Petra Schwingenschuh

Distinguishing SWEDDs Patients with Asymmetric Resting Tremor from Parkinson's Disease: A Clinical and Electrophysiological Study

Approximately 10% of patients diagnosed clinically with early Parkinsons disease (PD) have normal dopaminergic functional imaging (Scans Without Evidence of Dopaminergic Deficit [SWEDDs]). An important subgroup of SWEDDs are those with asymmetric rest tremor resembling parkinsonian tremor. Clinical and pathophysiological features which could help to distinguish SWEDDs from PD have not been explored. We therefore studied clinical details including non‐motor symptoms in 25 tremulous SWEDDs patients in comparison to 25 tremor‐dominant PD patients. Blinded video rating was used to compare examination findings. Electrophysiological tremor parameters and also response to a cortical plasticity protocol using paired associative stimulation (PAS) was studied in 9 patients with SWEDDs, 9 with tremor‐dominant PD (with abnormal dopamine transporter single photon emission computed tomography findings), 8 with segmental dystonia, and 8 with essential tremor (ET). Despite clinical overlap, lack of true bradykinesia, presence of dystonia, and head tremor favored a diagnosis of SWEDDs, whereas re‐emergent tremor, true fatiguing or decrement, good response to dopaminergic drugs, and presence of non‐motor symptoms favored PD. A single tremor parameter could not differentiate between groups, but the combination of re‐emergent tremor and highest tremor amplitude at rest was characteristic of PD tremor. SWEDDs and segmental dystonia patients exhibited an abnormal exaggerated response to the PAS protocol, in contrast to a subnormal response in PD and a normal response in ET. We conclude that despite clinical overlap, there are features that can help to distinguish between PD and SWEDDs which may be useful in clinical practice. The underlying pathophysiology of SWEDDs differs from PD but has similarities with primary dystonia.

Early-onset L-dopa-responsive Parkinsonism with pyramidal signs due to ATP13A2, PLA2G6, FBXO7 and Spatacsin mutations

Seven autosomal recessive genes associated with juvenile and young‐onset Levodopa‐responsive parkinsonism have been identified. Mutations in PRKN, DJ‐1, and PINK1 are associated with a rather pure parkinsonian phenotype, and have a more benign course with sustained treatment response and absence of dementia. On the other hand, Kufor‐Rakeb syndrome has additional signs, which distinguish it clearly from Parkinsons disease including supranuclear vertical gaze palsy, myoclonic jerks, pyramidal signs, and cognitive impairment. Neurodegeneration with brain iron accumulation type I (Hallervorden‐Spatz syndrome) due to mutations in PANK2 gene may share similar features with Kufor‐Rakeb syndrome. Mutations in three other genes, PLA2G6 (PARK14), FBXO7 (PARK15), and Spatacsin (SPG11) also produce clinical similar phenotypes in that they presented with rapidly progressive parkinsonism, initially responsive to Levodopa treatment but later, developed additional features including cognitive decline and loss of Levodopa responsiveness. Here, using homozygosity mapping and sequence analysis in families with complex parkinsonisms, we identified genetic defects in the ATP13A2 (1 family), PLA2G6 (1 family) FBXO7 (2 families), and SPG11 (1 family). The genetic heterogeneity was surprising given their initially common clinical features. On careful review, we found the FBXO7 cases to have a phenotype more similar to PRKN gene associated parkinsonism. The ATP13A2 and PLA2G6 cases were more seriously disabled with additional swallowing problems, dystonic features, severe in some, and usually pyramidal involvement including pyramidal weakness. These data suggest that these four genes account for many cases of Levodopa responsive parkinsonism with pyramidal signs cases formerly categorized clinically as pallido‐pyramidal syndrome.

Long‐term antidyskinetic efficacy of amantadine in Parkinson's disease

Several randomized placebo‐controlled trials have consistently shown antidyskinetic effects of amantadine in levodopa treated patients with advanced Parkinsons disease (PD). However, all of these were of short duration and there have been claims that the effect of amantadine on levodopa induced dyskinesias (LIDs) wear off after about 9 months of treatment. This randomized placebo‐controlled parallel‐group study was performed to assess the long‐term antidyskinetic effect of amantadine in 32 PD patients, who after having been on stable amantadine therapy for LID over at least one year‐ were switched in a double blind manner to amantadine or placebo and followed for 3 weeks. Dyskinesia duration and intensity were assessed by UPDRS IV items 32 and 33 as well as by patients diaries. The primary outcome was the score change of UPDRS IV items 32 + 33 between baseline and 3 weeks after treatment as well as the between treatment group comparison of the score change of UPDRS IV items 32 + 33. There was a significant increase of UPDRS IV items 32 + 33 in patients treated with placebo from 3.06 (95% CI, 2.1–4.03) at baseline to 4.28 (95% CI, 3.1–5.4) at three‐week follow‐up (P = 0.02) compared with no significant change between baseline 3.2 (95% CI, 2.1–4.4) to follow‐up 3.6 (95% CI, 2.3–4.8) in patients staying on amantadine. These findings argue for long‐term antidyskinetic efficacy of amantadine in PD patients with LIDs.

