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Yew-Long Lo

Publications and source records attributed to Yew-Long Lo.

9 recordsLinked to original sources
PubMed2007

Impaired motor imagery in patients with essential tremor: a case control study.

Motor imagery (MI), which refers to the process of mental representation of movements, has not been studied in patients with essential tremor (ET). We investigated the presence of impaired MI in ET patients compared with healthy controls. A group of drug-naive and nondemented ET patients and age-matched controls were studied using transcranial magnetic stimulation, while they were specifically instructed to try and imagine themselves performing two motor tasks. The various clinical and electrophysiological variables were evaluated and compared. Repeated measures ANOVA demonstrated a significant difference between ET patients and controls with respect to mean motor-evoked potential (MEP) amplitudes (F(1,38) = 31.92, P < 0.005) during MI. The process of MI effectively facilitated MEP amplitude in controls but not in ET patients, regardless of side of stimulation or motor tasks. We provide evidence to demonstrate impairment of MI in a group of ET patients compared with healthy controls. The basis for this novel finding is unclear, and further studies are warranted to determine whether it is related to cerebellar or motor cortical dysfunction.

Adult↗
PubMed2006

Isolated facial myorhythmia.

Myorhythmia, characterized by relatively rhythmic and regular 1- to 3-Hz muscle contractions, may involve isolated limbs or in combination with other various body regions. Isolated facial myorhythmia is rare. We highlight the clinical and electrophysiologic features of a unique case of isolated facial myorhythmia. Extensive investigations did not reveal any conclusive secondary causes. Dopaminergic dysfunction could be one of the etio-pathologic factors. However, the pathological basis why the facial region was selectively involved in our patient is unclear. Early recognition of the symptoms and signs would facilitate investigations for an underlying cause.

Aged↗
PubMed2006

Intraoperative motor-evoked potential monitoring in scoliosis surgery: comparison of desflurane/nitrous oxide with propofol total intravenous anesthetic regimens.

STUDY DESIGN: A prospective, randomized study in a large general hospital setting. BACKGROUND: During spinal surgery, monitoring motor-evoked potentials (MEPs) is a means of assessing the intraoperative integrity of corticospinal pathways. However, MEPs are known to be sensitive to the effects of anesthetic agents. OBJECTIVE: To compare the use of desflurane or total intravenous anesthetic regimens (TIVA) with multipulse cortical stimulation for intraoperative monitoring (IOM). METHODS: Twenty consecutive patients (10 in each arm) undergoing scoliosis correction surgery were randomly assigned to 2 equal groups receiving desflurane or TIVA. Inhalational anesthesia was maintained using 66% nitrous oxide in oxygen and a mean end-tidal desflurane concentration of 3.4%. For TIVA, continuous intravenous infusion of propofol was used. For analgesia, fentanyl and morphine were given when required for both groups. Cortical stimulation was achieved with 2 bipolar direct current stimulators connected in parallel by jumper cables. Five equivalent pulses 0.5 ms in duration at 4 ms intervals were delivered at C1C2 positions. MEP recordings were made in the abductor hallucis (AH) and tibialis anterior (TA) with needle electrodes. RESULTS: Reproducible MEPs were obtained throughout the operation in all 20 cases, with up to 80 mA per stimulator. Before insertion of pedicle screws, mean MEP amplitudes (SD) obtained were 85 (19) and 21.7 (10.8) mV for AH and TA, respectively, using desflurane. With TIVA, amplitudes were 56.7 (28.4) and 59.1 (24.5) mV, respectively. Both muscle MEP amplitudes were significantly different using different anesthetic regimens (P < 0.05 for all). AH MEP amplitudes obtained with desflurane were significantly larger than TA amplitudes (P < 0.0001). No complications were reported intraoperatively and postoperatively. CONCLUSIONS: This is the first study comparing the use of desflurane and TIVA showing that both anesthetic regimens allowed successful intraoperative monitoring useage throughout the procedures. For MEP recording, the AH was the preferred muscle with a desflurane anesthetic regimen.

Adolescent↗
PubMed2005

Pectoral nerve conduction studies: technique in healthy subjects and evaluation of brachial plexopathy.

