Is thyrotoxic periodic paralysis a disease caused by muscle membrane dysfunction?

INTRODUCTION: Thyrotoxic periodic paralysis (TPP) is characterized by recurrent episodes of reversible paralysis with hyperthyroidism. It is clinically similar to hypokalemic periodic paralysis (HOPP), which features significant ion-channel dysfunction and reduced muscle fiber conduction velocity (MFCV). However, the muscle membrane function in TPP is not known. METHODS: For 13 patients with TPP and 15 age-matched controls, clinical assessment and serial neurophysiological testing, including nerve conduction, prolonged exercise (PE) testing, and MFCV. were performed. RESULTS: MFCV values were elevated up to 1 year from the paralytic attack in TPP patients. In the group with a positive PE test, MFCV values were higher. There was no significant relationship between MFCV values and either hypokalemia or hyperthyroidism. CONCLUSIONS: Although clinical manifestations in TPP are similar to those observed in HOPP, TPP appears to feature an alternate pathogenic mechanism. Specifically, MFCV values increased rather than decreased. Further studies are needed to support these findings. Muscle Nerve, 2016 Muscle Nerve 56: 780-786, 2017.

A Simple Geometric Assessment of Perfusion Lesion Volume at Hyperacute Stage of Ischemic Stroke in Patients with Symptomatic Steno-Occlusion of Major Cerebral Arteries and Risk of Subsequent Cerebral Ischemic Events.

Our objective is to elucidate the association of baseline perfusion lesion volume on perfusion-weighted magnetic resonance imaging (PWI) obtained at hyperacute stage of ischemic stroke with subsequent cerebral ischemic events (SIEs) in patients with symptomatic steno-occlusion of major cerebral arteries. Using a prospective stroke registry database, patients arriving within 24 hours of onset with symptomatic steno-occlusion of major supratentorial cerebral arteries were identified. On baseline PWI, time-to-peak lesion volume (TTP-LV) was determined by a simple geometric method and dichotomized into the highest tertile (large) and the other tertiles (small to medium) according to the vascular territory of occluded arteries. Primary outcome was a time to SIE up to 1 year after stroke onset. A total of 385 patients (a median time delay from onset to arrival, 2.2 hours) were enrolled. During the first year of stroke, the SIE rate of the large TTP-LV group was twice that of the small-to-medium TTP-LV group (35.7% versus 17.4%; P < .001). Large TTP-LV independently raised the hazard of SIE (hazard ratio, 2.24; 95% confidence interval, 1.45-3.44). This study demonstrates that TTP-LV on PWI measured through a simple geometric method at an emergency setting can be used to predict progression or recurrence of ischemic stroke in patients with symptomatic steno-occlusion of major cerebral arteries.

Differences in Multimodality Intraoperative Neurophysiological Monitoring Changes Between Spinal Intramedullary Ependymoma and Hemangioblastoma.

INTRODUCTION: Intraoperative neurophysiological monitoring using transcranial muscle motor evoked potentials (MEPs) and somatosensory evoked potentials is an established method for intramedullary spinal cord tumor surgery. Ependymomas and hemangioblastomas arise in different anatomic locations and require different surgical techniques. The aim of our study was to assess differences in intraoperative neurophysiological monitoring findings between ependymoma and hemangioblastoma. METHODS: Fifty-six limbs from 16 patients diagnosed with ependymoma and 18 limbs from six patients with hemangioblastoma were included. The alarm criterion for MEPs was a 50% decrease in amplitude, whereas for somatosensory evoked potentials, it was a 50% decrease in amplitude and/or a 10% delay in latency. RESULTS: We found that 14 of the 56 ependymoma limbs (25.9%) and 8 of the 18 hemangioblastoma limbs (44.4%) showed MEP decrement during surgery. Eight limbs of patients with ependymoma (57.1%) and one limb of a patient with hemangioblastoma (12.5%) did not show recovery of MEPs at the end of surgery. Among those who showed recovery of MEPs, six ependymoma (10.7%) and six hemangioblastoma (33.3%) limbs did not show postoperative motor deficits (P = 0.04). Finally, 11 limbs of patients with ependymoma and one limb of a patient with hemangioblastoma showed postoperative weakness. CONCLUSIONS: In our study, the incidence of transient changes in MEPs was higher in hemangioblastoma than in ependymoma. Our data suggest that it may be necessary to consider tumor features and the type of surgical technique used, particularly when interpreting intraoperative neurophysiologic monitoring profiles of intramedullary spinal cord tumors such as ependymomas and hemangioblastomas.

Balo's Concentric Sclerosis Mimicking Cerebral Tuberculoma.

Balo's concentric sclerosis (BCS) is considered a rare variant of multiple sclerosis, which often mimics an intracranial neoplasm or abscess. We report the case of a 21-year-old woman presenting with BCS while undergoing treatment for pulmonary tuberculosis. Initial brain magnetic resonance imaging (MRI) findings were similar to those for cerebral tuberculoma, multiple metastases, or abscesses. However, the pathognomonic concentric sclerosis characteristic of BCS was seen on MRI. The antemortem confirmatory diagnosis of BCS was made by follow-up MRI and a brain biopsy. It is suggested that BCS should be included in the differential diagnosis of cerebral tuberculoma, especially in developing countries with a high prevalence of tuberculosis.