of the included studies. Thirty-six studies were included. Rigidity was quantitatively assessed in three ways, using servomotors, inertial sensors, and biomechanical and neurophysiological study of muscles. All methods showed good validity and reliability, good correlation with clinical scales, and were useful for detecting rigidity and studying its evolution. People with PD exhibit higher values in terms of objective muscle stiffness than healthy controls. Rigidity depends on the angular velocity and articular amplitude of the mobilization applied. There are objective, valid, and reliable methods that can be used to quantitatively assess rigidity in people with PD.

Electrophysiological resting state networks of predominantly akinetic-rigid Parkinson patients: Effects of dopamine therapy

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Analysis of whole-brain frequency-specific resting state networks with EEG.

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Comparison of dopamine medication ON and OFF state in Parkinson patients.

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Parkinson patients show distinct frequency-specific network alterations.

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Motor network at beta frequencies is re-instated after dopamine medication.

Parkinson's disease (PD) causes both motor and non-motor symptoms, which can partially be reversed by dopamine therapy. These symptoms as well as the effect of dopamine may be explained by distinct alterations in whole-brain architecture. We used functional connectivity (FC) and in particular resting state network (RSN) analysis to identify such whole-brain alterations in a frequency-specific manner. In addition, we hypothesized that standard dopaminergic medication would have a normalizing effect on these whole brain alterations. We recorded resting-state EEGs of 19 PD patients in the medical OFF and ON states, and of 12 healthy age-matched controls. The PD patients were either of akinetic-rigid or mixed subtype. We extracted RSNs with independent component analysis in the source space for five frequency bands. Within the sensorimotor network (SMN) the supplementary motor area (SMA) showed decreased FC in the OFF state compared to healthy controls. This finding was reversed after dopamine administration. Furthermore, in the OFF state no stable SMN beta component could be identified. The default mode network showed alterations due to PD independent of the medication state. The visual network was altered in the OFF state, and reinstated to a pattern similar to healthy controls by medication. In conclusion, PD causes distinct RSN alterations, which are partly reversed after levodopa administration. The changes within the SMN are of particular interest, because they broaden the pathophysiological understanding of PD. Our results identify the SMA as a central network hub affected in PD and a crucial effector of dopamine therapy.

Management of Dysphagia in Patients with Parkinson's Disease and Related Disorders

Various methods of rehabilitation for dysphagia have been suggested through the experience of treating stroke patients. Although most of these patients recover their swallowing function in a short period, dysphagia in Parkinson's disease (PD) and Parkinson-related disorder (PRD) degenerates with disease progression. Muscle rigidity and bradykinesia are recognized as causes of swallowing dysfunction, and it is difficult to easily apply the strategies for stroke to the rehabilitation of dysphagia in PD patients. Disease severity, weight loss, drooling, and dementia are important clinical predictors. Silent aspiration is a pathognomonic sign that may lead to aspiration pneumonia. Severe PD patients need routine video fluoroscopy or video endoscopy to adjust their food and liquid consistency. Patients with PRD experience rapid progression of swallowing dysfunction. Nutrition combined with nasogastric tube feeding or percutaneous endoscopic gastrostomy feeding should be considered owing to the increased risk of aspiration and difficulty administrating oral nutrition.

Stiff limb syndrome with lower limb myoclonus: A case report

RATIONALE

stiff limb syndrome (SLS) is a variant of stiff-man syndrome, primarily affecting a specific limb. Its diagnosis has always been challenging due to the lack of a specific confirmation test. We present a rare case of a patient with lower limb myoclonus and rigidity.

PATIENT CONCERNS

A 53-year-old male presented with a sudden onset of progressive left lower extremity myoclonus and muscle rigidity for 3 days. He rapidly showed signs of right lower limb involvement with severe joint stiffness and inability to walk.

DIAGNOSIS

The symptoms nature, physical examination, careful elimination of differential diagnosis suggested a diagnosis of stiff limb syndrome.

INTERVENTIONS

Intravenous infusion of gamma globulin 0.4 mg/kg coupled with baclofen and clonazepam were given after admission. He also received an injection of botulinum toxin A to relieve his muscle stiffness.

OUTCOMES

The patients' condition improved after the initial treatment with complete disappearance of muscle twitching. Further improvements were seen later on after the local administration of botulinum toxin A.

LESSONS

Stiff limb syndrome shares the same complex symptoms with many other conditions. Its diagnosis relies heavily on clinical presentations and on ruling out other conditions. However, unusual symptoms such as myoclonus can occur in few cases and together with the rarity of the condition, the prevalence of misdiagnosis is high. Therefore, being aware and recognizing the signs and symptoms is crucial for proper management. Additionally, EMG is a very important test if the present condition is suspected. However, a negative EMG result or a negative anti-glutamic acid decarboxylase antibody test should not exclude SLS diagnosis.

Washout of chronic therapeutic deep brain stimulation increases cortical phase-amplitude coupling

Invasive human brain recordings have shown that acute therapeutic deep brain stimulation (DBS) reduces cortical synchronization, measured by coupling of beta phase to gamma amplitude. Here we show by noninvasive scalp electroencephalography that withdrawal of chronic DBS elevates phase-amplitude coupling, in proportion to the worsening of contralateral rigidity.

The long-term efficacy of STN vs GPi deep brain stimulation for Parkinson disease: A meta-analysis

OBJECTIVE

This meta-analysis assessed the long-term efficacy of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus interna (GPi) for Parkinson disease (PD).

METHODS

PubMed, Cochrane Library, and Clinical Trials databases were searched. Outcomes were unified Parkinson disease rating scale section (UPDRS) III off-medication score, Parkinson's disease questionnaire: 39 activities of daily living (PDQ-39 ADL) score, and levodopa-equivalent dosage after DBS.

RESULTS

During the off-medication state, pooled weighted mean difference (WMD) of UPDRS III score was .69 (95% confidence interval [CI] = -1.77 to 3.16, P = .58). In subgroup analysis, WMD of UPDRS III off-medication scores from baseline to 2 years and 3 years post-DBS were -.61 (95% CI = -2.97 to 1.75, P = .61) and 2.59 (95% CI = -2.30 to 7.47, P = .30). Pooled WMD of changes in tremor, rigidity, and gait scores were 1.12 (95% CI = -0.05 to 2.28, P = .06), 1.22 (95% CI = -0.51 to 2.94, P = .17) and .37 (95% CI = -0.13 to 0.87, P = .15), respectively. After DBS, pooled WMD of PDQ-39 ADL and LED were -3.36 (95% CI = -6.36 to -0.36, P = .03) and 194.89 (95% CI = 113.16 to 276.63, P < .001).

CONCLUSIONS

STN-DBS and GPi-DBS improve motor function and activities of daily living for PD. Differences in the long-term efficacy for PD on motor symptoms were not observed.

Muscular MRI-based algorithm to differentiate inherited myopathies presenting with spinal rigidity

OBJECTIVES

Inherited myopathies are major causes of muscle atrophy and are often characterized by rigid spine syndrome, a clinical feature designating patients with early spinal contractures. We aim to present a decision algorithm based on muscular whole body magnetic resonance imaging (mWB-MRI) as a unique tool to orientate the diagnosis of each inherited myopathy long before the genetically confirmed diagnosis.

METHODS

This multicentre retrospective study enrolled 79 patients from referral centres in France, Brazil and Chile. The patients underwent 1.5-T or 3-T mWB-MRI. The protocol comprised STIR and T1 sequences in axial and coronal planes, from head to toe. All images were analyzed manually by multiple raters. Fatty muscle replacement was evaluated on mWB-MRI using both the Mercuri scale and statistical comparison based on the percentage of affected muscle.

