Timing of Decremental Response During Repetitive Nerve Stimulation in Myasthenia Gravis

Background: A decrement >10% detected during repetitive nerve stimulation (RNS) is supportive of considering a diagnosis of myasthenia gravis (MG). Several studies have found that most of this decrement is seen between 4 to 6 min post-exercise. However, there are not available studies analyzing if shorter timing would be sufficient.   Objective: The objective of this study was to evaluate if RNS up to 2 min post-exercise is sufficient to detect a decrement response >10%. Methods: We performed a retrospective chart review study of patients referred to our neuromuscular clinic at The University of Kansas Medical Center with symptoms suggestive of MG from 2013 to 2017. Results: A total of 76 patients with MG and 100 controls were identified.  A significant decrement was detected in 95% of MG patients with abnormal RNS within 2 minutes post-exercise. Conclusion: RNS up to 2 min post-exercise might be sufficient to detect a significant decrement in MG patients.&nbsp

Eyelid myotonia and face stiffness in skeletal muscle sodium channelopathy

Title Eyelid myotonia and face stiffness in skeletal muscle sodium channelopathy Video Legend Video 1. Notice the delayed relaxation of the eyelids after forced eye closure (eyelid myotonia). Also, notice the full facial hair to prevent facial muscle stiffening exacerbation with cold weather. AuthorsSrijan Adhikari, MBBS, Jeffrey Statland, MD, Constantine Farmakidis, MD Authors information: Srijan Adhikari, MBBS, ORCID ID: 0000-0001-9653-3079, University of Kansas Medical Center, Department of Neurology, Kansas City, Kansas, USAJeffrey Statland, MD, ORCID ID: 0000-0003-0790-5315 University of Kansas Medical Center, Department of Neurology, Kansas City, Kansas, USAConstantine Farmakidis, MD, ORCID ID: 0000-0002-4688-9224, University of Kansas Medical Center, Department of Neurology, Kansas City, Kansas, USA Corresponding Author Srijan Adhikari, MBBS,Department of Neurology,University of Kansas Medical Center,3901 Rainbow Boulevard., MS 2012,Kansas City, KS [email protected] Author Conflict of Interests Dr Adhikari has nothing to disclose.Dr. Statland reports grants from NIH, grants from MDA, grants from FSHD Society, grants from Friends of FSH Research, personal fees from Dyne, personal fees from Fulcrum, personal fees from Avidity, personal fees from MT Pharma, personal fees from Acceleron, personal fees from Sarepta, personal fees from Strongbridge, outside the submitted work. Dr. Farmakidis reports personal fees from Argnex, personal fees from Momenta, personal fees from Terumo BCT, outside the submitted work

Cough syncope

SummaryLoss of consciousness following cough was first described in 1876 as “laryngeal vertigo” Since then, several hundred cases of what is now most commonly termed cough syncope have been reported, often in association with various medical conditions. Some early authors assumed this entity to be a form of epilepsy, but by the mid-20th century, general consensus reflected that post-tussive syncope was a consequence of markedly elevated intrathoracic pressures induced by coughing. A typical profile of the cough syncope patient emerging from the literature is that of a middle-aged, large-framed or overweight male with obstructive airways disease. Presumably, such an individual would be more likely to generate the extremely high intrathoracic pressures associated with cough-induced fainting. The precise mechanism of cough syncope remains a matter of debate. Theories proposed include various consequences of the marked elevation of intrathoracic pressures induced by coughing: diminished cardiac output causing decreased systemic blood pressure and, consequently, cerebral hypoperfusion; increased cerebrospinal fluid (CSF) pressure causing increased extravascular pressure around cranial vessels, resulting in diminished brain perfusion; or, a cerebral concussion-like effect from a rapid rise in CSF pressure. More recent mechanistic studies suggest a neurally mediated reflex vasodepressor-bradycardia response to cough. Since loss of consciousness is a direct and immediate result of cough, elimination of cough will eliminate the resultant syncopal episodes. Thus, the approach to the patient with cough syncope requires thorough evaluation and treatment of potential underlying causes of cough, as summarized in several recently published cough management guidelines