Orthostatic tremor: A review of 45 cases

ObjectiveTo evaluate the clinical characteristics, associated features, and treatment response of a large orthostatic tremor series seen over a 26-year period.MethodsWe reviewed the medical records of 45 patients seen between 1987 and 2013 who fulfilled the diagnostic criteria for orthostatic tremor.ResultsThe mean age at onset was 59.5 years and 23/45 (51%) were men. A family history of any tremor was noted in 23/45 (51%) patients. A family history of orthostatic tremor was reported in 3/45 (7%) patients. 40/45 (89%) had primary orthostatic tremor with (n = 30) or without (n = 10) an associated postural arm tremor. We found that 5/45 (11%) had orthostatic tremor plus additional neurological features. One patient was diagnosed with dementia with Lewy bodies preceded by orthostatic tremor for 20 years. Prospective follow-up data was available for 30/45 patients and averaged 54.4 months. Treatment response to medications was modest and inconsistent. In 11/30 cases, orthostatic tremor worsened over the follow-up period. One patient with primary orthostatic tremor underwent thalamic deep brain stimulation surgery.ConclusionsIn our population of orthostatic tremor patients, mild postural hand tremor was a frequent finding. Over half of our patients had a family history of tremor, but a family history of orthostatic tremor was uncommon. Additional neurological features were seen in the minority of patients and we report possibly the first case of dementia with Lewy bodies associated with orthostatic tremor. Our series is the largest series of orthostatic tremor reported in the literature and contributes to understanding the clinical characteristics of this rare disease.     

Triggering essential head tremor with sustained phonation: A clinical phenomenon with potential diagnostic value

Here we report a clinical phenomenon that we have observed repeatedly in clinical research settings; namely, a triggering and/or exacerbation of head tremor during or immediately following sustained phonation. To our knowledge, it has not been reported previously nor has it been the subject of study. Here we: 1) report the phenomenon, 2) provide several visual illustrations, 3) estimate its prevalence, and 4) analyze its clinical correlates. Head tremor was assessed qualitatively, and scores were assigned pre-, during, and post-sustained phonation using the Tremor Research Group Essential Tremor Rating Assessment Scale. Seventy (68.6%) of 102 essential tremor (ET) patients exhibited a qualitative increase in head tremor amplitude during and/or immediately after sustained phonation; in 5 (4.9%), head tremor would not have been detected without the voice activation maneuver (i.e., it was not visible at any other point in the videotape aside from the period during/immediately following sustained phonation). Women were more likely than men to exhibit this phenomenon (p = 0.05), whereas age, age at onset, duration of tremor, and total tremor score did not predict responsiveness of head tremor to sustained phonation. Sustained voice activation is a useful examination maneuver that may elicit or amplify head tremor in ET. Head tremor is not reported to occur in patients with enhanced physiological tremor. Thus, this maneuver, by triggering head tremor, may be a useful diagnostic supplement, particularly in research/clinical settings where arm tremor is mild and the diagnosis (mild ET vs. enhanced physiological tremor) would otherwise be ambiguous.     

Different effects of essential tremor and Parkinsonian tremor on multiscale dynamics of hand tremor

ObjectiveEssential tremor (ET) and Parkinsonian tremor (PT) are often clinically misdiagnosed due to the overlapping characteristics of their hand tremor. We aim to examine if ET and PT influence the multiscale dynamics of hand tremor, as quantified using complexity, differently, and if such complexity metric is of promise to help identify ET from PT.MethodsForty-eight participants with PT and 48 with ET performed two 30-second tests within each of the following conditions: sitting while resting arms or outstretching arms horizontally. The hand tremor was captured by accelerometers secured to the dorsum of each hand. The complexity was quantified using multiscale entropy.ResultsCompared to PT group, ET group had lower complexity of both hands across conditions (F > 34.2, p < 0.001). Lower complexity was associated with longer disease duration (r² > 0.15, p < 0.009) in both PT and ET, and within PT, greater Unified Parkinson's Disease Rating Scale-III UPDRS-III scores (r² > 0.18, p < 0.009). Receiver-operating-characteristic curves revealed that the complexity metric can distinguish ET from PT (area-under-the-curve > 0.77, cut-off value = 48 (postural), 49 (resting)), which was confirmed in a separate dataset with ET and PT that were clearly diagnosed in prior work.ConclusionsThe PT and ET have different effects on hand tremor complexity, and this metric is promising to help the identification of ET and PT, which still needs to be confirmed in future studies.SignificanceThe characteristics of multiscale dynamics of the hand tremor, as quantified by complexity, provides novel insights into the different pathophysiology between ET and PT.     

