Many referrals to neurological services are for episodes of transient loss of consciousness (TLoC), more often as a consequence of syncope than epileptic seizure. The neurological component of these events is reflected in terms such as “neurally-mediated syncope”, “neurocardiogenic syncope”, and “reflex syncope”, but because the efferent limb of this reflex produces circulatory effects (cardio-inhibitory: bradycardia; and vasodepressor: hypotension) it often also falls to cardiologists to assess these patients. Few neurologists have an expressed interest in these conditions (this book clearly shows that syncope is no more a unitary condition than epileptic seizure). This may be because the division of the nervous system at fault is the autonomic branch, which, perhaps akin to stroke, has traditionally failed to draw many neurological recruits. Accordingly, although it clearly behoves neurologists to have some familiarity with syncope, it has largely been cardiologists who have driven the agenda in terms of research and guidelines. Since TLoC crosses professional clinical boundaries, one can see the point of dedicated “Syncope units”.
This book, itself from a “Cardiology” series, contains chapters on syncope epidemiology, pathophysiology, clinical and diagnostic aspects, prognosis and treatment, as well as related topics, including the relationship to fibromyalgia, chronic fatigue syndrome, and postural orthostatic tachycardia syndrome (POTS), all of which may also feature in neurological practice (and may be associated with autonomic dysfunction).
Although typical syncope may be easily diagnosed on clinical grounds alone, atypical syncope presents significant challenges, sometimes requiring tilt-testing, an investigation absent from the menu at most neurological centres. There is no syncope biomarker, although B-type natriuretic peptides are being examined (there is no mention of co-peptin, despite a 2013 paper suggesting its potential utility). Implantable loop recorders have illuminated pathophysiology and provided indications for pacemaker insertion in some patients, but these obviously fall outwith the neurological remit.
Considering the differential diagnosis, I was initially surprised to see the inclusion of cataplexy (p31,174,282), but as many episodes of syncope in the elderly may present as “unexplained falls” with minimal or no prodromal symptoms and/or retrograde amnesia, this differential is logical. Cognitive testing is advocated in elderly patients with unexplained falls (p290). Syncope is often contrasted with epileptic seizure, but surprisingly there is no mention of NEAD as another differential, although this may overlap with “functional (psychogenic) pseudosyncope”. The roles of non-pharmacological (e.g. counter pressure manoeuvres) and pharmacological treatments for syncope have little existing evidence base, of the latter the best evidence is probably for midodrine.
In my judgment, this book may be recommended to neurologists seeking a refresher or wanting to learn more about this topic. The contributors are mostly Italian (such is the enthusiasm that even Calgary is claimed to be in Italy! See p297), leading to some infelicities of language (persistent use of “associated to” irked me; “conclusive” for “concluding”). The absence of an index is a serious deficiency!
ACNR 2015;15(5):17. Online 13/11/2015