OBJECTIVE: To define the optimal nerve conduction study (NCS) technique of the pectoral nerves and evaluate its clinical utility. DESIGN: Prospective electrophysiologic study with healthy controls. SETTING: Electrophysiologic laboratory in a large general hospital. PARTICIPANTS: Thirty healthy controls and 10 patients with cervical root or brachial plexus pathologies. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Correlation of pectoral NCS with electromyography and magnetic resonance imaging. RESULTS: For pectoral NCS, the mean values +/- standard deviation of onset latency, amplitude, and interside amplitude ratio (ratio of smaller over larger amplitude) were 2.01+/-0.22 ms, 11.75+/-2.21 mV, and .95+/-.04 mV, respectively. Subject age correlated significantly with both onset latency (r=.46, P<.001) and amplitude (r=-.34, P<.008). All 5 patients with brachial plexopathy had amplitude ratios below the normal limit of controls (.87). However, this was not seen for all 5 patients with cervical spondylotic radiculopathy. CONCLUSIONS: The pectoral NCS technique is feasible in healthy subjects. It is useful when differentiating brachial plexopathy from cervical root lesions.

Adult↗
PubMed2005

The silent period threshold as a measure of corticospinal inhibition.

Corticomotor threshold is a clinically useful concept for defining motor cortex excitability using transcranial magnetic stimulation. Although the silent period duration can be a quantitative measure of corticospinal inhibitory function, its threshold value has not been formally determined. The authors studied 20 right-handed normal subjects and found that silent period threshold was a reproducible parameter that did not vary with age and sex. Its value was significantly lower with left-sided transcranial magnetic stimulation and right-hand recordings. The silent period threshold may be a novel parameter useful for future studies of cortical inhibitory function.

Adult↗
PubMed2003

Vocal fold paralysis following radiotherapy for nasopharyngeal carcinoma: laryngeal electromyography findings.

Laryngeal electromyography was used to study the pattern of neurological injury in three patients with unilateral vocal fold paralysis following radiotherapy for nasopharyngeal carcinoma. The thyroarytenoid and cricothyroid muscles were assessed to give an indication of recurrent and superior laryngeal nerve function. Two patients demonstrated both recurrent and superior laryngeal neuropathy suggesting injury at the skull base. The other patient had only recurrent laryngeal neuropathy indicating more distal involvement. Subclinical neuropathic changes were seen in two cases on the side contralateral to the vocal fold paralysis. These patients may be at increased risk of developing bilateral vocal fold paralysis and potentially life-threatening airway obstruction. Long-term follow-up is recommended for such patients, especially if medialization thyroplasty is being considered. This is the first report describing the use of electromyography to determine the pattern of nerve injury in patients with vocal fold paralysis following head and neck radiotherapy.

Carcinoma↗
PubMed2002

Mixed nerve potentials in brachial plexopathy.

We studied the Erb's point potential with supramaximal stimulation of the median nerve in 14 consecutive patients with clinical and electrophysiological evidence of unilateral brachial plexopathy and in normal controls. Both arms were studied in each individual. In each patient, the ratio of amplitude of recorded Erb's point potential from the affected arm to the normal arm was calculated. In controls the side with a recorded potential of a lower amplitude was used as the numerator to calculate a similar ratio. Eleven out of 14 patients had a Erb's point amplitude ratio less than that of controls. This method is a simple and useful adjunct in the electrophysiological assessment of brachial plexopathy.

Adult↗
PubMedDate not supplied

Effect of exercise on repetitive nerve stimulation studies: new appraisal of an old technique.

Repetitive nerve stimulation (RNS) is a simple and rapid method for evaluation of neuromuscular transmission defects. Although the effect of exercise in conjunction with RNS is well recognized, it has not been standardized in actual patient and control groups. In a prospective study over a period of 1 year, the authors evaluated the effect of exercise in conjunction with RNS in comparison with conventional 3-Hz RNS at rest in the clinical setting. Fifty-four patients who were referred for possible neuromuscular transmission disorders, in addition to 35 healthy control subjects, were studied. Amplitude and area decremental responses with RNS at rest and after 20 seconds of maximal exercise at 1-minute intervals up to 3 minutes were evaluated. The use of RNS with exercise resulted in additional diagnostic yield of up to 36.4% compared with conventional 3-Hz RNS at rest. The standardized use of exercise with RNS is advocated for increasing its diagnostic yield in the neurophysiologic laboratory.

Adult↗