Effect of lead trajectory on the response of essential head tremor to deep brain stimulation

BackgroundEssential tremor (ET) is one of the most common movement disorders. Normally ET affects the distal upper extremities, but it can also be accompanied by midline symptoms. Ventralis intermedius (VIM) thalamic deep brain stimulation (DBS) has been shown to be effective in reducing hand tremor, but its effects on head tremor have been inconsistent.MethodsTwenty-nine DBS patients with a diagnosis of ET met inclusion criteria. All implantations targeted VIM. The factors examined included age, gender, disease duration, presence or absence of head tremor, handedness, and the Fahn-Tolosa-Marin rating scale (TRS). This analysis specifically focused on TRS head tremor sub-scores at baseline, 6 months and 12 months post-DBS. Additionally, DBS lead entry angles were examined.ResultsTwenty-three ET patients underwent unilateral DBS and six underwent staged bilateral DBS. At both 6 and 12 months following DBS, stimulation resulted in diminished head tremor (ON vs OFF; p < 0.0001). The most important predictor of head tremor suppression was the entry angle of the DBS lead in the sagittal projection relative to the AC–PC axial plane (AC–PC angle). Head tremor reduction was greater among more vertical AC–PC angles.ConclusionA more vertical AC–PC angle of the DBS lead trajectory was associated with improved head tremor suppression. Further studies will be necessary to confirm this potentially important finding.     

Tremor is attenuated during walking in essential tremor with resting tremor but not parkinsonian tremor

We used accelerometry and visual examination by a neurologist to measure the intensity and frequency of hand tremor under resting, postural, writing, and walking conditions among patients with essential tremor with resting tremor (n = 11) and Parkinson’s disease (n = 38). The intensity of essential tremor was markedly attenuated during walking relative to resting. The intensity and frequency of parkinsonian tremors were higher while walking than while resting. We suggest that assessment of the intensity and frequency of tremor during walking is clinically useful for differentiating between essential tremor with resting tremor and parkinsonian tremor, especially in the early stages, when the two conditions are often difficult to distinguish. Parkinsonian tremors are known to be enhanced during walking. Our clinical experience, as well as that of others, suggests that the intensity of essential tremor with resting tremor is markedly attenuated during walking.     

The diagnostic value of clinical neurophysiology in hyperkinetic movement disorders: A systematic review

IntroductionTo guide the neurologist and neurophysiologist with interpretation and implementation of clinical neurophysiological examinations, we aim to provide a systematic review on evidence of electrophysiological features used to differentiate between hyperkinetic movement disorders.MethodsA PRISMA systematic search and QUADAS quality evaluation has been performed in PubMed to identify diagnostic test accuracy studies comparing electromyography and accelerometer features. We included papers focusing on tremor, dystonia, myoclonus, chorea, tics and ataxia and their functional variant. The features were grouped as 1) basic features (e.g., amplitude, frequency), 2) the influence of tasks on basic features (e.g., entrainment, distraction), 3) advanced analyses of multiple signals, 4) and diagnostic tools combining features.ResultsThirty-eight cross-sectional articles were included discussing tremor (n = 28), myoclonus (n = 5), dystonia (n = 5) and tics (n = 1). Fifteen were rated as ‘high quality’. In tremor, the basic and task-related features showed great overlap between clinical tremor syndromes, apart from rubral and enhanced physiological tremor. Advanced signal analyses were best suited for essential, parkinsonian and functional tremor, and cortical, non-cortical and functional jerks. Combinations of electrodiagnostic features could identify essential, enhanced physiological and functional tremor.ConclusionStudies into the diagnostic accuracy of electrophysiological examinations to differentiate between hyperkinetic movement disorders have predominantly been focused on clinical tremor syndromes. No single feature can differentiate between them all; however, a combination of analyses might improve diagnostic accuracy.     

Head tremor in essential tremor: “Yes–yes”, “no–no”, or “round and round”?