RESULTS

Between February 2005 and December 2015, 76 patients with genetically confirmed inherited myopathy were included. They were affected by Pompe disease or harbored mutations in RYR1, Collagen VI, LMNA, SEPN1, LAMA2 and MYH7 genes. Each myopathy had a specific pattern of affected muscles recognizable on mWB-MRI. This allowed us to create a novel decision algorithm for patients with rigid spine syndrome by segregating these signs. This algorithm was validated by five external evaluators on a cohort of seven patients with a diagnostic accuracy of 94.3% compared with the genetic diagnosis.

CONCLUSION

We provide a novel decision algorithm based on muscle fat replacement graded on mWB-MRI that allows diagnosis and differentiation of inherited myopathies presenting with spinal rigidity.

KEY POINTS

• Inherited myopathies are rare, diagnosis is challenging and genetic tests require specialized centres and often take years. • Inherited myopathies are often characterized by spinal rigidity. • Whole body magnetic resonance imaging is a unique tool to orientate the diagnosis of each inherited myopathy presenting with spinal rigidity. • Each inherited myopathy in this study has a specific pattern of affected muscles that orientate diagnosis. • A novel MRI-based algorithm, usable by every radiologist, can help the early diagnosis of these myopathies.

The effect of subthalamic stimulation on viscoelastic stiffness of skeletal muscles in patients with Parkinson's disease

BACKGROUND

Myotonometric evaluation of viscoelastic stiffness of skeletal muscles has been proposed to document the effect of surgical or pharmacological treatment on rigidity in patients with Parkinson's disease. The aim of the study was to analyze the changes of viscoelastic stiffness induced by deep brain stimulation.

METHODS

Fifteen patients in an advanced stage of Parkinson's disease participated in the study. The study took place in the off-medication conditions after one night of drug withdrawal. The Unified Parkinson's Disease Rating Scale was used for clinical assessment of the disease. Myotonometry was used to measure viscoelastic stiffness in the resting muscles before and directly after passive wrist movements, commonly used for clinical evaluation of rigidity. The measurements were repeated during the stimulation-on and stimulation-off periods and compared with fifteen healthy control persons.

FINDINGS

The clinical scores for wrist rigidity improved from 3.0 (1-4) to 0.93 (0-2) (P<0.05) due to brain stimulation. The mean values of viscoelastic stiffness were similar before and after passive wrist movements, but the differences between the patients with high vs. low rigidity values (354.9 vs 310.2N/m; P<0.05) and in stimulation-off vs. stimulation-on conditions (342.7 vs 310.5N/m; P<0.05) were significant only if the measurements had been performed after passive wrist movements.

INTERPRETATION

Effective deep brain stimulation and increased rigidity can significantly change viscoelastic stiffness in the resting muscles in patients with Parkinson's disease, especially if evaluated after passive wrist movements. This paper supports the use of myotonometry for objective quantification of parkinsonian rigidity at rest.

The Motor Syndrome of Parkinson's Disease

The clinical diagnosis of Parkinson's disease (PD) is centered on a specific motor syndrome that is characterized by the presence of bradykinesia, plus rest tremor, muscle rigidity, or both. Recently, novel criteria for diagnosing PD have been released that rehearse the motor syndrome as the core feature of PD. Beyond these three main symptoms, other motor features might be present in PD including gait difficulties and postural instability. Moreover, patients with PD usually develop motor complications 5-10 years into their disease. These motor complications are the strongest predictor of PD pathology and are in fact used clinically to support the diagnosis. Ancillary investigations are usually of little utility and to perform only in selected cases, which remarks the importance of the clinical examination for making the diagnosis of PD or suspect other condition that can be masquerading it.

Early-onset Parkinson's Disease Associated with Chromosome 22q11.2 Deletion Syndrome

We herein report the case of a 43-year-old man with a 4-year history of resting tremor and akinesia. His resting tremor and rigidity were more prominent on the left side. He also presented retropulsion. His symptoms responded to the administration of levodopa. The patient also had a cleft lip and palate, cavum vergae, and hypoparathyroidism. A chromosome analysis disclosed a hemizygous deletion in 22q11.2, and he was diagnosed with early-onset Parkinson's disease associated with 22q11.2 deletion syndrome. However, the patient lacked autonomic nerve dysfunction, and his cardiac uptake of (123)I-metaiodobenzylguanidine was normal, indicating an underlying pathological mechanism that differed to that of sporadic Parkinson's disease.

Lethal neonatal rigidity and multifocal seizure syndrome--report of another family with a BRAT1 mutation

We describe two siblings born to consanguineous Arab-Muslim parents who presented in early infancy with myoclonic seizures, hypertonia and contractures, arrested head growth, inability to swallow, and bouts of apnea-bradycardia, culminating in cardiac arrest and death. Whole-genome sequencing yielded a c.1173delG mutation in the BRAT1 gene. Three recent reports identified mutations in the same gene in three infants from three Amish sibships, one Mexican neonate and two Japanese siblings with similar clinical manifestations. The authors speculated that the destabilization of the encoded protein may underlie the catastrophic epilepsy and corticobasal neuronal degeneration. We suggest that BRAT1 be added to the growing list of genes that are related to severe early infantile (neonatal) epileptic encephalopathy.

[Correlation between cognitive impairment and postural instability in patients with Parkinson's disease]

Correlation between frontal-executive function and motor functions, such as gait and postural control, has attracted attention in Parkinson's disease (PD). However, correlations between other cognitive functional domains and motor functions have not been examined. Thus, we examined the correlation between different domains of cognitive function and motor functions. Sixty-five PD patients were recruited for the present study. Cognitive functions were assessed by the 10 subtests of the Neurobehavioral Cognitive Status Examination (COGNISTAT). Motor functions were assessed by the Unified Parkinson's Disease Rating Scale (UPDRS) as partIII for general motor function and sum of related items for tremor, rigidity, bradykinesia, and postural instability. Spearman's correlation coefficients between each cognitive and motor assessment were compared. Among the 10 subtests of the COGNISTAT, constructions showed significant correlation with UPDRS partIII (p<0.01), bradykinesia (p<0.01), and postural instability (p<0.001). The latter correlation was stronger than those between all motor assessments and both all patients backgrounds and other COGNISTAT subtests. In PD patients, postural instability correlates with not only frontal executive dysfunctions but also parietal dysfunctions, such as visuospatial and constructive impairments. The postural maintenance system is suggested to share common physiology with not only frontal-executive function but also parietal functions.

Stiffness is more than just duration and severity: a qualitative exploration in people with rheumatoid arthritis

OBJECTIVE

Stiffness is internationally recognized as an important indicator of inflammatory activity in RA but is poorly understood and difficult to measure. The aim of this study was to explore the experience of stiffness from the patient perspective.

METHODS

Semi-structured interviews conducted with 16 RA patients were analysed independently by researchers and pat.ient partners using inductive thematic analysis.

RESULTS

Six themes were identified. Part of having RA identified stiffness as a normal consequence of RA, perceived as associated with disease-related aspects such as fluctuating disease activity, other RA symptoms and disease duration. Local and widespread highlighted stiffness occurring not only in joints, but also over the whole body, being more widespread during the morning or flare. Linked to behaviour and environment illustrated factors that influence stiffness, including movement, medications and weather. Highly variable captured the fluctuating nature of stiffness within and between patients and in relation to temporality, duration and intensity. Impacts on daily life emphasized the effect of stiffness on a range of domains, including physical function, quality of life, psychological well-being, activities of daily living and participation in work and leisure activities. Requires self-management detailed self-management strategies targeting both the symptom and its consequences.

