Shih-Tseng Lee

Electrical stimulation of the anterior nucleus of the thalamus for intractable epilepsy: a long-term follow-up study.

Summary:  Purpose: The anterior nucleus of the thalamus (ANT) modulates temporal lobe and hypothalamic activities, and relays information to the cingulate gyrus and entorhinal cortex. Deep brain stimulation (DBS) of the ANT has been reported to decrease seizure activity in a limited number of human subjects. However, long‐term effect of chronic ANT stimulation on such patients remains unknown. We report long‐term follow‐up results in four patients receiving ANT stimulation for intractable epilepsy.

Early seizures after moderate closed head injury

SummaryThe incidence and clinical significance was studied in 2574 closed head injury patients, each of them having a Glasgow Coma Scale (GCS) 9 to 12 after trauma. All patients underwent computerized tomography (CT) after being admitted to the emergency service. One hundred and six patients (4.1%) experienced seizures within 1 week after head injury; 46 of these (1.8% of the series) had seizures within 24 hours after trauma. There was no statistically significant difference between the early seizure and seizure free group of patients in gender, age and GCS with the exception of cause of injury (p < 0.01). The incidence of intracerebral parenchymal damage was found to be higher with seizures developing between day 2 and day 7 (80%) than those with seizures developing within 24 hours (54.3%). Analysing the data revealed that early posttraumatic seizures were not related to the presence of intracerebral parenchymal damage on CT scan. The occurrence of early seizures did not affect the mortality and outcome of moderate closed head injury patients.

Relative risk of deterioration after mild closed head injury

SummaryIn this prospective study, a series of 1812 consecutive mild head injured adult patients who visited the hospital emergency department were assessed. Twenty-eight patients (1.5%) deteriorated after head injury; 23 of these (1.3% of the series) required surgical intervention. Five patients (0.3%) deteriorated due to non-surgical causes [post-traumatic seizure 2, syndrome of inapproapriate secretion of antidiuretic hormone (SIADH) 3]. Most of the deterioration occurred within the first 24 hours (57%). Post-traumatic headache was found in 280 patients (15.5%) and 84 patients (4.6%) suffered post-traumatic vomiting.The relative risk is calculated. Age over 60, presence of drowsiness, focal motor weakness, post-traumatic headache and vomiting has increased risk of deterioration (p < 0.001). This study suggests that post-traumatic headache and vomiting deserve more clinical attention rather than being considered as post-traumatic syndrome only.

Detection of neuronal spikes using an adaptive threshold based on the max–min spread sorting method

Neuronal spike information can be used to correlate neuronal activity to various stimuli, to find target neural areas for deep brain stimulation, and to decode intended motor command for brain-machine interface. Typically, spike detection is performed based on the adaptive thresholds determined by running root-mean-square (RMS) value of the signal. Yet conventional detection methods are susceptible to threshold fluctuations caused by neuronal spike intensity. In the present study we propose a novel adaptive threshold based on the max-min spread sorting method. On the basis of microelectrode recording signals and simulated signals with Gaussian noises and colored noises, the novel method had the smallest threshold variations, and similar or better spike detection performance than either the RMS-based method or other improved methods. Moreover, the detection method described in this paper uses the reduced features of raw signal to determine the threshold, thereby giving a simple data manipulation that is beneficial for reducing the computational load when dealing with very large amounts of data (as multi-electrode recordings).

Spinal cord herniation after stabbing injury

A 19-year-old man presented with delayed paraplegia on the second day after a stab injury of the spine. Magnetic resonance imaging showed herniation of the spinal cord through the dural defect. After emergency surgery, his paraplegia recovered leaving a Brown-Sequard syndrome immediate after injury. Spinal cord herniation should be considered as one of the possible factors in patients developing neurological deterioration after a stab injury of the spine. The possible pathogenesis of symptomatic non-spontaneous spinal cord herniation is discussed.

Intracerebral osteoma: Case report

A 28-year-old woman presented with 6 months of intractable left frontal headache that was proved to be due to an intracranial lesion. After successful surgical removal, it was found to be an intracerebral osteoma without a dural attachment. The literature of intracerebral osteoma is reviewed.

Classification of neuronal spikes over the reconstructed phase space.

Spike information is beneficial to correlate neuronal activity to various stimuli or determine target neural area for deep brain stimulation. Data clustering based on neuronal spike features provides a way to separate spikes generated from different neurons. Nevertheless, some spikes are aligned incorrectly due to spike deformation or noise interference, thereby reducing the accuracy of spike classification. In the present study, we proposed unsupervised spike classification over the reconstructed phase spaces of neuronal spikes in which the derived phase space portraits are less affected by alignment deviations. Principal component analysis was used to extract major principal components of the portrait features and k-means clustering was used to distribute neuronal spikes into various clusters. Finally, similar clusters were iteratively merged based upon inter-cluster portrait differences.

Unsupervised wavelet-based spike sorting with dynamic codebook searching and replenishment

Spike information is beneficial for correlating neuronal activity to various stimuli, finding target neural areas for deep brain stimulation, and decoding intended motor command for brain-machine interface. Unsupervised classification based on spike features provides a way to separate spikes generated from different neurons. Here, we propose an unsupervised spike sorting method based on specific wavelet coefficients (SWC) and using both a new spike alignment technique based on multi-peak energy comparison (MPEC) and a dynamic codebook-based template-matching algorithm with a class-merging feature. The MPEC alignment reduced inconsistent alignment caused by spike deformation. Using SWC not only reduced the number of features but also performed better in terms of matching a neuronal spike to its own class than relying on spike waveform or whole wavelet coefficients. Moreover, the employed codebook searching and replenishment can be operated in an online, real-time mode.

Delayed spontaneous tension pneumocephalus caused by radionecrosis of the skull base

We report a case of spontaneous tension pneumocephalus which occurred 6 years after radiotherapy for a nasopharyngeal carcinoma. A skull base defect and nasocranial fistula causing tension pneumocephalus was identified, and was repaired successfully. It proved to be due to skull base osteoradionecrosis.

Low and High Frequency Hippocampal Stimulation for Drug-Resistant Mesial Temporal Lobe Epilepsy.

Electrical stimulation of the hippocampus offers the possibility to treat patients with mesial temporal lobe epilepsy (MTLE) who are not surgical candidates. We report long‐term follow‐up results in five patients receiving low or high frequency hippocampal stimulation for drug‐resistant MTLE.