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Show Editorial How Neurologists and Neuro-Ophthalmologists Think Michael Benatar, MD, PhD C linical decision making, which lies at the heart of diagnostic reasoning and therapeutic selection, is a complex affair. Most of us intuitively simplify this process by using heuristics (cognitive shortcuts) that typically yield the right diagnosis and enable us to make appropriate therapeutic recommendations. The heuristic method, however, is inherently prone to error precisely because it entails simplification of a complex process. It is helpful, therefore, to occasionally step back, deconstruct the way in which we think, and reflect on the ways in which our clinical reasoning might go awry (1). In addition, growing subspecialization within medicine increases the likelihood that physicians approach clinical problems exclusively from their own perspective. This, in turn, carries with it the risk that we may neglect essential information and be biased toward particular diagnoses and therapeutic approaches. Several articles in this issue of the Journal of Neuro-Ophthalmology provide an opportunity to discuss such matters. In a Point Counter-Point discussion, Wong et al (2) debate the question of whether early treatment of patients with ocular myasthenia gravis with immunosuppressive therapy prevents secondary generalization and, as such, whether such treatment should be offered to all patients. In arguing for their respective positions, the authors focus primarily of what is known (and what is not) about the benefits of corticosteroids and other immunosuppressive agents in reducing the risk of progression from ocular to generalized myasthenia gravis, and also the potential harmful effects with the use of these therapeutic agents. Worth noting, however, is that the limited scope of the question has the potential to constrain the answer. The decision whether to recommend corticosteroids and other immunosuppressive agents is impacted not only by their potential effect on reducing the risk of progression to generalized disease but also by their potential to improve the ocular symptoms of ptosis and diplopia. Data from the recently published EPITOME trial help clarify the issue, providing new evidence that low-dose corticosteroids may be safe and effective in treating the symptoms of ocular myasthenia (3). Although these data do not definitively address the question of the pros and cons of corticosteroid therapy for patients with ocular myasthenia, they do underscore the point that "framing" or constraining the discussion of this important therapeutic question by considering only the impact of corticosteroids and other immunosuppressive agents on the risk of progression to generalized disease risks ignoring other highly relevant information. Framing effects may also constrain our diagnostic reasoning process although a discussion of this is beyond the scope of this editorial. The foregoing Point Counter-Point discussion along with the article by Young and Leavitt (4) about ocular signs and symptoms in the Lambert-Eaton myasthenic syndrome (LEMS) also highlights one of the challenges we all face in an era of highly subspecialized medicine, which is that we run the risk of approaching problems exclusively from our own limited professional perspective. In a retrospective review of 176 patients with LEMS seen at the Mayo Clinic, ptosis was found in 45 patients (26%) and abnormal ocular motility in 15 (8.5%). But only 42 patients (24%) had been evaluated by an ophthalmologist. In the same way, neurologists might have missed ocular signs that a neuroophthalmologist would detect; neuro-ophthalmologists probably are not quite as adept at carefully evaluating the strength of nonocular muscles as neuromuscular specialists. As such, signs of generalized weakness might be missed by (neuro)-ophthalmologists who manage patients with myasthenia without input from a neurologist. Failure to recognize subtle weakness of triceps, neck flexors, or other nonocular muscles might lead to the mistaken conclusion that a patient has ocular disease when, in fact, Professor of Neurology and Public Health Sciences, Department of Neurology, Miller School of Medicine, Miami, Florida. Address correspondence to Michael Benatar, MD, PhD, Professor of Neurology and Public Health Sciences, Department of Neurology, Miller School of Medicine, Miami, FL; E-mail: mbenatar@med.miami.edu 4 Benatar: J Neuro-Ophthalmol 2016; 36: 4-5 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Editorial they have generalized myasthenia. For both neurologists and neuro-ophthalmologists, therefore, there is a need to strive to avoid the perspective captured by the epithet "to a man with a hammer, everything appears as a nail" (5). Likewise, we cannot quantify the frequency of steroid side effects (and hence accurately appraise costs in a cost-benefit analysis) if we do not proactively seek out and identify such side effects in the patients we treat with corticosteroids. Clearly, we cannot make the right therapeutic decisions if we lack essential clinical data, a point well made by a number of the authors of the articles in this issue of the Journal. Finally, the article by Chapman et al (6) describes the rare occurrence of thymic amyloidosis in a patient with ocular myasthenia and raises the challenge of correctly diagnosing rarities when they do arise, but without overdiagnosis of such "canaries" on other occasions. As physicians, we are prone to the latter because we often ignore population frequencies of disease (i.e., previous probabilities) when we use the pattern recognition heuristic as a diagnostic aid (1). We are all familiar with the clinical maxim "if you hear hoof beats, think about horses, not zebras," which exalts us to remember that uncommon manifestations of a common disease occur more frequently than common manifestations of uncommon diseases. And yet neuromuscular specialists and neuro-ophthalmologists alike face the daily challenge Benatar: J Neuro-Ophthalmol 2016; 36: 4-5 that so many of the diseases that afflict our patients are each individually rare. By periodically raising our collective awareness of blind spots and biases in the way we collect clinical data, and also the heuristics we use to aid the diagnostic process, as these three articles do, we are more likely to be conscious of the constraints these cognitive approaches impose and thereby improve our clinical reasoning and the quality of the care we provide to our patients. REFERENCES 1. Vickrey BG, Samuels MA, Ropper AH. How neurologists think: a cognitive psychology perspective on missed diagnoses. Ann Neurol. 2010;67:425-433. 2. Wong SH, Plant G, Cornblath W. Does treatment of ocular myasthenia gravis with early immunosuppressive therapy prevent generalization and should it be offered to all such patients? J Neuroophthalmol. 2016;36:93-97. 3. Benatar M, McDermott MP, Sanders DB, Wolfe GI, Barohn RJ, Nowak RJ, Hehir M, Juel V, Katzberg H, Tawil R. Efficacy of prednisone for the treatment of ocular myasthenia (EPITOME): a randomized controlled trial. Muscle Nerve. [published online ahead of print July 14, 2015] doi: 10.1002/mus.24769. 4. Young JD, Leavitt JA. Lambert-Eaton myasthenic syndrome: ocular signs and symptoms. J Neuroophthalmol. 2016;36:20-22. 5. Robertson I. To a man with a hammer, everything looks like a nail. BMJ. 1993;306:937. 6. Chapman K, Beneck DM, Dinkin MJ. Ocular myasthenia gravis associated with thymic amyloidosis. J Neuroophthalmol. 2016;36:50-52. 5 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. |
