Szu-Chia Lai

The effect of continuous theta burst stimulation over premotor cortex on circuits in primary motor cortex and spinal cord

OBJECTIVE To understand the effect of continuous theta burst stimulation (cTBS) given to the premotor area, we studied the circuits within the primary motor cortex and spinal cord after cTBS over the dorsal premotor area (PMd). METHODS Three sets of parameters, including corticospinal excitability, short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) and forearm reciprocal inhibition (RI) were tested. RESULTS Paralleling the effects of cTBS applied directly to the primary motor cortex, cTBS over the left PMd suppressed corticospinal excitability as measured by the change in the size of MEPs evoked by single pulse TMS over primary motor cortex. Premotor cTBS appeared to have a longer lasting, but no more powerful effect on corticospinal excitability than motor cTBS, however, unlike motor cTBS it had no effect on SICI or ICF. Finally, although premotor cTBS had no effect on spinal H-reflexes, it did reduce the third phase of RI between forearm extensor and flexor muscles. CONCLUSIONS Premotor cTBS is a quick and useful way of modulating excitability in cortical and possibly subcortical motor circuits. SIGNIFICANCE Premotor cTBS can be used as an alternative to regular rTMS to evaluate cortical function, motor behaviours and the response to disease therapy.

Contribution of glucocerebrosidase mutation in a large cohort of sporadic Parkinson’s disease in Taiwan

Background and purpose:  The association between glucocerebrosidase (GBA) mutations and Parkinson’s disease (PD) is attracting increased attention worldwide. In patients of Chinese ethnicity, other than the common L444P mutation, a few mutations have been reported. However, the contribution of GBA to PD can be answered only by a thorough investigation of its mutations in a unique large population.

Modulation of the Disturbed Motor Network in Dystonia by Multisession Suppression of Premotor Cortex

Daily sessions of therapeutic transcranial brain stimulation are thought to prolong or amplify the effect of a single intervention. Here we show in patients with focal hand dystonia that additional, new effects build up progressively over time, making it difficult to predict the effect of long term interventions from shorter treatment sessions. In a sham-controlled study, real or sham continuous theta burst stimulation (cTBS) was given once daily for five consecutive days to dorsolateral premotor cortex (PMd). Five days of real, but not sham, premotor cTBS improved intracortical inhibition in primary motor cortex (M1) to a similar extent on day 1 and day 5. However 5 days of cTBS were required to restore the abnormal PMd-M1 interactions observed on day 1. Similarly, excessive M1 plasticity seen at baseline was also significantly reduced by five days of real premotor cTBS. There was only a marginal benefit on writing. The results show that additional, new effects, at sites distant from the point of stimulation, build up progressively over time, making it difficult to predict the effect of long term interventions from shorter treatment sessions. The results indicate that it may take many days of therapeutic intervention to rebalance activity in a complex network.

Abnormal cortical excitability with preserved brainstem and spinal reflexes in sialidosis type I.

OBJECTIVE To examine neurophysiological evidence of functional involvement of the brainstem and spinal cord and motor cortical excitability in sialidosis type I, a rare inherited neurodegenerative disorder caused by mutations in the NEU1 gene. METHODS We investigated particular pathways in the brainstem, spinal cord and motor cortex in 12 genetically proven cases of sialidosis type I by assessing blink reflex recovery cycle (BR), spinal reciprocal inhibition (RI), input-output curves (I/O), short interval intracortical inhibition (SICI), intracortical facilitation (ICF) and silent period (SP). RESULTS The BR and RI were normal. The slope of I/O was significantly increased, and SICI and the duration of SP were reduced in sialidosis patients. CONCLUSIONS Despite reports of pathology involving brainstem and anterior horn neurones, there were no obvious abnormalities in spinal and brainstem reflexes in the present patients, suggesting that the major clinical effects may be caused by changes at a level above the brainstem. SIGNIFICANCE For the first time, the integrity of certain brainstem and spinal cord reflexes in addition to motor cortical facilitatory and inhibitory circuits has been assessed in genetically proven type I sialidosis. This provides new data to aid in understanding of the pathophysiology of motor system dysfunction in this condition.

Imaging early-stage corticobasal degeneration with [99mTc]TRODAT-1 SPET

AimThe aim of this study was to investigate the nigrostriatal dopaminergic function in patients with corticobasal degeneration (CBD) using [2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo[3.2.1]oct-2-yl]methyl](2-mercaptoethyl)amino]ethyl]amino]ethanethiolato(3-)-N2,N2′,S2,S2′]oxo-[1R-(exo-exo)]-[99mTc]technetium ([99mTc]TRODAT-1) brain single-photon emission tomography (SPET). MethodsFive patients with probable CBD, 10 age- and duration-matched patients with idiopathic Parkinsons disease (IPD) and 10 age-matched healthy volunteers completed the SPET study. The images were obtained 4 h after intravenous injection of 925 MBq of [99mTc]TRODAT-1. Using a magnetic resonance imaging atlas of the striatum, the ratios of specific striatal binding to non-specific occipital binding were calculated. ResultsClinical analysis showed that the CBD patients obtained significantly higher scores on the Unified Parkinsons Disease Rating Scale and a significantly worse score for activities of daily living. In the CBD and IPD groups, striatum−occipital/occipital, caudate nucleus−occipital/occipital and putamen−occipital/occipital ratios decreased significantly relative to those of healthy subjects. No statistical difference could be found between the CBD and IPD groups for these ratios, although relatively even, decreased uptakes in the caudate nucleus and putamen were found in the CBD group. On further analysis of the index of binding reduction, the differences between the caudate nucleus and putamen were significantly lower in the CBD group than in the IPD group. The striatal uptake of [99mTc]TRODAT-1 showed a distinct asymmetry in both the CBD and IPD patients. ConclusionFrom this study, it can be concluded that early-stage CBD patients have a worse performance and more difficulties with daily activities than IPD patients. CBD patients demonstrated essentially similar patterns of [99mTc]TRODAT-1 binding as those with IPD. However, there was relatively more homogeneous involvement of the caudate nucleus and putamen in the CBD patients. This provides information about the differences between these patients in the early stages.

