Correspondence Rate of progression differs in frontotemporal dementia and Alzheimer disease To the Editor: Rascovsky et al. collected data from several Alz- heimer’s Disease Research Centers (ADRCs) on 70 autopsy diag- nosed frontotemporal dementia (FTD) and matching Alzheimer disease (AD) cases. 1 Their claim of the more “malignant” course of FTD echoes recent articles yet is contradicted by their own data such as the same course and duration of illness from onset to death in both groups. We found the same in a recent autopsy series 2 and so did others as cited in the article. Rascovsky et al.’s emphasis on the shorter duration from initial assessment to death may be mis- placed, as they state, “.. FTD patients were actually farther along in disease course than those with AD at the time of initial evalu- ation given the observed differences in functional impairment at baseline.” They also discuss why the Mini-Mental State Examination (MMSE) may not be sensitive to the earliest changes and why the drop observed at a 1-year follow-up could be related to the lan- guage deterioration commonly seen in FTD in middle stages. Mo- tor neuron disease may shorten the duration of FTD substantially, but this did not seem to be the case here as it might have been in other series. The more severe activities of daily living (ADL) impairment at initial assessment reflects the clinical reality and the fundamental difference between the two conditions. Patients with FTD neglect their hygiene and dress and often have an eating disorder yet their memory and spatial function may remain intact. In contrast, patients with AD are often well dressed, socially appropriate, and yet incapacitated by memory and spatial loss at presentation. Which one is more malignant often depends on the caregiver’s point of view. Andrew Kertesz, MD, FRCP(C), FAAN, London, Ontario, Canada Disclosure: The author reports no conflicts of interest. Reply from the Authors: We thank Dr. Kertesz for his interest in our article. 1 We agree with his point that behavioral symptoms may precede significant cognitive decline in FTD, making it diffi- cult to precisely define disease onset. Time of disease onset is also difficult to accurately estimate in AD, so it is not surprising that comparisons of disease duration based upon these estimates have produced mixed results. This is exactly what led us to use both the relatively “soft” starting point of estimated onset and the known benchmark of initial clinic presentation in comparing survival in FTD and AD. Kertesz et al.’s excellent article 2 describing the chronology of clinical features and neuropathology in FTD sheds little addi- tional light as it reports survival based only on estimated disease onset and compares patients with FTD with a small group of atypical patients with AD. It is worth noting, however, that our finding regarding survival has been replicated in a larger series, 3 which reported that patients with FTD had significantly shorter survival from estimated onset of symptoms and from initial clinic presentation than did comparable patients with AD. This study also supported our findings that patients with tau pathology had longer survival than those without, and had sufficient patients with ALS-FTD to establish the expected poorer survival in that clinical subgroup. Although there is extensive literature on behavioral changes in FTD, the impact of the disease on functional abilities has not been widely studied. As Dr. Kertesz points out, patients with FTD often neglect hygiene and may have eating disorders such as food crav- ings and difficulty controlling how much and what they eat. How- ever, these and other behavioral changes do not necessarily translate into the loss of functional abilities common to FTD and AD. Our focus on specific activities such as toileting, eating, and dressing allowed us to show that functional decline, which likely adds to the burden (and concern) of a caregiver and “malignancy” of disease, is greater in FTD than in AD. Admittedly, the MMSE is far from ideal for tracking change in FTD. Nevertheless, we believe that our findings should stimulate attempts to develop better ways of detecting cognitive decline in FTD and draw attention to the importance of measuring both instrumental and basic ADL. Furthermore, we hope that our find- ings lead to future research on the relative contributions of cogni- tive decline and behavioral symptoms to functional decline in FTD. David P. Salmon, PhD, Douglas Galasko, MD, Katya Rascovsky, PhD, La Jolla, CA Disclosure: The authors report no conflicts of interest. Copyright © 2006 by AAN Enterprises, Inc. References 1. Rascovsky K, Salmon DP, Lipton AM, et al. Rate of progression differs in frontotemporal dementia and Alzheimer disease. Neurology 2005;65: 397– 403. 2. Kertesz A, McMonagle P, Blair M, et al. The evolution and pathology of frontotemporal dementia. Brain 2005;128:1996 –2005. 3. Roberson ED, Hesse JH, Rose KD, et al. Frontotemporal dementia progresses to death faster than Alzheimer disease. Neurology 2005;65:719 –725. Should the Babinski sign be part of the routine neurologic examination? To the Editor: Drs. Miller and Claiborne Johnston have ne- glected a vital methodologic issue in their efforts to debunk the Babinski sign, 1 an aspect that has also been overlooked by previ- ous detractors. In the Methods section, they describe elaborate measures to eliminate bias, but there is not a word about the criteria for a Babinski sign. The upgoing toe sign is not an oracle, but part of a released withdrawal reflex of the leg. It is often, but not always accompanied by slowed foot tapping, 2 as Drs. Miller and Claiborne Johnston have confirmed. The pathophysiologic background should be considered in the interpretation of the plantar reflex. 3 In brief, the following criteria should be applied: 1) the upgoing toe movement should be caused by contraction of the extensor hallucis longus muscle; 2) the movement should be accompanied by activity in other muscles that shorten the leg; 3) the response should be reproducible. It has been shown in medical students that appli- cation of these criteria improves interobserver agreement. 4 In conclusion, the study of Drs. Miller and Claiborne Johnston was not about the Babinski sign, but about the level of medical education of the physicians who participated in their study. J. van Gijn, MD, FRCP, FRCP(Edin), Utrecht, The Netherlands Disclosure: The author reports no conflicts of interest. To the Editor: The title of Miller and Claiborne Johnston’s arti- cle on the Babinski sign is provocative. 1 The upper motor neuron syndrome (weakness, spasticity, hyperreflexia) may or may not be accompanied by a Babinski sign. The sign itself simply implies a pyramidal tract lesion and may not be associated with any of the upper motor neuron signs that are extrapyramidal in origin, so there is some truth to the statement that it cannot be used to predict weakness. A lesion of the pyramidal tract in isolation results in a flaccid hemiplegia and extensor plantar response both in monkeys when the tract is lesioned in the pyramid and in man when spasticity may follow later, perhaps because the lesion is not “clean”. 5,6 Pseudoscience contaminates the art of the clinical examination, which with experience can be finely honed. Gordon Holmes wrote: “The plantar reflex is so important that the clinician should never May (2 of 2) 2006 NEUROLOGY 66 1607