IntroductionEssential tremor (ET) is a common yet frequently misdiagnosed movement disorder. One contributing factor may be the dearth of studies that focus on the nuances of clinical phenomenology. A clinical feature that has received relatively little attention is head tremor. Indeed, there is no consensus regarding the predominant direction of head tremor in ET, and no study has examined the clinical correlates of directionality.MethodsWe identified 51 ET cases with head tremor enrolled in a clinical-epidemiological study of ET at Columbia University. Each had a videotaped neurological examination. Videotapes were viewed and coded by a movement disorders neurologist for head tremor direction (“no–no”, “yes–yes”, or mixed) and continuity (continuous, intermittent, or rare). Direction was correlated with a wide range of clinical features.ResultsFourteen cases (27.5%) had “no–no” tremor, 9 (17.6%) had “yes–yes” tremor, and 28 (54.9%) had a mixed tremor. Mixed and “yes–yes” cases were older (p = 0.004) and had a longer tremor duration (p = 0.018) than “no–no” cases. Tremor severity (arms) was higher for mixed cases than for “yes–yes” and “no–no” cases (p = 0.04). More mixed cases had continuously present tremor while more “no–no” cases had rare head tremor (p < 0.001).ConclusionsHead tremor in ET seems to start as an infrequent tremor in one direction (esp. “no–no”) and becomes more frequent while acquiring additional directionality and a mixed phenotype as the disease progresses. These findings add to our understanding of the clinical spectrum of ET.     

Rest tremor suppression may separate essential from parkinsonian rest tremor

Rest tremor at 4–6 Hz is typical for classical rest tremor (PT) of Parkinson's disease (PD). But rest tremor also appears in other tremor syndromes and may therefore cause a misdiagnosis. In this study we evaluated if suppression of tremor during movement onset is a characteristic feature of Parkinsonian Tremor distinguishing PT from Essential tremor (ET) and if this sign can be reliably diagnosed.Clinically diagnosed patients with PT (n = 44) and ET (n = 22) with rest tremor were included. Video sequences were recorded according to a standardized protocol focusing on the change of tremor amplitude during transition from rest to posture (test 1) or to a target-directed movement (test 2). These videos were assessed for rest tremor suppression by 4 reviewers (2 specialists and 2 residents) blinded to the clinical diagnosis and were compared to the personal assessment of an unblinded movement disorder specialist.Rest tremor suppression was found in 39/44 PD patients and in 2/22 patients with ET during the personal assessment. Rest tremor suppression showed a high sensitivity (0.92–1.00) and an acceptable specificity (0.69–0.95) for PD tremor in both tests. The interrater-reliability of the video-sequences was good to very good (κ 0.73–0.91). Less than 3% of the video sequences were misclassified.We conclude that the assessment of the suppression of rest tremor during movement initiation is a simple and reliable tool to separate PT from rest tremor in ET also suggesting that the mechanisms of rest tremor in these two diseases are different.     

Tremor and Quality of Life in Patients With Advanced Essential Tremor Before and After Replacing Their Standard Deep Brain Stimulation With a Directional System

ObjectivesPatients with essential tremor treated with thalamic deep brain stimulation may experience increased tremor with the progression of their disease. Initially, this can be counteracted with increased stimulation. Eventually, this may cause unwanted side-effects as the circumferential stimulation from a standard ring contact spreads into adjacent regions. Directional leads may offer a solution to this clinical problem. We aimed to compare the ability of a standard and a directional system to reduce tremor without side-effects and to improve the quality of life for patients with advanced essential tremor.Materials and MethodsSix advanced essential tremor patients with bilateral thalamic deep brain stimulation had their standard system replaced with a directional system. Tremor rating scale scores were prospectively evaluated before and after the replacement surgery. Secondary analyses of quality of life related to tremor, voice, and general health were assessed.ResultsThere was a significantly greater reduction in tremor without side-effects (p = 0.017) when using the directional system. There were improvements in tremor (p = 0.031) and voice (p = 0.037) related quality of life but not in general health for patients using optimized stimulation settings with the directional system compared to the standard system.ConclusionsIn this cohort of advanced essential tremor patients who no longer had ideal tremor reduction with a standard system, replacing their deep brain stimulation with a directional system significantly improved their tremor and quality of life. Up-front implantation of directional deep brain stimulation leads may provide better tremor control in those patients who progress at a later time point.     

