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Biomedical subjects

Y L Lo

Publications and source records attributed to Y L Lo.

At least 37 records · Page 2Linked to original sources
PubMed2004

Systematic correlation of transcranial magnetic stimulation and magnetic resonance imaging in cervical spondylotic myelopathy.

STUDY DESIGN: A prospective study over a 3.5-year period involving transcranial magnetic stimulation and magnetic resonance imaging. OBJECTIVES: To assess the correlation of transcranial magnetic stimulation and magnetic resonance imaging in cervical spondylotic myelopathy qualitatively and statistically. SUMMARY OF BACKGROUND DATA: Cervical spondylotic myelopathy presents with different degrees of cord compression, which can be assessed by magnetic resonance imaging. There are no large studies correlating transcranial magnetic stimulation and magnetic resonance imaging findings in this condition. METHODS: A total of 141 patients with a clinical diagnosis of cervical spondylotic myelopathy were prospectively studied over a 3.5-year period. They were classified into Groups 1 to 4 based on severity of cervical cord changes on magnetic resonance imaging. All had transcranial magnetic stimulation and central motor conduction time measurements within 2 months of the magnetic resonance imaging study. RESULTS: Twenty-eight, 49, 28, and 36 patients were classified into Groups 1 to 4, respectively. Mean upper limb and lower limb central motor conduction times correlated with the severity of magnetic resonance cord compression. The absence of central motor conduction time abnormalities correlated reliably with the absence of cervical cord impingement as in Group 1. Statistically significant right left difference in central motor conduction time in the lower limbs was seen between Groups 1 (no cord changes) and Group 2 (mild cord impingement). Eight other patients with diagnoses other than cervical spondylotic myelopathy all showed central motor conduction time abnormalities. The sensitivity and specificity for transcranial magnetic stimulation for differentiating the presence from absence of magnetic resonance imaging cord abnormality were 100% and 84.8%, respectively. CONCLUSIONS: Transcranial magnetic stimulation showed excellent correlation with magnetic resonance imaging findings and can be considered as an effective technique for screening patients for cervical cord abnormalities before magnetic resonance imaging in the clinical setting. The findings in this study have relevant implications in the pathophysiology, management, and health costs of cervical spondylotic myelopathy.

Adult↗
PubMed2004

Alpha-synuclein haplotypes implicated in risk of Parkinson's disease.

The authors examined four- and six-loci haplotype constructs (from five single nucleotide polymorphisms and three microsatellite regions) of the alpha-synuclein gene in patients with Parkinson's disease (PD) and controls in an ethnic Chinese population. Logistic regression analysis demonstrated an association of NACP-Rep1 (p = 0.002) and L478 (p < 0.0001) with risk of PD after correction for the effects of age, sex, and the other polymorphic loci. Specific four-loci and six-loci haplotypes were significantly associated with an increased or decreased risk of PD.

Adult↗
PubMed2004

Posterior antebrachial cutaneous nerve conduction studies in normal subjects.

OBJECTIVE: The posterior antebrachial cutaneous (PABC) nerve is a sensory nerve that branches out from the radial nerve at the level of the spiral groove. Thus it can be affected in a radial nerve lesion at or proximal to its origin in the spiral groove. However, there has been limited knowledge about the normal values of PABC nerve conduction studies. This study was done to determine these normal values. METHODS: Sixty-three healthy adults (23 males) with a mean age of 41.5+/-10.6 (range, 20-90) years were recruited with informed consent. A total of 126 nerves were studied. The nerve conduction studies were performed using a Dantec Counterpoint EMG machine (Dantec, Skovlunde, Denmark). RESULTS: The mean+/-standard deviation values for the onset as well as peak latency, conduction velocity, amplitude and side-to-side amplitude ratio were 2.07+/-0.16 (range, 1.80-2.60) ms, 2.35+/-0.15 (range, 2.05-2.90) ms, 58.21+/-4.29 (range, 46.15-66.67) m/s, 6.10+/-2.11 (range, 2.90-13.00) microV and 0.83+/-0.12 (range, 0.60-0.99), respectively. There was a significant correlation between the subject age and the PABC onset and peak latencies as well as the amplitudes. CONCLUSIONS: The PABC nerve is assessable for nerve conduction studies and these normal values may be useful in evaluation of patients with suspected radial nerve lesions.

Adult↗
PubMed2004

Overriding fifth finger: an unusual sign in lower brachial plexopathy.

Hand deformities are often useful clinical signs. To our knowledge, they have not been described in association with brachial plexus lesions. A 28-year-old female presented with sudden left shoulder pain and medial forearm parasthesia. Examination showed the left fifth finger adducting and flexing over the dorsal aspect of the fourth finger. Neurophysiological studies and MRI supported a brachial plexus lesion. The physical sign was not present 5 months post onset and the patient experienced near complete clinical improvement. The unusual physical sign occurred in association with neuralgic amyotrophy. Its occurrence can be explained in terms of transient patchy involvement of nerve fascicles in the brachial plexus.