CONCLUSION

Patients' experiences of stiffness were varied, complex and not exclusive to the morning period. Importantly, stiffness was reported in terms of impact rather than the traditional measurement concepts of severity or duration. Based on these findings, further research is needed to develop a patient-centred measure that adequately reflects inflammatory activity.

Parkinsonian features in hereditary diffuse leukoencephalopathy with spheroids (HDLS) and CSF1R mutations

Atypical Parkinsonism associated with white matter pathology has been described in cerebrovascular diseases, mitochondrial cytopathies, osmotic demyelinating disorders, leukoencephalopathies leukodystrophies, and others. Hereditary diffuse leukoencephalopathy with spheroids (HDLS) is an autosomal dominant disorder with symptomatic onset in midlife and death within a few years after symptom onset. Neuroimaging reveals cerebral white matter lesions that are pathologically characterized by non-inflammatory myelin loss, reactive astrocytosis, and axonal spheroids. Most cases are caused by mutations in the colony-stimulating factor 1 receptor (CSF1R) gene. We studied neuropathologically verified HDLS patients with CSF1R mutations to assess parkinsonian features. Ten families were evaluated with 16 affected individuals. During the course of the illness, all patients had at least some degree of bradykinesia. Fifteen patients had postural instability, and seven had rigidity. Two patients initially presented with parkinsonian gait and asymmetrical bradykinesia. These two patients and two others exhibited bradykinesia, rigidity, postural instability, and tremor (two with resting) early in the course of the illness. Levodopa/carbidopa therapy in these four patients provided no benefit, and the remaining 12 patients were not treated. The mean age of onset for all patients was about 45 years (range, 18-71) and the mean disease duration was approximately six years (range, 3-11). We also reviewed HDLS patients published prior to the CSF1R discovery for the presence of parkinsonian features. Out of 50 patients, 37 had gait impairments, 8 rigidity, 7 bradykinesia, and 5 resting tremor. Our report emphasizes the presence of atypical Parkinsonism in HDLS due to CSF1R mutations.

β Subunit M2-M3 loop conformational changes are uncoupled from α1 β glycine receptor channel gating: implications for human hereditary hyperekplexia

Hereditary hyperekplexia, or startle disease, is a neuromotor disorder caused mainly by mutations that either prevent the surface expression of, or modify the function of, the human heteromeric α1 β glycine receptor (GlyR) chloride channel. There is as yet no explanation as to why hyperekplexia mutations that modify channel function are almost exclusively located in the α1 to the exclusion of β subunit. The majority of these mutations are identified in the M2–M3 loop of the α1 subunit. Here we demonstrate that α1 β GlyR channel function is less sensitive to hyperekplexia-mimicking mutations introduced into the M2–M3 loop of the β than into the α1 subunit. This suggests that the M2–M3 loop of the α subunit dominates the β subunit in gating the α1 β GlyR channel. A further attempt to determine the possible mechanism underlying this phenomenon by using the voltage-clamp fluorometry technique revealed that agonist-induced conformational changes in the β subunit M2–M3 loop were uncoupled from α1 β GlyR channel gating. This is in contrast to the α subunit, where the M2–M3 loop conformational changes were shown to be directly coupled to α1 β GlyR channel gating. Finally, based on analysis of α1 β chimeric receptors, we demonstrate that the structural components responsible for this are distributed throughout the β subunit, implying that the β subunit has evolved without the functional constraint of a normal gating pathway within it. Our study provides a possible explanation of why hereditary hyperekplexia-causing mutations that modify α1 β GlyR channel function are almost exclusively located in the α1 to the exclusion of the β subunit.

Differential involvement of striato- and cerebello-thalamo-cortical pathways in tremor- and akinetic/rigid-predominant Parkinson's disease

Parkinson's disease (PD) presents clinically with varying degrees of resting tremor, rigidity, and bradykinesia. For decades, striatal-thalamo-cortical (STC) dysfunction has been implied in bradykinesia and rigidity, but does not explain resting tremor in PD. To understand the roles of cerebello-thalamo-cortical (CTC) and STC circuits in the pathophysiology of the heterogeneous clinical presentation of PD, we collected functional magnetic resonance imaging (fMRI) data from 17 right-handed PD patients [nine tremor predominant (PDT) and eight akinetic-rigidity predominant (PDAR)] and 14 right-handed controls while they performed internally-guided (IG) sequential finger tapping tasks. The percentage of voxels activated in regions constituting the STC and CTC [divided as cerebellar hemisphere-thalamo-cortical (CHTC) and vermis-thalamo-cortical (CVTC)] circuits was calculated. Multivariate analysis of variance compared the activation patterns of these circuits between study groups. Compared to controls, both PDAR and PDT subjects displayed an overall increase in the percentage of voxels activated in both STC and CTC circuits. These increases reached statistical significance in contralateral STC and CTC circuits for PDT subjects, and in contralateral CTC pathways for PDAR subjects. Comparison of PDAR and PDT subjects revealed significant differences in ipsilateral STC (P=0.005) and CTC (P=0.043 for CHTC and P=0.003 for CVTC) circuits. These data support the differential involvement of STC and CTC circuits in PD subtypes, and help explain the heterogeneous presentation of PD symptoms. These findings underscore the importance of integrating CTC circuits in understanding PD and other disorders of the basal ganglia.

Neurotoxic manifestations of an overdose intrathecal injection of gadopentetate dimeglumine

The intravenous administration of gadopentetate dimeglumine (GD) is relatively safe and rarely causes systemic toxicity in the course of routine imaging studies. However, the general safety of intrathecal GD has not been established. We report a very rare case of an overdose intrathecal GD injection presenting with neurotoxic manifestations, including a decreased level of consciousness, global aphasia, rigidity, and visual disturbance.

Pseudomeningeal syndrome of Dupre associated with cervical discopathy--case report

BACKGROUND AND PURPOSE

The below publication presents a case of a 51-year-old patient with cervical discopathy of unusual clinical course.

CASE REPORT

The symptoms of the disease suddenly became aggravated and took a form of meningeal syndrome without inflammation of cerebrospinal fluid. The authors emphasize the symptomatology and diagnostic difficulties connected to unusual clinical course of cervical discopathy at the level of VC3/VC4.

DISCUSSION

Both medical and neurosurgical approaches to clinical history of cervical discopathic patient were presented in details. The patient underwent anterior cervical interbody fusion and the operative procedure was very effective for a few years up till now.

A modular planar robotic manipulandum with end-point torque control

Robotic manipulanda are extensively used in investigation of the motor control of human arm movements. They permit the application of translational forces to the arm based on its state and can be used to probe issues ranging from mechanisms of neural control to biomechanics. However, most current designs are optimized for studying either motor learning or stiffness. Even fewer include end-point torque control which is important for the simulation of objects and the study of tool use. Here we describe a modular, general purpose, two-dimensional planar manipulandum (vBOT) primarily optimized for dynamic learning paradigms. It employs a carbon fibre arm arranged as a parallelogram which is driven by motors via timing pulleys. The design minimizes the intrinsic dynamics of the manipulandum without active compensation. A novel variant of the design (WristBOT) can apply torques at the handle using an add-on cable drive mechanism. In a second variant (StiffBOT) a more rigid arm can be substituted and zero backlash belts can be used, making the StiffBOT more suitable for the study of stiffness. The three variants can be used with custom built display rigs, mounting, and air tables. We investigated the performance of the vBOT and its variants in terms of effective end-point mass, viscosity and stiffness. Finally we present an object manipulation task using the WristBOT. This demonstrates that subjects can perceive the orientation of the principal axis of an object based on haptic feedback arising from its rotational dynamics.

