Ep157 Neuromuscular Disease for Emergency Medicine

There is a long list of rare neuromuscular diseases. Nonetheless, there are a few that you are likely to see in the ED, that are relevant to Emergency Medicine because they require timely diagnosis and treatment. In this Part 2 of our 2-part series on acute motor weakness with Roy Baskind and George Porfiris, we keep it short and simple by limiting our discussion to the key clinical clues and management strategies of two of the more common acute life-threatening neuromuscular diseases, myasthenia gravis and Guillain Barré syndrome, and how to distinguish them from their mimics... Podcast production, sound design & editing by Anton Helman; voice editing by Raymond Cho. Written Summary and blog post by Saswata Deb & Priyank Bhatnagar, edited by Anton Helman June, 2021 Cite this podcast as: Helman, A. Baskin, R. Porfiris, G. Neuromuscular Disease for Emergency Medicine. Emergency Medicine Cases. June, 2021. https://emergencymedicinecases.com/neuromuscular-disease. Accessed [date] Go to part 1 of this 2-part podcast on acute motor weakness Guillain-Barré syndrome and myasthenia gravis are two neuromuscular disorders that can present with rapid respiratory compromise and subsequent mortality. Fortunately, they both present with hallmarks of clinical diagnosis that the emergency physician can use for early recognition. Guillain-Barre syndrome (GBS): The areflexic ascending symmetric neuromuscular disease Guillain-Barre syndrome is an autoimmune disorder of the myelin sheath characterized by an acute/subacute onset of progressive peripheral polyneuropathy, symmetrical distribution, ascending pattern of loss of power and areflexia. GBS has a 5% mortality risk, with one-third of patients requiring endotracheal intubation and ICU admission. Even non-ventilated patient can have prolonged admissions of up to 5 weeks. Recovery is also slow, with 50-95% of patients taking a year to return to baseline functional status. Areflexia and ascending symmetrical weakness are the hallmarks of GBS The loss of deep tendon reflexes in the patient with acute loss of symmetric ascending motor power should be considered GBS until proven otherwise. It is incumbent upon the EM provider to assess for deep tendon reflexes carefully, employing passive control of the patient's limb and distraction techniques (such as asking the patient to count backwards from 100 in serial 7s) while eliciting reflexes. With a delay in diagnosis autonomic dysfunction ensues, resulting in swings of tachy/bradycardia and hypo/hypertension as well as diaphragmatic and respiratory muscle weakness and respiratory failure. Despite complaints of numbness and tingling, sensation testing is usually intact in GBS. The presence of a sharp sensory level points to alternative diagnoses such as transverse myelitis. Preceding viral infections are common in GBS but not necessary for the diagnosis. Up to two-thirds of patient with GBS report preceding viral symptoms. One of the more common viral infections seen in this context is Campylobacter jejuni gastroenteritis. Early diagnosis and initiation of treatment of GBS is essential to prevent autonomic dysfunction and respiratory compromise Early treatment of GBS is thought to prevent the progression to autonomic dysfunction and respiratory arrest as well as the need for ICU care/endotracheal intubation. The most effective treatment of GBS is plasma exchange, however it is not readily available at many centers. Hence, IVIG therapy is usually the first line treatment, and if it fails, then plasma exchange is usually initiated. The two important alternate diagnoses to consider in GBS are tick paralysis and transverse myelitis