Clinical features and nigrostriatal dysfunction in patients with combined postural and resting tremors

BackgroundThe characteristics of clinical features and nigrostriatal dopaminergic dysfunction in patients with combined postural and resting tremors have been less clearly reported.MethodsThe present study examined 43 patients with a visible persistent bilateral postural tremor and a unilateral/bilateral resting tremor involving the hands and forearms. The patients had experienced tremors for more than 3 years, with no evidence of Parkinson's disease or other parkinsonian disorders. Visual and quantitative analyses of [¹⁸F] N-(3-fluoropropyl)-2beta-carbon ethoxy-3beta-(4-iodophenyl) nortropane (FP-CIT) PET in 36 patients were performed. Seventeen age-matched normal controls were also studied.ResultsOn visual analysis, 28 patients (78%) showed normal [¹⁸F] FP-CIT uptake and eight (22%) showed significantly reduced uptake, suggesting nigrostriatal dopaminergic neuronal degeneration. The reduced [¹⁸F] FP-CIT uptake was significantly associated with earlier age-at-onset of tremor and asymmetric presentation of resting tremor. On quantitative analysis, there were statistically significant differences in the [¹⁸F] FP-CIT uptake ratio in the posterior putamen between patients with reduced uptake (2.37 ± 1.83) and patients with normal uptake (6.39 ± 1.35) (P < 0.001). However, posterior putamen uptake levels in patients with normal [¹⁸F] FP-CIT uptake on visual analysis were similar to those in normal controls (7.22 ± 1.29) (P = 0.291).ConclusionThe nigrostriatal dopaminergic dysfunction in patients with combined postural and resting tremors may be associated with earlier age-at-onset of tremor and asymmetric pattern of resting tremor, which might help to correctly diagnose patients with mixed tremors.     

Embarrassment in essential tremor: Prevalence,clinical correlates and therapeutic implications

BackgroundEmbarrassment is a commonly described feature of essential tremor (ET) but has not been the focus of clinical research.ObjectiveTo estimate the prevalence, identify susceptible patient groups, and quantify the therapeutic correlates of reported embarrassment.MethodsA total of 106 ET cases from a population-based sample and 349 ET cases from a clinical sample were asked, “Does your tremor often embarrass you?”ResultsIn the clinical sample, the prevalence of embarrassment was high (58.2%). Even in those ET cases with no head tremor and mild arm tremor, nearly one-half (29/61 [47.5%]) reported embarrassment. While the prevalence of embarrassment was lower in the population-based sample, it was not negligible (18.9%). Embarrassment was associated with younger age of onset (p = 0.003) and women were nearly twice as likely as men to report embarrassment (OR = 1.85, p = 0.01). Independent of tremor severity, embarrassment nearly doubled the odds of using tremor medication (OR = 1.86, p = 0.01).ConclusionsEmbarrassment may be a source of disability in ET. Even among clinic patients with mild tremor, nearly one-half reported embarrassment. We identified a number of patient characteristics linked to embarrassment. Embarrassment alone (i.e., independent of tremor severity) was responsible for a doubling of tremor medication usage. The majority of clinical trials do not assess the therapeutic effects of medication on embarrassment. These trials may benefit from scaled assessments of level of embarrassment.     

Characterizing vocal tremor in progressive neurological diseases via automated acoustic analyses

ObjectiveVoice tremor represents a common but frequently overlooked clinical feature of neurological disease. Therefore, we aimed to quantitatively and objectively assess the characteristics of voice tremor in a large sample of patients with various progressive neurological diseases.MethodsVoice samples were acquired from 240 patients with neurological disease and 40 healthy controls. The robust automated method was designed, allowing precise tracking of multiple tremor frequencies and distinguish pathological from the physiological tremor.ResultsAbnormal tremor was revealed in Huntington’s disease (65%), essential tremor (50%), multiple system atrophy (40%), cerebellar ataxia (40%), amyotrophic lateral sclerosis (40%), progressive supranuclear palsy (25%), Parkinson’s disease (20%), cervical dystonia (10%), and multiple sclerosis (8%) but not in controls. Low-frequency voice tremor (<4 Hz) was common in all investigated diseases, whereas medium tremor frequencies (4–7 Hz) were specific for movement disorders of Parkinson’s disease, multiple system atrophy, essential tremor, and cervical dystonia.ConclusionsCareful estimation of vocal tremor may help with accurate diagnosis and tailored treatment.SignificanceThis study provides (i) more insights into the pathophysiology of vocal tremor in a wide range of neurological diseases and (ii) an accurate method for estimation of vocal tremor suitable for clinical practice.     