[Subacute worsening of rigidity in a patient with Parkinson disease]

In this paper we report a patient with Parkinson's disease (PD) presenting with subacute motor symptoms, especially rigidity. The 75-year-old man had relatively moderate PD for 12 years, which was treated with levodopa until he developed marked rigidity. The rigidity became worse, with prolonged off-periods, despite treatment with increased doses of levodopa. At the time of hospitalization he was unable to walk independently, but the clinical neurological examination only revealed aggravation of parkinsonian signs. MRI of the brain showed an intracerebral lesion, which was later confirmed as glioblastoma multiforme. The main feature was onset of marked rigidity a few weeks before severe tumour-specific symptoms developed, but spasticity or hyperreflexia were neither reported at the time of symptom exacerbation nor during hospitalization. This case demonstrates the importance of considering other underlying neurological disease in parkinsonian patients presenting with rapid progression of parkinsonian symptoms.

[Stiff-person syndrome: a case report]

INTRODUCTION

Stiff-person (stiff-man) syndrome is characterised by symptoms of muscular rigidity and spasms, which are generally of an axial nature. Involuntary contractions of the agonist and antagonist muscles caused by activity of the motor units during rest are the main clinical and electrophysiological marker of the disease. The nature of the syndrome is considered to be autoimmune, with positive glutamic acid decarboxylase (anti-GAD) antibodies in most patients. These antibodies exert an influence over GABAergic transmission.

CASE REPORT

A 29-year-old female who was admitted to hospital with a diagnosis of psychogenic mutism. While in hospital the patient developed a clinical picture consisting in generalised stiffness that was predominantly axial and proximal with hyperreflexia in the four limbs and strong contraction of the muscles of the abdomen. The most striking lab finding was the presence of anti-GAD, anti-parietal cells, anti-microsomal/TPO and antithyroglobulin antibodies, together with oligoclonal immunoglobulin G bands in the cerebrospinal fluid. Treatment was established with benzodiazepines, antispastic agents and corticosteroids, and the clinical symptoms progressively improved until they had partially remitted at two months. The lab findings and clinical features are compatible with stiff-person syndrome in a patient with associated psychiatric comorbidity.

CONCLUSIONS

Anti-GAD antibodies are not exclusive to stiff-person syndrome and can also be found in a number of other autoimmune disorders. Other mechanisms which can also produce a dysfunction of the GABAergic system have also been suggested. The syndrome can be difficult to diagnose from the clinical point of view and it must therefore be borne in mind in patients who begin with unexplainable stiffness and spasms because it is a potentially treatable pathology.

Tasks of attention augment rigidity in mild Parkinson disease

OBJECTIVE

The purpose of this study was to determine whether tasks involving effortful attention would cause augmentation of rigidity in patients with mild Parkinson disease.

METHODS

In 17 subjects with mild Parkinson disease, rigidity in a single arm was assessed during various experimental conditions by a blinded movement disorders neurologist. Rigidity was scored separately at the wrist and the elbow using an ordinal scale. In three of the conditions, sustained attention was directed toward visual, auditory or movement-related stimuli. Two varieties of Froment maneuver served as positive controls: contralateral hand opening-closing or ipsilateral foot tapping. In addition, rigidity was assessed twice with subjects resting. The examiner was unaware of the sequence of experimental conditions and this was changed for each subject. Mean rigidity scores for the various experimental conditions were compared against the baseline state (an average of both trials with the patient resting) using a repeated measures ANOVA and post-hoc Tukey-Kramer multiple comparisons test.

RESULTS

Rigidity was significantly increased from baseline with each of the attentional tasks (p < 0.01 to p < 0.001) and also with the two Froment maneuvers (p < 0.001). Rigidity augmentation with contralateral hand opening-closing was significantly greater than with any of the attentional tasks (p < 0.05 to p < 0.001).

CONCLUSION

Tasks of effortful attention did appear to augment rigidity in patients with mild Parkinson disease. We speculate that the greater augmentation seen with the Froment maneuver could have an anatomic basis.

Globus pallidus stimulation improves both motor and nonmotor aspects of quality of life in advanced Parkinson's disease

Our purpose was to measure the change in quality of life (QoL) following deep brain stimulation of the globus pallidus interna (GPi-DBS) in advanced Parkinson 's disease (PD), and identifies any associations with changes in motor features of the disease. Eleven patients (age range 54-69 years, 2 women) underwent GPi-DBS (4 unilateral, 7 bilateral). Outcome measures included assessment of PD-specific QoL (mean 8 months postsurgery) using the PDQ-39 questionnaire, and standard motor assessments. Off-period UPDRS III motor scores fell by (43 +/- 8)% (mean +/- SEM). Dyskinesia severity was reduced on the abnormal involuntary movement scale by (80 +/- 3)% and UPDRS IVa by (58 +/- 8)%. QoL as assessed by the PDQ39SI improved by (30 +/- 5)%, with significant improvements in mobility, activities of daily living, bodily discomfort, emotional wellbeing, communication, and cognitions subscales. Bilateral and unilateral groups demonstrated equivalent PDQ39SI improvement. QoL improvement was highly correlated with dyskinesia reduction but not reduction in UPDRS score or age at surgery. GPi-DBS markedly improves QoL in advanced PD. The impacts are broad and improve QoL domains not directly affected by the motor symptoms of the disease. Reduced dyskinesia plays a major role in the improvement of QoL in GPi-DBS treated patients.

A novel mutation in the central rod domain of lamin A/C producing a phenotype resembling the Emery-Dreifuss muscular dystrophy phenotype

Lamins are the principal components of the nuclear lamina, a network constituting the major structural framework of the nuclear envelope. Alterations in lamin A/C have been associated with a heterogeneous series of human disorders known as laminopathies. We report the finding of a novel deletion in the central rod domain of lamin A/C exon 3 gene in four members of the same family. This genetic alteration was likely responsible for the relatively homogeneous clinical phenotype observed in our three patients, represented by a prominent cardiac conduction-system disease necessitating permanent pacemaker implantation, and limited skeletal involvement manifested by spinal rigidity and contractures. The findings from these cases further expand the clinical spectrum associated with mutations in the LMNA gene.

Mokken scale analysis of the UPDRS: dimensionality of the Motor Section revisited

The dimensionality and reliability of the Motor Section of the Unified Parkinson Disease Rating Scale (UPDRS III) was studied with non-parametric Mokken scale analysis. UPDRS measures were obtained on 147 patients with PD (96 men, 51 women, mean age 61, range 35-80 yrs). Mokken scale analysis revealed a four-dimensional structure of the UPDRS III. Left-sided bradykinesia and rigidity appeared to co-occur with axial signs, gait disturbance, and speech/hypomimia, whereas right-sided bradykinesia and rigidity formed a second scale. Two further small scales were found consisting of right- and left-sided tremor. Results from the scale analysis reveal that all four subscales are strong. The reliability of the two tremor scales is low because they only contain three and four items, respectively.