Adult↗
PubMed2004

Intra-operative monitoring in scoliosis surgery with multi-pulse cortical stimuli and desflurane anesthesia.

STUDY DESIGN: Prospective, observational study. SETTING: Country General Hospital, Singapore. OBJECTIVE: Intraoperative monitoring (IOM) with motor-evoked potentials (MEPs) assesses the integrity of cortical spinal tracts during scoliosis surgery. MEPs are sensitive to the effects of inhalational anesthetic agents. We evaluate the use of desflurane in combination with multipulse cortical stimulation in this study. METHODS: In all, 10 consecutive neurologically normal subjects underwent scoliosis surgery with desflurane anesthesia (0.5 maximum alveolar concentration) and five pulse cortical stimulation (250 Hz) from two stimulators in parallel configuration, delivering a maximum intensity of 160 mA. RESULTS: Consistent MEPs were obtained from the abductor hallucis and tibialis anterior in nine of ten and five of five of subjects, respectively. Baseline coefficients of variations were below 16% for both muscles. CONCLUSION: This combination of anesthetic and stimulation protocols is efficacious for IOM during spinal cord surgery. Our findings support the use of desflurane for successful acquisition of MEPs during scoliois surgery as an alternative anesthetic regime.

Adolescent↗
PubMed2004

SUNCT syndrome in association with persistent Horner syndrome in a Chinese patient.

This is the first case report of a chinese patient with SUNCT (shortlasting, unilateral, neuralgiform headache attacks with conjunctival injection and tearing) presenting with persistent Horner's syndrome. She had episodic, brief, right periorbital pain in association with ipsilateral eye injection, lacrimation and rhinorrhea as well as persistent ipsilateral miosis and ptosis. She had partial response to a combination of indomethacin and carbamazepine therapy.

China↗
PubMed2004

Restless hand symptoms in carpal tunnel syndrome.

Carpal tunnel syndrome (CTS) is a nerve entrapment disorder, involving the median nerve when it passes the carpal tunnel at the wrist. Using a case-control methodology, 312 electrophysiologically confirmed CTS patients with mean age of 51.3+/-9.4 (27-74) years (81.7% women) and 100 controls with mean age of 50.4+/-9.2 (21-88) years (75% women) were examined utilising a questionnaire similar to the clinical diagnostic criteria of restless legs syndrome (RLS). Forty-four (14.1%) of the CTS patients have symptoms compatible with restless hand syndrome compared with none (0%) in the control group (p < 0.0001). The severity of CTS was not significantly associated with the motor restlessness. Our observations suggest that entrapment syndromes such as CTS can be associated with a form of restlessness in the hands, analogous to RLS.

Adult↗
PubMed2004

Acute ophthalmoparesis in the anti-GQ1b antibody syndrome: electrophysiological evidence of neuromuscular transmission defect in the orbicularis oculi.

OBJECTIVE: To prospectively study anti-GQ1b antibody positive cases of acute ophthalmoparesis (AO) clinically and electrophysiologically. METHODS: Nine consecutive cases presenting with predominantly acute ophthalmoplegia were assessed clinically and had stimulated single fibre electromyography (SFEMG) of the orbicularis oculi at presentation. All had magnetic resonance imaging brain scans and anti-GQ1b antibody titres determined. RESULTS: Four cases had elevated anti-GQ1b antibody titres and abnormal SFEMG studies, which improved in tandem with clinical recovery over three months. Five other anti-GQ1b antibody negative cases were diagnosed as diabetic related cranial neuropathy, idiopathic cranial neuropathy, ocular myasthenia gravis, and Tolosa-Hunt syndrome. All five cases showed complete recovery over a three month period. CONCLUSIONS: This study demonstrated electrophysiologically the dynamic improvement of neuromuscular transmission of anti-GQ1b antibody positive cases of AO, in tandem with clinical recovery. SFEMG is of value in differentiating weakness due to neuromuscular transmission defect from neuropathy in these clinical situations.

Acute Disease↗
PubMed2004

Characteristics and acute rehabilitation of Guillain-Barré syndrome in Singapore.

INTRODUCTION: The objectives of this study are to describe the demographics, clinical characteristics, complications and functional outcomes in patients with Guillain-Barr é syndrome (GBS) or the Miller-Fisher syndrome (MFS) variant admitted to our institution. We also aim to identify prognostic outcome indicators. MATERIALS AND METHODS: A retrospective review of the case records of all patients discharged from our hospital with a diagnosis of GBS or MFS over a 2- year period was performed. The clinical characteristics charted included the time of symptom onset to nadir. The Modified Barthel Index (MBI) and Expanded Grading Scale (EGS) for GBS were the functional outcome measures used. RESULTS: Thirty-one cases were reviewed and 8 (25.8 %) had the MFS variant. Twenty-two (71 %) patients were male, with a mean age of 42.3 years. Weakness and numbness (74 %) were the most common initial symptoms; 9 (29 %) patients were paraparetic and 7 (22.6 %) were tetraparetic. Ten (32.3 %) patients had respiratory involvement and 8 (25.8 %) had urinary retention. Intravenous immunoglobulin (IVIG) was prescribed in 13 (41.9 %) patients. The mean duration to disease nadir was 8.1 days. The mean MBI scores at nadir and discharge were 54.7 and 77.3, respectively, and this gain was highly significant (P <0.01). The majority (84 %) of patients were employed at admission and although most returned to work, 63 % (17/27) of the patients had residual symptoms or signs 3 months after discharge. CONCLUSION: The clinical characteristics and complication frequency closely follows that previously described in Western populations, although our cohort was younger and had a higher proportion of the MFS variant. Predictors of a poorer functional outcome include a high EGS score at nadir, tetraparesis, respiratory involvement, urinary retention and the need for nasogastric enteral feeding. Patients who had MFS or received IVIG had greater functional gains. Good functional outcomes occurred in a large majority of patients.