Thalamic DBS with a constant-current device in essential tremor: A controlled clinical trial

IntroductionThis study of thalamic deep brain stimulation (DBS) investigated whether a novel constant-current device improves tremor and activities of daily living (ADL) in patients with essential tremor (ET).MethodsA prospective, controlled, multicenter study was conducted at 12 academic centers. We investigated the safety and efficacy of unilateral and bilateral constant-current DBS of the ventralis intermedius (VIM) nucleus of the thalamus in patients with essential tremor whose tremor was inadequately controlled by medications. The primary outcome measure was a rater-blinded assessment of the change in the target limb tremor score in the stimulation-on versus stimulation-off state six months following surgery. Multiple secondary outcomes were assessed at one-year follow-up, including motor, mood, and quality-of-life measures.Results127 patients were implanted with VIM DBS. The blinded, primary outcome variable (n = 76) revealed a mean improvement of 1.25 ± 1.26 points in the target limb tremor rating scale (TRS) score in the arm contralateral to DBS (p < 0.001). Secondary outcome variables at one year revealed significant improvements (p ≤ 0.001) in quality of life, depression symptoms, and ADL scores. Forty-seven patients had a second contralateral VIM-DBS, and this group demonstrated reduction in second-sided tremor at 180 days (p < 0.001). Serious adverse events related to the surgery included infection (n = 3), intracranial hemorrhage (n = 3), and device explantation (n = 3).ConclusionUnilateral and bilateral constant-current VIM DBS significantly improves upper extremity tremor, ADL, quality of life, and depression in patients with severe ET.     

Somatosensory temporal discrimination in essential tremor and isolated head and voice tremors

The aim of this study was to investigate the somatosensory temporal discrimination threshold in patients with essential tremor (sporadic and familial) and to evaluate whether somatosensory temporal discrimination threshold values differ depending on the body parts involved by tremor. We also investigated the somatosensory temporal discrimination in patients with isolated voice tremor. We enrolled 61 patients with tremor: 48 patients with essential tremor (31 patients with upper limb tremor alone, nine patients with head tremor alone, and eight patients with upper limb plus head tremor; 22 patients with familial vs. 26 sporadic essential tremor), 13 patients with isolated voice tremor, and 45 healthy subjects. Somatosensory temporal discrimination threshold values were normal in patients with familial essential tremor, whereas they were higher in patients with sporadic essential tremor. When we classified patients according to tremor distribution, somatosensory temporal discrimination threshold values were normal in patients with upper limb tremor and abnormal only in patients with isolated head tremor. Temporal discrimination threshold values were also abnormal in patients with isolated voice tremor. Somatosensory temporal discrimination processing is normal in patients with familial as well as in patients with sporadic essential tremor involving the upper limbs. By contrast, somatosensory temporal discrimination is altered in patients with isolated head tremor and voice tremor. This study with somatosensory temporal discrimination suggests that isolated head and voice tremors might possibly be considered as separate clinical entities from essential tremor. © 2015 International Parkinson and Movement Disorder Society     

The clinical features and functional impact of valproate-induced tremor

BackgroundTremor is a known side-effect of anticonvulsants, particularly of valproate. However, there is a dearth of information regarding detailed clinical features and functional impact of valproate-induced tremor.MethodsWe studied a cohort of patients treated with anticonvulsants for neurological disorders, through blinded evaluations using the Clinical Rating Scale for Tremor (CRST); we compared the frequency, severity and functional impact of drug-induced tremor between patients treated with valproate and those treated with other anticonvulsants.ResultsFrom a cohort of 218 consecutive patients, 171 were fully evaluated; 118 patients were taking valproate alone or combined with other anticonvulsants and 53 patients were taking other anticonvulsants. Mean age (±SD) at evaluation of the cohort was 32 ± 13 years, females represented 55.6% of cases. Tremor was more frequently observed in patients taking valproate particularly postural upper limb tremor: 49% vs. 15% (right-side) (P < 0.001) and 48.3% vs. 13.2% (left-side), (P < 0.001); had a higher total CRST score: 12.14 vs. 3.06 (P < 0.001), and required more frequently treatment for drug-induced tremor: 23.7% vs. 5.6% (P=0.005) compared with patients taking other anticonvulsants. Among 118 patients taking valproate, women had a higher total CRST score compared with men: 14.54 ± 14.9 vs. 9.56 ± 9.55 (P=0.034). A weak correlation between the total CRST score, dose per Kg of valproate and serum levels of valproate were observed.ConclusionsTremor is frequently observed in patients taking valproate and is severe enough to require treatment in about 24% of cases.     