The effects of focal articular defects on intra-tissue strains in the surrounding and opposing cartilage

Focal damage to articular cartilage is commonly found in symptomatic knees and may contribute to patient discomfort and progressive cartilage degeneration. The objective of this study was to quantify changes in cartilage intra-tissue strain and sliding occurring near a focal defect. Pairs of human osteochondral blocks were compressed by 20% of the total cartilage thicknesses, and tissue deformation was recorded by video microscopy. Then, a single, full-thickness defect was created in one block from each pair, blocks were allowed to re-swell, and the pairs were retested. Stained nuclei, acting as fiducial markers, were tracked by digital image correlation and used to calculate cartilage strains and surface displacement. With intact samples, axial strain decreased with depth, as is typical of cartilage, and relatively little sliding occurred between surfaces. With defect samples, axial compression of cartilage at the defect rim rose by approximately 30%, shear in the opposing tissue increased 10-fold to approximately 0.15, and local sliding was elevated to > 50 microm. In vivo, tissue near a defect likely experiences increased overall compression, magnifying these observed in vitro effects. Excessive strains may contribute to cell death, matrix damage, or accelerated wear, and repair efficacy may depend on the ability to alleviate adverse mechanical conditions.

Enhancement of rigidity in Parkinson's disease with activation

Rigidity, a cardinal symptom of Parkinson's disease (PD), increases with movement of a contralateral limb. It is unclear whether this effect is specific for movement of a contralateral limb. The goal of this study was to test the hypothesis that ipsilateral or contralateral movement would enhance rigidity but that bilateral limb movements would maximally increase rigidity in people with PD. We assessed rigidity in 12 people with PD off meds, 12 matched controls, and 10 young controls, using a Rigidity Analyzer (Neurokinetics, Alberta, Canada). The elbow was passively moved repetitively into flexion and extension by the examiner, while the subjects engaged in different toe tapping conditions: no tapping, ipsilateral tapping, contralateral tapping, and bilateral tapping. Three 50-second trials were done for each condition and the order of the trials was randomized. A 2-way repeated measures ANOVA and Holm-Sidak post hoc tests were used to determine differences across conditions and groups. There was a significant effect of group, tapping conditions and an interaction of the two. Post hoc tests revealed that for the PD group, all tapping conditions were significantly different from the no tapping condition but not different from each other. There were no differences across conditions for the controls. We conclude that movement of either the contralateral or ipsilateral lower extremity can increase arm rigidity in people with PD but the effects from left and right are apparently not additive. Further, activation did not enhance muscle tone in controls suggesting that this procedure may help distinguish people with PD from controls.

Rigid spine syndrome: a radiologic and manometric study of the pharynx and esophagus

The rigid spine syndrome (RSS) is not a recognized cause of dysphagia. The "vacuolar variant" of RSS causes mild, generalized, and slowly progressive weakness. Respiratory evaluation detected severe restrictive chest wall defect and significant respiratory muscle weakness. We identified nine patients at our Neuromuscular Clinic over a period of years. The aim of this evaluation was to ascertain whether pharyngoesophageal dysfunction caused cough (2/9), intermittent oropharyngeal dysphagia (4/9), and aspiration pneumonia (3/9). Pharyngeal and esophageal functions were evaluated separately by conventional cineradiography and intraluminal esophageal manometry over a one-year study period. An age- and gender-matched volunteer group without swallowing complaints partook in the manometric component of the study. There were seven male and two female patients. The mean age of patients was 19.1 years (17.8 years for controls), and the age range was 11-36 years (13-32 years for controls). The mean disease duration was 17.2 years (range=8-31 years). Patients were commonly underweight (7/9). Cineradiology detected abnormal swallow physiology of pharyngeal striated muscle (1/9) and of esophageal smooth muscle (2/9). Mean manometric pressures in patients were not significantly different from control data. Manometry detected "nonspecific" contractility abnormalities (3/9) that were not reflected in the mean data. The relative lack of instrumental findings suggested minor upper alimentary tract dysmotility in patients with the RSS. The myopathy that underlies this syndrome likely caused dysfunction of the striated muscle of the pharyngeal constrictors and upper esophageal sphincter. The documented abnormalities of esophageal smooth muscle motility were nonspecific and tenuously associated with the muscle disorder. The incongruity between complaints of intermittent dysphagia and study results was perhaps due to transient pharyngoesophageal dysmotility, altered swallowing mechanics of limited cervical spine mobility, altered swallowing perception after previous intubation/tracheostomy, or a "functional" upper intestinal complaint.

Extrapyramidal signs, primitive reflexes and incontinence in fronto-temporal dementia

According to the diagnostic consensus criteria [1] akinesia, rigidity and tremor as well as primitive reflexes and incontinence support the diagnosis of fronto-temporal dementia (FTD). However, the prevalence of extrapyramidal signs (EPMS), primitive reflexes and incontinence in FTD has not yet been systematically studied. In the present study, thirty-one patients with mild or moderate FTD without previous or present antipsychotic medication underwent a detailed neurological exam including the motor part of the Unified Parkinson's Disease Rating Scale (UPDRS). The average total score on the motor subscale of the UPDRS was 14.0 points. Akinesia and Parkinsonian gait or posture were found frequently but were mild in most instances. Rigidity was found in 36% of the patients. Resting tremor was a rare symptom. The only primitive reflex that occurred was a positive palmomental that was found in 7% of the patients. Urinary incontinence was present in 26%. The results have to be confirmed with larger or pooled patient samples from different ascertainment scenarios. If the results of the present study can be replicated, a revision of the consensus criteria from 1998 might be considered.

Axial hypertonicity in Parkinson's disease: direct measurements of trunk and hip torque

A cardinal feature of Parkinson's disease (PD) is muscle hypertonicity, i.e. rigidity. Little is known about the axial tone in PD or the relation of hypertonia to functional impairment. We quantified axial rigidity to assess its relation to motor symptoms as measured by UPDRS and determine whether rigidity is affected by levodopa treatment. Axial rigidity was measured in 12 PD and 14 age-matched controls by directly measuring torsional resistance of the longitudinal axis to twisting (+/-10 degrees ). Feet were rotated relative to fixed hips (Hip Tone) or feet and hips were rotated relative to fixed shoulders (Trunk Tone). To assess tonic activity only, low constant velocity rotation (1 degrees /s) and low acceleration (<12 degrees /s(2)) were used to avoid eliciting phasic sensorimotor responses. Subjects stood during testing without changing body orientation relative to gravity. Body parts fixed against rotation could translate laterally within the boundaries of normal postural sway, but could not rotate. PD OFF-medication had higher axial rigidity (p<0.05) in hips (5.07 N m) and trunk (5.30 N m) than controls (3.51 N m and 4.46 N m, respectively), which did not change with levodopa (p>0.10). Hip-to-trunk torque ratio was greater in PD than controls (p<0.05) and unchanged by levodopa (p=0.28). UPDRS scores were significantly correlated with hip rigidity for PD OFF-medication (r values=0.73, p<0.05). Torsional resistance to clockwise versus counter-clockwise axial rotation was more asymmetrical in PD than controls (p<0.05), however, there was no correspondence between direction of axial asymmetry and side of disease onset. In conclusion, these findings concerning hypertonicity may underlie functional impairments of posture and locomotion in PD. The absence of a levodopa effect on axial tone suggests that axial and appendicular tones are controlled by separate neural circuits.