Adult↗
PubMed2003

Cortical excitability changes associated with musical tasks: a transcranial magnetic stimulation study in humans.

Neuroimaging studies have suggested differences in cortical activation in human vocalization and musical tasks. However, functional neurophysiological evidence on cortical excitability changes is lacking. We utilized transcranial magnetic stimulation to demonstrate changes in cortical excitability during overt humming and singing tasks. The findings complement those from neuroimaging and support the existence of separate bilateral deep-seated neural networks, as distinct from those for vocalization.

Adult↗
PubMed2003

Acupuncture and the modulation of cortical excitability.

Although acupuncture is increasingly utilized for medical therapy, its mechanism of action remains uncertain. We used transcranial magnetic stimulation to demonstrate lateralized effects of motor cortex excitability with this technique. Right-sided reduction in motor cortex excitability and a tendency to the opposite effect on the left side was seen with acupuncture. Sham needle insertions did not result in significant changes of motor cortex excitability. These findings provide new neurophysiological evidence of cortical excitability modulation complementary to findings derived from functional neuroimaging studies.

Acupuncture Therapy↗
PubMed2003

Increased cortical excitability in human deception.

Deception is a cognitive process in humans and animals which is not well understood. Most studies on lie detection have focused on emotional components associated with deception. We employed transcranial magnetic stimulation of the motor cortex in conjunction with a constrained question answer protocol for the first time to show increased cortical excitability in generating deceptive responses, in contrast with truthful responses. This may be due to increased cognitive activity in the motor and premotor connections. Our findings corroborate functional imaging studies and may have future implications in evaluating lie detection.

Adult↗
PubMed2003

Statin therapy and small fibre neuropathy: a serial electrophysiological study.

We describe three patients who developed small fibre neuropathy after 1 month of statin therapy with clinical resolution upon prompt drug withdrawal. All patients showed abnormal sympathetic skin responses (SSR) in comparison with controls. SSRs returned to normal in tandem with clinical improvement. One patient redeveloped small and large fibre neuropathy when the similar drug was readministered. The SSR is of value in the electrophysiological assessment and follow-up of statin-related small fibre neuropathy.

Anticholesteremic Agents↗
PubMed2003

Decrement in area of muscle responses to repetitive nerve stimulation.

Measurement of the decremental muscle response to repetitive nerve stimulation (RNS) has low yields for the diagnosis of neuromuscular transmission defects compared with single fiber electromyography (SFEMG). We compared area and amplitude of muscle responses to RNS in 87 patients and 30 controls, using SFEMG as the reference standard. Decrement of response area provided additional diagnostic yields of 5.3% to 30% depending on the muscle examined and disease severity, and is recommended as a diagnostic adjunct to measurement of amplitude decrement during RNS.

Action Potentials↗
PubMed2003

Corticobulbar dysfunction in the Miller Fisher syndrome.

The Miller Fisher syndrome is an immunologically mediated condition with minimal motor manifestations. We describe a case showing mild reversible dysarthria and weak lingual movements with complete recovery over 2 months. Transcranial magnetic stimulation studies give an evidence of a reversible corticobulbar conduction abnormality which resolved with clinical improvement.

Adult↗
PubMed2003

Traumatic atypical Brown-Sequard syndrome: case report and literature review.

A man was kicked on the neck, 10 days after which he noted right-sided numbness. Clinically, he had diminished deep tendon reflexes over the left upper limb, absent left superficial abdominal reflexes, a left extensor plantar response, mild left hemiparesis, diminished pinprick, temperature and vibratory sensation up to the right T(4-5) dermatome and diminished proprioceptive sensation in the right upper and lower limbs. Cervicothoracic magnetic resonance imaging (MRI) revealed a left C(6-7) posterolateral disc prolapse with indentation and oedema of the cord at the same level. He was given intravenous dexamethasone, with mild resolution of his motor but not his sensory symptoms. Transcranial magnetic stimulation and evoked potentials performed 3 days later were unremarkable. He was discharged soon after, preferring to seek traditional therapy in his country. We attempt to explain the anatomical basis for his clinical signs, review the literature for similar cases, and examine the usefulness of available treatment and investigations.

Adult↗