Tremor retrainment as therapeutic strategy in psychogenic (functional) tremor

BackgroundEntrainment, the change or elimination of tremor as patients perform a voluntary rhythmical movement by the unaffected limb, is a key diagnostic hallmark of psychogenic tremor.ObjectiveTo evaluate the feasibility of using entrainment as a bedside therapeutic strategy (‘retrainment’) in patients with psychogenic tremor.MethodsTen patients with psychogenic tremor (5 women, mean age, 53.6 ± 12.8 years; mean disease duration 4.3 ± 2.7 years) were asked to participate in a pilot proof-of-concept study aimed at “retraining” their tremor frequency. Retrainment was facilitated by tactile and auditory external cueing and real-time visual feedback on a computer screen. The primary outcome measure was the Tremor subscale of the Rating Scale for Psychogenic Movement Disorders.ResultsTremor improved from 22.2 ± 13.39 to 4.3 ± 5.51 (p = 0.0019) at the end of retrainment. The benefits were maintained for at least 1 week and up to 6 months in 6 patients, with relapses occurring in 4 patients between 2 weeks and 6 months. Three subjects achieved tremor freedom.ConclusionsTremor retrainment may be an effective short-term treatment strategy in psychogenic tremor. Although blinded evaluations are not feasible, future studies should examine the long-term benefits of tremor retrainment as adjunctive to psychotherapy or specialized physical therapy.     

Tremor pattern differentiates drug-induced resting tremor from Parkinson disease

ObjectiveDAT-SPECT, is a well-established procedure for distinguishing drug-induced parkinsonism from Parkinson's disease (PD). We investigated the usefulness of blink reflex recovery cycle (BRrc) and of electromyographic parameters of resting tremor for the differentiation of patients with drug-induced parkinsonism with resting tremor (rDIP) from those with resting tremor due to PD.MethodsThis was a cross-sectional study. In 16 patients with rDIP and 18 patients with PD we analysed electrophysiological parameters (amplitude, duration, burst and pattern) of resting tremor. BRrc at interstimulus intervals (ISI) of 100, 150, 200, 300, 400, 500 and 750 msec was also analysed in patients with rDIP, patients with PD and healthy controls. All patients and controls underwent DAT-SPECT.ResultsRest tremor amplitude was higher in PD patients than in rDIP patients (p < 0.001), while frequency and burst duration were higher in rDIP than in PD (p < 0.001, p < 0.003, respectively). Resting tremor showed a synchronous pattern in all patients with rDIP, whereas it had an alternating pattern in all PD patients (p < 0.001). DAT-SPECT was normal in rDIP patients while it was markedly abnormal in patients with PD.ConclusionsIn the absence of DAT-SPECT, the pattern of resting tremor can be considered a useful investigation for differentiating rDIP from PD.     

The spiral axis as a clinical tool to distinguish essential tremor from dystonia cases

BackgroundTremor is a common feature of a variety of neurological disorders. In genetic studies of essential tremor (ET), investigators need to screen potential enrollees by mail or telephone to exclude those with other neurological conditions, especially dystonia. In clinical settings, the differentiation of ET and dystonia may also be very challenging. We hypothesized that the spiral axis, described below, is a useful screening tool to distinguish ET cases from dystonia cases.MethodsWe analyzed the hand-drawn spirals of 135 individuals enrolled in a genetics study at Columbia University Medical Center. Each of the four spirals was assessed for the presence of a single identifiable tremor orientation axis, and a spiral axis score (range = 0–4) [a single axis on all 4 spirals] was assigned to each enrollee.ResultsThere were 120 ET cases and 15 cases with dystonic tremor. Most (101/120, 84.2%) ET cases had an axis score ≥1 vs. only half (8/15, 53.3%) of the dystonia cases (p = 0.02). Receiver Operator Curve (ROC) analysis revealed that the use of a spiral axis score ≥2 as a cut off would exclude 60.0% of dystonia cases while including 67.5% of ET cases.ConclusionHandwritten spirals appear to have a single predominant axis in more ET than dystonia cases. The evaluation of this axis has moderate diagnostic validity as a screening tool to distinguish ET cases from those with dystonia. Although this study did not assess the utility of this tool in clinical practice settings, future studies should do so.     