Evaluation of Dopaminergic Function in Frontotemporal Dementia Using 123I-FP-CIT Single Photon Emission Computed Tomography

Extrapyramidal symptoms are observed in frontotemporal dementia (FTD). (123)I-FP-CIT (DaT scan) single photon emission computed tomography (SPECT) can detect loss of presynaptic dopamine transporters in the striatum. We aimed to evaluate the dopaminergic status of the striatum in patients with FTD using DaT scan. Seven patients (age range 65-76 years), who fulfilled the Neary criteria and in whom the diagnosis of FTD was confirmed by hexamethylpropyleneamine oxime SPECT, were included in the study. The severity of the extrapyramidal symptoms was evaluated by the motor part of the Unified Parkinson's Disease Rating Scale (UPDRS). SPECT using (123)I-FP-CIT was done. A (region - occipital)/occipital ratio was calculated for the striatum, putamen and caudate nucleus. The results were compared with those of the 7 age-matched normal controls. The uptake of the radiotracer in the right and left striatum was reduced to 62% (p = 0.000) and 68% (p = 0.000), respectively, compared to controls. The motor UPDRS score of the patients with FTD showed a negative correlation to the uptake of the radiotracer. The presynaptic dopamine transporter in FTD is impaired, related to the severity of the extrapyramidal symptoms. Since an effective treatment for FTD is still to be established, there is a need for evaluating the efficacy of dopaminergic drugs.

Do extrapyramidal features in Alzheimer patients treated with acetylcholinesterase inhibitors predict disease progression?

The objective of the study is to explore the longitudinal course of patients with Alzheimer's disease (AD) with and without extrapyramidal signs (EPS) taking donepezil. A cohort of 106 community-dwelling patients with probable AD receiving donepezil in Sydney, Australia (n = 52) and Manchester, UK (n = 54) was followed over 12 months. Cognition was measured by the Mini-Mental State Exam (MMSE) and the Alzheimer Disease Assessment Scale-Cognitive test (ADAS-Cog) and function by the Alzheimer Disease Cooperative Study-Activities of Daily Living Scale (ADCS-ADL). A further follow-up at five years was conducted to examine mortality and institutionalisation. At baseline, EPS were correlated with MMSE (r = -0.467, p < 0.01), ADAS-Cog (r = 0.485, p < 0.01) and ADCS-ADL (r = -0.526, p < 0.01) scores. Patients with EPS had lower MMSE (F = 9.95, df = 1, p = 0.002) and ADCS-ADL (F = 9.41, df = 1, p = 0.003) scores than patients without EPS. Over one year no time main effects or time x group interaction effects were observed for either dependent variable. At five years patients with EPS were found to have a hazard of institution or death 2.2 times higher than those without EPS (p = 0.018; 95% CI: 1.2, 4.4). There was a positive association between EPS and cognitive and functional impairment. However, EPS did not predict more rapid cognitive or functional decline of patients taking donepezil or response to donepezil. The presence of EPS was a risk factor both for institutionalisation and for death.

Functional recovery in rats with ischemic paraplegia after spinal grafting of human spinal stem cells

Transient spinal cord ischemia in humans can lead to the development of permanent paraplegia with prominent spasticity and rigidity. Histopathological analyses of spinal cords in animals with ischemic spastic paraplegia show a selective loss of small inhibitory interneurons in previously ischemic segments but with a continuing presence of ventral alpha-motoneurons and descending cortico-spinal and rubro-spinal projections. The aim of the present study was to examine the effect of human spinal stem cells (hSSCs) implanted spinally in rats with fully developed ischemic paraplegia on the recovery of motor function and corresponding changes in motor evoked potentials. In addition the optimal time frame for cell grafting after ischemia and the optimal dosing of grafted cells were also studied. Spinal cord ischemia was induced for 10 min using aortic occlusion and systemic hypotension. In the functional recovery study, hSSCs (10,000-30,000 cells/0.5 mul/injection) were grafted into spinal central gray matter of L2-L5 segments at 21 days after ischemia. Animals were immunosuppressed with Prograf (1 mg/kg or 3 mg/kg) for the duration of the study. After cell grafting the recovery of motor function was assessed periodically using the Basso, Beattie and Bresnahan (BBB) scoring system and correlated with the recovery of motor evoked potentials. At predetermined times after grafting (2-12 weeks), animals were perfusion-fixed and the survival, and maturation of implanted cells were analyzed using antibodies recognizing human-specific antigens: nuclear protein (hNUMA), neural cell adhesion molecule (hMOC), neuron-specific enolase (hNSE) and synapthophysin (hSYN) as well as the non-human specific antibodies TUJ1, GFAP, GABA, GAD65 and GLYT2. After cell grafting a time-dependent improvement in motor function and suppression of spasticity and rigidity was seen and this improvement correlated with the recovery of motor evoked potentials. Immunohistochemical analysis of grafted lumbar segments at 8 and 12 weeks after grafting revealed intense hNSE immunoreactivity, an extensive axo-dendritic outgrowth as well as rostrocaudal and dorsoventral migration of implanted hNUMA-positive cells. An intense hSYN immunoreactivity was identified within the grafts and in the vicinity of persisting alpha-motoneurons. On average, 64% of hSYN terminals were GAD65 immunoreactive which corresponded to GABA immunoreactivity identified in 40-45% of hNUMA-positive grafted cells. The most robust survival of grafted cells was seen when cells were grafted 21 days after ischemia. As defined by cell survival and laminar distribution, the optimal dose of injected cells was 10,000-30,000 cells per injection. These data indicate that spinal grafting of hSSCs can represent an effective therapy for patients with spinal ischemic paraplegia.

Biomechanical and electromyogram characterization of neuroleptic-induced rigidity in the rat

Rodent models of Parkinson's disease (PD) are usually assessed using measures of akinesia, but other important parkinsonian symptoms such as rigidity are only rarely quantified. This is in part due to technical difficulties in obtaining such measures in small animals. In the present study we developed quantitative methods to provide time-course assessment of the alternations of muscle tone of parkinsonian rats. A portable and miniature biomechanical stretching device was established to manually stretch the hindlimb of awake rats with muscle rigidity induced by dopamine D2-receptor antagonist raclopride (5 mg/kg, i.p.). From the measured angular displacement angle and reactive torque of sinusoidal stretches at five varied frequencies, viscoelastic components of the muscle tone can be derived. In addition, non-invasive multielectrode was applied to record the tonic and phasic components of the gastrocnemius muscle electromyogram (EMG). Our biomechanical measurements showed not only increase in stiffness (P<0.05) but also increase in viscous components (P<0.05) that matched the time course of increased amplitude of EMG activity (P<0.05). There was a significant positive correlation between all of these measures and akinesia, as measured by the conventional bar-test for catalepsy (with a correlation coefficient of 0.87 at stiffness, 0.92 at viscosity and 0.96 at amplitude of EMG). Phasic contraction counts (PCC) of voluntary EMG exhibited a significantly negative correlation with the bar test scores (correlation coefficient=-0.78). These results confirm that akinesia induced by D2-receptor blockade also induces a rigidity that shares many features with human PD. These novel techniques for quantifying biomechanical and electromyographic parameters provide objective assessment methods for investigating the time-course changes of abnormal muscle tone in rat models of PD that will be useful for evaluating novel treatments.

Four novel mutations of the LHX3 gene cause combined pituitary hormone deficiencies with or without limited neck rotation

CONTEXT

The Lhx3 LIM-homeodomain transcription factor gene is required for development of the pituitary and motoneurons in mice. Human LHX3 gene mutations have been reported in five subjects with a phenotype consisting of GH, prolactin, TSH, LH, and FSH deficiency; abnormal pituitary morphology; and limited neck rotation.

OBJECTIVE

The objective of the study was to determine the frequency and nature of LHX3 mutations in patients with isolated GH deficiency or combined pituitary hormone deficiency (CPHD) and characterize the molecular consequences of mutations.