Autosomal-dominant GTPCH1-deficient DRD: clinical characteristics and long-term outcome of 34 patients

Background: An autosomal dominantly inherited defect in the GCH1 gene that encodes guanosine triphosphate cyclohydrolase 1 (GTPCH1) is the most common cause of dopa-responsive dystonia (DRD). A classic phenotype of young-onset lower-limb dystonia, diurnal fluctuations and excellent response to levodopa has been well recognised in association with GCH1 mutations, and rare atypical presentations have been reported. However, a number of clinical issues remain unresolved including phenotypic variability, long-term response to levodopa and associated non-motor symptoms, and there are limited data on long-term follow-up of genetically proven cases. Methods: A detailed clinical evaluation of 34 patients (19 women, 15 men), with confirmed mutations in the GCH1 gene, is presented. Results and conclusions: The classic phenotype was most frequent (n = 23), with female predominance (F:M = 16:7), and early onset (mean 4.5 years) with involvement of legs. However, a surprisingly large number of patients developed craniocervical dystonia, with spasmodic dysphonia being the predominant symptom in two subjects. A subset of patients, mainly men, presented with either a young-onset (mean 6.8 years) mild DRD variant not requiring treatment (n = 4), or with an adult-onset (mean 37 years) Parkinson disease-like phenotype (n = 4). Two siblings were severely affected with early hypotonia and delay in motor development, associated with compound heterozygous GCH1 gene mutations. The study also describes a number of supplementary features including restless-legs-like symptoms, influence of female sex hormones, predominance of tremor or parkinsonism in adult-onset cases, initial reverse reaction to levodopa, recurrent episodes of depressive disorder and specific levodopa-resistant symptoms (writer’s cramp, dysphonia, truncal dystonia). Levodopa was used effectively and safely in 20 pregnancies, and did not cause any fetal abnormalities.

Tremor—Some Controversial Aspects

The commonest cause of pathological tremor is essential tremor (ET). However, it has proved difficult to identify genetic mutations causing ET, particularly because other causes of tremor continue to be misdiagnosed as ET. Whether subjects with dystonia or Parkinsons disease (PD) carry an increased genetic risk of developing ET, or vice versa, is controversial. In addition, the notion of a separate disorder of benign tremulous parkinsonism (BTP) has been debated. This article gives a selective viewpoint on some areas of uncertainty and controversy in tremor.

Psychogenic movement disorders in children: A report of 15 cases and a review of the literature

Data on psychogenic movement disorders (PMD) in children are scarce, with most existing literature relating to adults only. We report 15 cases with the aim of highlighting the clinical characteristics, risk factors, comorbidity, treatment, outcome, and prognosis of PMD in children. Only 13% of cases had onset before age 10, with the mean age at onset being 12.3 years. Females were predominantly affected (F:M = 4:1). The most common types of movement disorders seen were dystonia (47%), tremor (40%), and gait disorders (13%). Multiple hyperkinetic phenomenologies were observed in many cases. Abrupt onset and precipitation by minor injuries, and stressful life events were commonly reported. Clinical clues on examination suggesting a psychogenic origin were similar to those identified in adults. A distinct feature of PMD in children was the predominant involvement of the dominant limb. The underlying psychiatric diagnosis was conversion disorder in the majority of cases. Time from symptom onset until diagnosis of a PMD varied broadly (between 2 weeks and 5 years). Treatment with cognitive and behavioral therapy and rehabilitation by a multidisciplinary team led to improvement in most cases. However, treatment was much more effective in children with a short time from symptom onset to diagnosis and treatment.

THAP1 mutations (DYT6) are an additional cause of early-onset dystonia

Background: The clinical phenotype of DYT6 consists mainly of primary craniocervical dystonia. Recently, the THAP1 gene was identified as the cause of DYT6, where a total of 13 mutations have been identified in Amish-Mennonite and European families. Methods: We sequenced the THAP1 gene in a series of 362 British, genetically undetermined, primary dystonia patients (78 with focal, 186 with segmental, and 98 with generalized dystonia) and in 28 dystonia-manifesting DYT1 patients and 176 normal control individuals. Results: Nine coding mutations were identified in the THAP1 gene. Two were small deletions, 2 were nonsense, and 5 were missense. Eight mutations were heterozygous, and 1 was homozygous. The main clinical presentation of cases with THAP1 mutations was early-onset (<30 years) dystonia in the craniocervical region or the limbs (8 of 9 patients). There was phenotypic variability with laryngeal or oromandibular dystonia present in 3 cases. Four of 9 THAP1 cases developed generalized dystonia. Conclusions: The number of THAP1 mutations has been significantly expanded, indicating an uncommon but important cause of dystonia. Coding mutations account for 9 of 362 dystonia cases, indicating a mutation frequency of 2.5% of dystonia cases in the population that we have screened. The majority of cases reported here with THAP1 mutations had craniocervical- or limb-onset segmental dystonia, but we also identified 1 homozygous THAP1 mutation, associated initially with writers dystonia and then developing segmental dystonia. Three of our patients had a nonsense or frameshift THAP1 mutation and the clinical features of laryngeal or oromandibular dystonia. These data suggest that early-onset dystonia that includes the involvement of the larynx or face is frequently associated with THAP1 mutations.

