Once more unto the breach, dear friends, once more;
Or close the wall up with our English dead.
In peace there's nothing so becomes a man
As modest stillness and humility:
But when the blast of war blows in our ears,
Then imitate the action of the tiger;
Stiffen the sinews, summon up the blood,
Disguise fair nature with hard-favour'd rage;
Then lend the eye a terrible aspect;
Let pry through the portage of the head
Like the brass cannon; let the brow o'erwhelm it
As fearfully as doth a galled rock
O'erhang and jutty his confounded base,
Swill'd with the wild and wasteful ocean.
Now set the teeth and stretch the nostril wide,
Hold hard the breath and bend up every spirit
To his full height. On, on, you noblest English.
-William Shakespeare, Henry V
As a first-year medical student, I listened raptly as my professor indicated how the Bard, with these brilliant words, demonstrated his knowledge and understanding of the flight or fight response mediated by the autonomic nervous system (ANS). Unfortunately, for many of us neurologists, understanding of this complicated system and its potential dysfunction is quite imperfect. In this issue of CONTINUUM, Dr Horacio Kaufmann has assembled an outstanding faculty to help us grasp the intricacies of the ANS, learn better how to assess it, and become more familiar with the conditions that affect it.
The issue begins with a review of the anatomy and physiology by Dr Eduardo Benarroch, followed by a practical discussion of the clinical evaluation of the ANS by Drs David Goldstein and Phillip Low. Subsequent chapters address more specific disorders. Syncope is undoubtedly one of the most frequent conditions for which neurologists are consulted. Dr Roy Freeman and Dr Kaufmann next discuss this common disorder, focusing particularly on the variety of syndromes associated with orthostatic intolerance. They include an explication of the condition of postural tachycardia, with which neurologists may be less familiar than they are with some other orthostatic syndromes. Dr Steven Vernino next teams up with Dr Freeman to review a variety of peripheral autonomic neuropathies, many of which are immunologically mediated. Neurodegenerative disorders, particularly several with a parkinsonian phenotype, have prominent autonomic dysfunction; Drs Kaufmann and Goldstein partner to review this subject.
Turning to ailments that neurologists may consider less often, Dr William Cheshire and Dr Low discuss disorders of sweating and thermoregulation, ranging from severe and life-threatening hypothermia and hyperthermia to the embarrassing disorder of palmar hyperhidrosis.
On the other hand, urinary dysfunction affects many patients that neurologists commonly encounter, particularly those with multiple sclerosis. Dr Clare Fowler reviews this subject and also discusses the syndrome of urinary retention in young women, a condition perhaps less well-known to neurologists. No one is better suited to discuss this subject than Dr Fowler, whose name has been attached to the syndrome. Although neurologists may often view gastrointestinal (GI) tract disturbances as the province of gastroenterologists, frequently the symptoms, involving either the upper or lower GI tract, have their genesis in autonomic dysfunction and, hence, deserve consideration and management by neurologists. Drs Chris Abrasley and Thomas Abell address this subject. Finally, Dr Clifford Saper educates us about visceral sensation and visceral sensory disorders, including such entities as disturbance of taste, glossopharyngeal neuralgia, the syndrome of inappropriate antidiuretic hormone secretion, and visceral pain syndromes. He also introduces the subject of the role of the ANS in addiction and cravings, emphasizing the importance of the insular cortex.
As usual, the formal didactic chapters are complemented by discussion of an ethical issue and, now, a practice-related matter. In the former, Dr Cheshire addresses the matter of a patient demanding genetic testing and the implications of such investigations. Dr Michael Kaminski discusses important issues of patient safety in the practice section. Readers may not only test the knowledge they have gained by reading this issue of CONTINUUM, but acquire still more information, by answering the multiple-choice questions crafted by Dr Benarroch and Dr Joanne Lynn, as well as by working through the patient management exercise developed by Dr Italo Biaggioni and Dr Kaufmann.
Confronted by a patient with disturbances of autonomic function, neurologists may find themselves victims of the autonomic ramifications of fear and anxiety. After reading this issue so cogently crafted by Dr Kaufmann and his collaborators, your own "fight or flight" response will undoubtedly veer toward the former, as you are prepared to do battle with these difficult and often enigmatic patients.
-Aaron E. Miller, MD