DESIGN

The LHX3 sequence was determined. The biochemical properties of aberrant LHX3 proteins resulting from observed mutations were characterized using reporter gene and DNA binding experiments.

PATIENTS

The study included 366 patients with isolated GH deficiency or CPHD.

RESULTS

In seven patients with CPHD from four consanguineous pedigrees, four novel, recessive mutations were identified: a deletion of the entire gene (del/del), mutations causing truncated proteins (E173ter, W224ter), and a mutation causing a substitution in the homeodomain (A210V). The mutations were associated with diminished DNA binding and pituitary gene activation, consistent with observed hormone deficiencies. Whereas subjects with del/del, E173ter, and A210V mutations had limited neck rotation, patients with the W224ter mutation did not.

CONCLUSIONS

LHX3 mutations are a rare cause of CPHD involving deficiencies for GH, prolactin, TSH, and LH/FSH in all patients. Whereas most patients have a severe hormone deficiency manifesting after birth, milder forms can be observed, and limited neck rotation is not a universal feature of patients with LHX3 mutations. This study extends the known molecular defects and range of phenotypes found in LHX3-associated diseases.

Rigidity and spasms from autoimmune encephalomyelopathies: stiff-person syndrome

Stiff-person syndrome (SPS) is a disorder characterized by progressive muscle rigidity with superimposed painful muscle spasms and gait impairment due to continuous motor activity. Evidence has accumulated in favor of SPS representing an autoimmune, predominantly encephalomyelopathic disorder resulting from B-cell-mediated clonal production of autoantibodies against presynaptic inhibitory epitopes on the enzyme glutamic acid decarboxylase (GAD) and the synaptic membrane protein amphiphysin. Recognition of the clinical spectrum of SPS is important, particularly the upper-limb, cervical, and cranial nerve involvement that occurs in paraneoplastic variants. The correlation between antibody levels and severity of disease offers evidence for a pathogenic role for the anti-GAD and anti-amphiphysin autoantibodies. The scarcity of neuropathological correlates stand in sharp contrast with the severity of the disability in affected individuals and suggests that functional impairment of inhibitory circuits without structural damage is sufficient to develop the full clinical spectrum of SPS. The rarity of this condition limits the feasibility of controlled clinical trials in the treatment of SPS, but the available evidence suggest that drugs that increase cortical and spinal inhibition such as benzodiazepines and drugs that provide immune modulation such as intravenous immunoglobulin, plasmapheresis, and prednisone are effective treatments.

Quantitative measurement of trunk rigidity in parkinsonian patients

We aimed to develop an objective measurement to quantify trunk rigidity in patients with Parkinson's disease (PD), and to examine its reliability, validity and sensitivity in differentiating PD patients from control subjects. In Study 1, an isokinetic dynamometer was employed to assess trunk rigidity in 6 PD patients and 6 healthy controls. Passive trunk flexion and extension at 4 angular velocities were applied and resistive torques were recorded. Both work done and resistive peak torques to passive trunk flexion (Torque(PF)) and extension (Torque(PE)) were found to be highly reliable within a 2-day interval in PD patients and control subjects. In Study 2, trunk muscle tone was compared between 15 PD and 15 control subjects. Significantly higher muscle tone, as shown by increases in work done, and in Torque(PF) and Torque(PE )at higher movement speeds, was found in PD patients. Within each subject group, resistive trunk muscle tone was found to increase with increasing velocity of passive movement, but the extent of increase was greater in PD patients. Our results thus suggest that the objective method developed by us was reliable and could differentiate trunk rigidity in PD patients from that of healthy subjects.

Role of hyperactive cerebellum and motor cortex in Parkinson's disease

Previous neuroimaging studies have found hyperactivation in the cerebellum and motor cortex and hypoactivation in the basal ganglia in patients with Parkinson's disease (PD) but the relationship between the two has not been established. This study examined whether cerebellar and motor cortex hyperactivation is a compensatory mechanism for hypoactivation in the basal ganglia or is a pathophysiological response that is related to the signs of the disease. Using a BOLD contrast fMRI paradigm PD patients and healthy controls performed automatic and cognitively controlled thumb pressing movements. Regions of interest analysis quantified the BOLD activation in motor areas, and correlations between the hyperactive and hypoactive regions were performed, along with correlations between the severity of upper limb rigidity and BOLD activation. There were three main findings. First, the putamen, supplementary motor area (SMA) and pre-SMA were hypoactive in PD patients. The left and right cerebellum and the contralateral motor cortex were hyperactive in PD patients. Second, PD patients had a significant negative correlation between the BOLD activation in the ipsilateral cerebellum and the contralateral putamen. The correlation between the putamen and motor cortex was not significant. Third, the BOLD activation in the motor cortex was positively correlated with the severity of upper limb rigidity, but the BOLD activation in the cerebellum was not correlated with rigidity. Further, the activation in the motor cortex was not correlated with upper extremity bradykinesia. These findings provide new evidence supporting the hypothesis that hyperactivation in the ipsilateral cerebellum is a compensatory mechanism for the defective basal ganglia. Our findings also provide the first evidence from neuroimaging that hyperactivation in the contralateral primary motor cortex is not a compensatory response but is directly related to upper limb rigidity.

Progressive supranuclear palsy

Since progressive supranuclear palsy (PSP) was first reported as a separate clinicopathological entity in 1964, hundreds of other cases have been recorded, and PSP is now one of the most common atypical Parkinson-plus disorders. Diagnostic criteria have been developed by the National Institute of Neurological Disorders and Stroke and the Society for PSP, Inc. Because there is no biological marker for PSP, definitive diagnosis depends on neuropathological examination. Characteristics of PSP include gait disturbances, supranuclear ophthalmoplegia, axial limb rigidity, and frontal lobe dysfunction. Although there are no treatments that alter the natural history of disease in PSP and no drugs that provide significant symptomatic benefits, several supportive measures are available.

Vitamin A deficiency alters pulmonary parenchymal collagen and tissue mechanics

The mechanical properties of the pulmonary parenchyma are strongly influenced by the collagen and elastic fibers that course through the alveolar interstitium and interconnect the bronchovascular bundles. Vitamin A deficiency (VAD) produces effacement and remodeling of the alveolar architecture, resulting in alternating areas of alveolar dilatation and collapse. To better understand the mechanical consequences and reversibility of this remodeling process, we have examined how the remodeling of collagen and elastic fibers correlates with the mechanical properties of the lung parenchyma in VAD rats. An oscillatory impulse was applied at different levels of stress on the fiber network and the tissue damping (G), elastance (H), hysteresivity (G/H, eta) were analyzed. At a supra-physiological functional residual capacity, the lung parenchyma of VAD rats exhibited a lower G and H than Vitamin A sufficient (VAS) rats, which was accompanied by a significant decrease in the quantity of parenchymal collagen and collagen fibers. Retinoic acid (RA) administration restored the parenchymal collagen and mechanical properties.

A comparison of the effects of imposed extension and flexion movements on Parkinsonian rigidity

OBJECTIVE

To test a hypothesis that Parkinsonian rigidity is more pronounced in imposed extension than flexion movement.

METHODS

Twelve Parkinsonian subjects (both "Off" and "On" medication states) and seven control subjects participated in the protocol, in which a servomotor imposed wrist flexion and extension. Rigidity was quantitatively evaluated by the rectified torque integral with time, i.e., temporal score, and by the torque integral with joint angle, i.e., work score, for extension and flexion, respectively.

RESULTS

In the "Off" state, the imposed extension induced a significantly higher resistance than did flexion. Dopaminergic medication significantly reduced the temporal score associated with imposed extension, and significantly decreased the work score of both movements. Compared with controls, the scores were higher for patients in the "On" state.