Moving toward "laboratory-supported" criteria for psychogenic tremor.

A confident clinical diagnosis of psychogenic tremor is often possible, but, in some cases, a “laboratory‐supported” level of certainty would aid in early positive diagnosis. Various electrophysiological tests have been suggested to identify patients with psychogenic tremor, but their diagnostic reliability has never been assessed “head to head” nor compared to forms of organic tremor other than essential tremor or PD. We compared baseline tremor characteristics (e.g., frequency and amplitude) as well as electrophysiological tests previously reported to distinguish psychogenic and organic tremor in a cohort of 13 patients with psychogenic tremor and 25 patients with organic tremor, the latter including PD, essential‐, dystonic‐, and neuropathic tremors. We assessed between‐group differences and calculated sensitivity and specificity for each test. A number of tests, including entrainment or frequency changes with tapping, pause of tremor during contralateral ballistic movements, increase in tremor amplitude with loading, presence of coherence, and tonic coactivation at tremor onset, revealed significant differences on a group level, but there was no single test with adequate sensitivity and specificity for separating the groups (33%–77% and 84%–100%, respectively). However, a combination of electrophysiological tests was able to distinguish psychogenic and organic tremor with excellent sensitivity and specificity. A laboratory‐supported level of diagnostic certainty in psychogenic tremor is likely to require a battery of electrophysiological tests to provide sufficient specificity and sensitivity. Our data suggest such a battery that, if supported in a prospective study, may form the basis of laboratory‐supported criteria for the diagnosis of psychogenic tremor.

Olfaction in patients with suspected Parkinsonism and scans without evidence of dopaminergic deficit (SWEDDs)

Background: Positron emission tomography and single photon emission computed tomography scanning have 87–94% sensitivity and 80–100% specificity to differentiate patients with Parkinson’s disease (PD) from control subjects and patients with essential (ET) or atypical tremor. More than 10% of patients diagnosed as early PD can have scans without evidence of dopaminergic deficiency (SWEDDs). This study investigated whether smell tests can help identify possible cases with SWEDDs. Methods: The 40 item University of Pennsylvania Smell Test (UPSIT) was used to evaluate the sense of smell in 21 SWEDDs patients. Twenty-six ET patients, 16 patients with a diagnosis of idiopathic adult onset dystonia (D), 191 non-demented PD patients and 136 control subjects were also tested. Multiple regression analyses were used to compare the mean UPSIT score in the SWEDDs group with the other four groups (ET, D, PD and controls) after adjusting for the effects of relevant covariates. Results: The mean UPSIT score for the SWEDDs group was greater than in the PD group (p<0.001) and not different from the mean UPSIT in the control (p = 0.7), ET (p = 0.4) or D (p = 0.9) groups. Smell tests indicated a high probability of PD in only 23.8% of SWEDDs as opposed to 85.3% of PD patients. Conclusions: In a patient with suspected PD, a high PD probability on smell testing favours the diagnosis of PD, and a low PD probability strengthens the indication for dopamine transporter imaging.

Metabolic Syndrome, Brain Magnetic Resonance Imaging, and Cognition

OBJECTIVE We explored cognitive impairment in metabolic syndrome in relation to brain magnetic resonance imaging (MRI) findings. RESEARCH DESIGN AND METHODS We studied 819 participants free of clinical stroke and dementia of the population-based Austrian Stroke Prevention Study who had undergone brain MRI, neuropsychological testing, and a risk factor assessment relevant to National Cholesterol Education Program Adult Treatment Panel III criteria–defined metabolic syndrome. High-sensitivity C-reactive protein (hs-CRP) was also determined. RESULTS Of 819 subjects, 232 (28.3%) had metabolic syndrome. They performed worse than those without metabolic syndrome on cognitive tests assessing memory and executive functioning after adjustment for possible confounders. Stratification by sex demonstrated that metabolic syndrome was related to cognitive dysfunction in men but not in women. Only in men was an increasing number of metabolic syndrome components associated with worse cognitive performance. MRI showed no significant differences in focal ischemic lesions and brain volume between subjects with and without metabolic syndrome, and MRI abnormalities failed to explain impaired cognition. Cognitive performance was most affected in male subjects with metabolic syndrome who also had high hs-CRP levels. CONCLUSIONS Metabolic syndrome exerts detrimental effects on memory and executive functioning in community-dwelling subjects who have not had a clinical stroke or do not have dementia. Men are more affected than women, particularly if they have high inflammatory markers. MRI-detected brain abnormalities do not play a crucial role in these relationships.