Commentary.

Atypical presentations of well-known diseases have the uttermost importance when they delay the implementation of effective therapies. Herpes encephalitis, as presented by Vachalová and colleagues in this issue of JNRP, serves as an example of such problem.[1] Both the limitations of diagnostic tests and the importance of clinical suspicion in herpetic encephalitis have been underlined in the literature.[2] During the past three decades, antiviral drugs have brought a therapeutic improvement that clearly changed outcome in these patients. In that setting, early diagnosis is critical.[3] Attempts have been made to establish diagnostic guidelines that facilitate management, thus minimizing the ever-present number of patients that does not benefit from early treatment due to atypical manifestations.[456] With their description of cases with confusing initial symptoms, Vachalová and colleagues illustrate this situation, as well as the importance of careful semiology, differential diagnosis, clinical suspicion, and purposeful combination of different tests. Clinical practice has to acknowledge a certain degree of uncertainty. To control this factor, the clinician has to possess a precise, structured, operative knowledge of syndromes, while at the same time, he keeps “in the back of his mind” the possibility of facing an atypical condition.[7] Even more, while it is a basic ability for any clinician to recognize the definite manifestations of a given disease, he has to be prepared for the myriad of situations surrounding a particular patient that will mislead diagnosis and therapeutics. Sometimes, we encounter more than one simultaneous diagnosis in a patient. Or co-morbidities, the relevance of which has to be pondered, whether they are simple or complex. Or we may have to translate the patient's symptoms, being its expressivity conditioned by his personal or social background. The skill to blend what is relevant of these situations with the information gathered through anamnesis and examination has to be taught during medical training, but it is also the fruit of experience and, sometimes, the fruit of intuition.[8] In every specialty, common cases are the most frequent, but sporadic patients dramatically remind us about the challenges of clinical practice.