CONCLUSIONS

Rigidity is more readily elicited in extension movement. The distinction is not evident in clinical practice, whereas it can be clearly revealed with the application of biomechanical analyses.

SIGNIFICANCE

This distinction may prove to be a standard feature of rigidity. The procedures may be helpful in diagnosis and useful in evaluating new treatments and developing rehabilitation programs.

Role of reflex dynamics in spinal stability: intrinsic muscle stiffness alone is insufficient for stability

Spinal stability is related to both the intrinsic stiffness of active muscle as well as neuromuscular reflex response. However, existing analyses of spinal stability ignore the role of the reflex response, focusing solely on the intrinsic muscle stiffness associated with voluntary activation patterns in the torso musculature. The goal of this study was to empirically characterize the role of reflex components of spinal stability during voluntary trunk extension exertions. Pseudorandom position perturbations of the torso and associated driving forces were recorded in 11 healthy adults. Nonlinear systems-identification analyses of the measured data provided an estimate of total systems dynamics that explained 81% of the movement variability. Proportional intrinsic response was less than zero in more than 60% of the trials, e.g. mean value of P(INT) during the 20% maximum voluntary exertion trunk extension exertions -415+/-354N/m. The negative value indicated that the intrinsic muscle stiffness was not sufficient to stabilize the spine without reflex response. Reflexes accounted for 42% of the total stabilizing trunk stiffness. Both intrinsic and reflex components of stiffness increased significantly with trunk extension effort. Results reveal that reflex dynamics are a necessary component in the stabilizing control of spinal stability.

Striatal FP-CIT uptake differs in the subtypes of early Parkinson's disease

In idiopathic Parkinson's disease (PD), a tremor-dominant type (TDT), an akinetic-rigid type (ART), and a mixed type (MT) are distinguished. We compared cerebral [I-123]FP-CIT SPECT in the PD subtypes (67 patients Hoehn and Yahr stage 1:26 with ART, 19 with MT, 22 with TDT). We measured the ratios putamen/occipital lobe binding and caudate nucleus/occipital lobe binding. Parkinsonian motor symptoms were quantified by UPDRS motor scale. In both putamen and caudate nucleus contralateral to the clinically affected body side TDT patients showed a significantly higher FP-CIT uptake than ART or MT patients (ANOVA; p<0.01). Contralateral putamen and caudate nucleus FP-CIT uptake correlated significantly with severity of rigidity (p<0.01) and hypokinesia (p<0.01) but not with severity of resting or postural tremor (p>0.05). The missing correlation between striatal FP-CIT uptake and tremor suggests, that further systems besides the nigrostriatal dopaminergic system may contribute to generation of parkinsonian tremor.

Progression of Parkinson’s Disease following Thalamic Deep Brain Stimulation for Tremor

We assessed the long-term effect of thalamic deep brain stimulation (DBS) on motor symptoms and progression of Parkinson's disease (PD) in PD patients treated for resting and postural/action tremor. Thalamic DBS was performed in 17 patients with treatment-resistant resting and postural/action tremor. Nine patients were available for follow-up examination a mean of 5.5 years after surgery. Three had tremor-dominant PD. DBS produced marked improvement in resting and postural/action tremor in target upper extremity in all 9 patients, which persisted unchanged at the time of the last follow-up visit 5.5 years after surgery. PD severity with DBS 'on' and 'off' 1 year after surgery was compared to PD severity at the last follow-up visit using UPDRS (Unified Parkinson's Disease Rating Scale) III motor scores and individual motor item subscores. Patients were tested while on medication. There was no significant worsening of tremor, rigidity, speech, postural stability, gait, or axial bradykinesia with DBS either on or off at the last follow-up visit compared to the 12-month visit. UPDRS III motor scores were unchanged. However, global assessment of PD progression and increased mean L-dopa dose and L-dopa equivalent daily dose at the time of last follow-up visit indicated that a progression of PD had occurred.

Anatomy of a hypnotic response: Self-report estimates, actual behavior, and physiological response to the hypnotic suggestion for arm rigidity

The present study closely examines subject response to the arm-rigidity item of the HGSHS:A. Subject behavior, subject self-report, and surface EMG of the biceps and triceps muscles were monitored. Two distinct ways of passing the item were observed and verified by EMG recordings: some subjects (tremblers) exerted muscular effort to bend the arm and kept it rigidly straight. Others (nontremblers) passively kept the arm straight without exerting muscular effort to bend, even though they reported exerting effort to bend their arm. These two behaviorally and physiologically different methods of passing the item support the idea of individual differences in hypnotic responding and suggest that subjects may be using different mental processes to pass the item.

Selenoprotein N muscular dystrophy: differential diagnosis for early-onset limited mobility of the spine

Early spinal rigidity is a nonspecific feature reported in diseases such as neuromuscular and central movement disorders. We present a male patient with rigid spine muscular dystrophy caused by newly identified compound heterozygote mutations of the selenoprotein N gene and discuss this disease as a possible differential diagnosis for early-onset reduced spine mobility. Rigid spine muscular dystrophy is a rare myopathy presenting in childhood with a typical combination of stable or slowly progressive mild to moderate muscle weakness, limitation in flexion of the spine, and progressive restrictive ventilatory disorder. The clinical features of our patient include early-onset rigidity of his spine, scoliosis, mild muscular weakness predominantly of neck and trunk flexors, and restrictive ventilatory disorder. Biopsy of the biceps muscle revealed nonspecific myopathic changes, and molecular analysis confirmed the diagnosis of rigid spine muscular dystrophy. Thus, neuromuscular diseases such as muscular dystrophy must be considered in all patients presenting with early spinal rigidity, and genetic determination is a possible way to determine the diagnosis.

Association between mild parkinsonian signs and mild cognitive impairment in a community

BACKGROUND

Mild parkinsonian signs (MPS) are associated with prevalent and incident dementia but it is not known whether they are associated with mild cognitive impairment (MCI).

OBJECTIVE

To determine whether MPS and specific MPS (changes in axial function, rigidity, tremor) are associated with MCI in nondemented community-dwelling older people in northern Manhattan, NY.

METHODS

Participants underwent neurologic assessment, including a modified motor portion of the Unified Parkinson Disease Rating Scale. MCI was diagnosed in nondemented participants who had cognitive impairment based on neuropsychological testing and no functional impairment. Participants with MCI were classified as having MCI with memory impairment (MCI+M) vs MCI without memory impairment (MCI-M).

RESULTS

MCI was present in 608 (27.3%) of 2,230 participants, including 255 participants with MCI+M and 353 with MCI-M; 1,622 participants did not have MCI. MPS were present in 369 (16.5%) of 2,230 participants. In a univariate logistic regression model, odds of MCI+M (vs no MCI) were 51% higher in participants with MPS compared to those with no MPS (OR = 1.51, 95% CI = 1.09 to 2.09, p = 0.01). Multivariate models yielded similar results (OR = 1.45, 95% CI = 1.03 to 2.05, p = 0.03). Rigidity was present in a higher proportion of participants with MCI+M compared to participants without MCI.

CONCLUSIONS

Mild parkinsonian signs, especially rigidity, are associated with amnestic mild cognitive impairment. Mild parkinsonian signs and mild cognitive impairment may share similar pathogeneses. Whether this involves Alzheimer-type pathology, Lewy bodies, or vascular changes in the basal ganglia or basal ganglia circuitry deserves further investigation in postmortem studies.