Diabetes is associated with postural instability and gait difficulty in Parkinson disease

BackgroundComorbid diabetes may be associated with more severe motor impairment in Parkinson disease. In normal elderly individuals, diabetes is associated with parkinsonian features, including gait difficulty and rigidity, though not tremor. Whether diabetes contributes to increased motor dysfunction in Parkinson disease by exacerbating nigrostriatal dopaminergic denervation or through intensification of extranigral pathology is unknown.MethodsWe performed a case–control study (n = 39) involving 13 Parkinson disease subjects (age 66.4yrs ± 5.5; duration of disease 6.9yrs ± 4.4) with diabetes and 26 age, gender, and duration-of-disease-matched Parkinson disease controls without diabetes. All subjects underwent [¹¹C]dihydrotetrabenazine vesicular monoamine transporter type-2 positron emission tomography imaging to assess striatal dihydrotetrabenazine distribution volume ratio and Unified Parkinson disease rating scale motor examination to determine rigidity, bradykinesia, tremor, and postural instability and gait difficulty subscores. Magnetic resonance imaging scans were analyzed to assess leukoaraiosis burden.ResultsAfter controlling for nigrostriatal dopaminergic denervation, Parkinson disease subjects with diabetes displayed greater postural instability and gait difficulty subscores (t = 3.81, p = 0.0005). There were no differences in bradykinesia, rigidity, or tremor subscores between cases and controls. The association between diabetes and postural instability and gait difficulty persisted after controlling for comorbid hypertension and body mass index. Leukoaraiosis, distal vibratory sense, and levodopa dose equivalents did not differ significantly between cases and controls.ConclusionsDiabetes may contribute to postural instability and gait difficulty in Parkinson disease through mechanisms other than nigrostriatal dopaminergic denervation.     

Electrophysiological evaluation of tremors secondary to space occupying lesions and trauma: Correlation with nature and sites of lesions

BackgroundElectrophysiological evaluation of tremor secondary to intracranial space occupying lesions (SOL) and cranial trauma may provide information regarding pathophysiology of tremors.ObjectivesTo compare the electrophysiological characteristics of tremor secondary to SOL and trauma and to correlate tremor characteristics with sites of lesion, and types of SOL.MethodsMulti-channel tremor recording and MRI were performed in 18 patients with predominantly tremor secondary to SOL (F: M = 5:6; age ± SD: 26.6 ± 15.0 years) and following trauma (7 men; age: 27.3 ± 11.0 years).ResultsIn both groups, there was a wide range in the frequency of tremor (2.5–7.5 Hz in the SOL group and 2–7.5 Hz in the post-trauma group) and a strong inverse correlation of the frequency with the duration of EMG bursts (SOL group: r = 0.8, p = 0.004; post-trauma group: r = 0.9, p = 0.02). While all the patients with SOL had regular EMG bursts (synchronous – 54.6%, alternating – 27.3%, mixed – 18.2%), 85.7% of post-trauma patients had irregular EMG bursts (synchronous – 42.9%, alternating – 14.3%, mixed – 42.9%). In SOL group, those with predominantly intrinsic destructive lesions of brainstem, thalamus, or basal ganglia (n = 7) had a statistically significant lower mean frequency of tremor than those (n = 4) with either extrinsic or intrinsic compressive lesions (3.5 ± 0.9 Hz vs 6.7 ± 0.6 Hz; p = 0.0001). In the post-trauma group, the patients with additional lesions in thalamus or striatum, apart from white and grey matter lesions had lower mean tremor frequency (3.7 ± 1.0 Hz vs 6.1 ± 1.5 Hz; p = 0.05).ConclusionsThe electrophysiological characteristics of tremor secondary to SOL and trauma differ and correlate with the nature and sites of lesions. This information, which need to be validated in larger cohort of patients, may be useful in understanding the pathogenesis of tremor.