Large SGCE deletion contributes to Taiwanese myoclonus-dystonia syndrome.

We report three novel deletions of the SGCE gene in three families with myoclonus-dystonia (M-D) syndrome in Taiwan. Their clinical characteristics included: early onset, dominant myoclonus and dystonia in the neck, trunk and upper limbs. By direct sequencing of the SGCE gene coding regions, we identified a small heterozygous deletion (c.842delA) in exon 7 of the three sibs and asymptomatic father in the first family and an eight-base heterozygous deletion (c.524_531del) in exon 5 of the mother and a daughter in the second family. Using multiple ligation-dependent probe amplification (MLPA), a large heterozygous deletion of 2-11 exons was identified in the father and a son in the third family which was undetected by initial sequencing. It is the largest intragenic deletion ever reported. In conclusion, we have identified three novel mutations of SGCE in the respective three M-D families. The large deletion was responsible for one third of these M-D families which might implicate an important contribution to Taiwanese M-D syndrome. We suggest that the contribution of large deletion should be further verified in a large cohort of patients with M-D syndrome in Han Chinese.

Neuronal intranuclear inclusion disease: Two cases of dopa-responsive juvenile parkinsonism with drug-induced dyskinesia†

There are very few conditions that present with dopa‐responsive juvenile parkinsonism. We present two such children with neuronal intranuclear inclusion disease (NIID) who had an initial good levodopa response that was soon complicated by disabling dopa‐induced dyskinesia. One child was diagnosed by rectal biopsy in life, and the other diagnosis was confirmed at postmortem. In this patient, dopamine transporter imaging showed severely decreased binding of the radiotracer in the striatum on both sides. Bilateral subthalamic deep brain stimulation in this patient produced initial improvement, but this was not sustained. Both patients died within 10 years of symptom onset. As well as levodopa responsiveness with rapid onset of dyskinesia, clues to the diagnosis of NIID in patients presenting with parkinsonism include the presence of gaze‐evoked nystagmus, early onset dysarthria and dysphagia and oculogyric crises. Differential diagnosis of clinical symptoms and neuropathological findings are discussed including the approach to rectal biopsy for early diagnosis.

Asymmetric Involvement in Sporadic Creutzfeldt-Jakob Disease: Clinical, Brain Imaging, and Electroencephalographic Studies

Objective: To ascertain the characteristics of patients with sporadic Creutzfeldt-Jakob disease (CJD) and to determine the findings of electroencephalography (EEG) and brain magnetic resonance imaging (MRI). Methods: We pooled patients at a hospital from 2000 to 2008, and classified them according to WHO diagnostic criteria as having probable or possible CJD. We retrospectively analyzed their clinical manifestations, brain MRI, and EEG findings to evaluate correlations among them. Results: In this study, 12 probable and 4 possible CJD patients were identified. Ten patients with probable CJD had asymmetric manifestations with hemiparesis, focal myoclonus, dystonia or apraxia; 9 had clinical manifestations mimicking the corticobasal syndrome. In contrast, neurological examinations did not show asymmetric signs in 4 patients with possible CJD. EEG showed a typical periodic sharp wave complex (PSWC) in 12 patients with probable CJD; most of them had bright signal intensity on diffusion-weighted imaging of the cortex and/or basal ganglia. There was a high tendency for asymmetric clinical manifestations that correlated with the presentation of PSWC and cortical lesions observed on the brain MRI scan. Conclusions: Our study indicates that asymmetric extrapyramidal symptoms/signs, in clinical features with characteristic abnormalities on MRI and EEG findings, might contribute to early diagnosis of sporadic CJD.

Clinical and genetic analysis of Taiwanese patients with hereditary spastic paraplegia type 5.

Spastic paraplegia type 5 (SPG5) is an autosomal recessive (AR) hereditary spastic paraplegia (HSP) associated with pure or complicated phenotypes. This study aimed to screen SPG5 in Taiwanese HSP patients.

Cortical damage in the posterior visual pathway in patients with sialidosis type 1

In order to identify the cortical changes in patients with Sialidosis type 1, diffusion tensor imaging and resting state fMRI were acquired from 11 patients and 11 sex/age matched normal controls after clinical evaluations. The neuroimages from each participant were normalized and parcellated according to the Automatic Anatomical Labeling. Both the mean diffusivity and the corresponding functional connectivity were calculated from each cortical region. The white matter tract integrity was examined. The difference between patients and controls was examined using Student’s t-test and between patients with either homozygous or heterozygous mutations by Mann–Whitney U test, both at a threshold of 0.05. Increased mean diffusivity throughout the brain can be noticed in the patients, together with a compromised white matter tracts integrity. The most severely affected cortical regions are in the occipital lobe. Decreased functional connectivity was from the temporal and occipital lobes to the hippocampus and parahippocampus. In contrast, connectivity from thalamus was enhanced. Diffused cortical atrophy with posterior focal lesions was noticed. We concluded that MRI observed functional changes in the posterior cortical pathways in the patients with Sialidosis. The observation might be related to the cortical blindness due to an altered neural network and a compromised visual pathway in the patients.