In particular, however, it is a leading symptom of a number of degenerative conditions: the progressive aphasias ( Mesulam, 1982, Hodges et al., 1992 Mesulam, 2003 Gorno-Tempini et al., 2004). The differential diagnosis of word-finding difficulty therefore encompasses a wide spectrum of acute and chronic disorders as diverse as delirium ( Geschwind, 1964), aphasic stroke ( Kertesz and McCabe, 1977), encephalitis ( Okuda et al., 2001), major depression ( Georgieff et al., 1998) and psychosis ( Critchley, 1964), head injury ( Levin et al., 1976), temporal lobectomy ( Langfitt and Rausch, 1996) and metabolic and genetic disorders ( Spinelli et al., 1995). Furthermore, processing occurs in a distributed network of brain areas that is vulnerable to a variety of acute and chronic pathological states ( Levelt, 1989 Price et al., 1993 Levelt, 2001 Blank et al., 2002 Gorno-Tempini et al., 2004). Spoken communication depends on a sequence of cognitive processes, and disruption of any of these processes can affect word-finding ( Fig. In both situations, the basis for the word-finding problem needs to be established but this is often not straightforward. In many cases, patients will complain of word-finding difficulty or, not uncommonly, the difficulty is identified by the neurologist in the course of the assessment. вЂWord-finding difficultyвЂ™ is a common and challenging problem in neurological practice. We propose a conceptual framework for the analysis of word-finding difficulty, in order both better to define the patient's complaint and its differential diagnosis for the clinician and to identify unresolved issues as a stimulus to future work. We delineate key illustrative speech and language syndromes in the degenerative dementias, compare these syndromes with the syndromes of acute brain damage, and indicate how the clinical syndromes relate to emerging neurolinguistic, neuroanatomical and neurobiological insights. In this review we seek to provide the clinical neurologist with a practical and theoretical bridge between the patient presenting with word-finding difficulty in the clinic and the evidence of the brain sciences.

This has led to a reformulation of our understanding of how language is organized in the brain. Speech and language disturbances in the dementias present unique diagnostic and conceptual problems that are not fully captured by classical models derived from the study of vascular and other acute focal brain lesions.

Recent advances in the neurobiology of the focal, language-based dementias have transformed our understanding of these processes and the ways in which they breakdown in different diseases, but translation of this knowledge to the bedside is far from straightforward. Although it occurs in a variety of clinical contexts, word-finding difficulty generally presents a diagnostic conundrum when it occurs as a leading or apparently isolated symptom, most often as the harbinger of degenerative disease: the progressive aphasias. The complaint of вЂword-finding difficultyвЂ™ covers a wide range of clinical phenomena and may signify any of a number of distinct pathophysiological processes. The patient with word-finding difficulty presents a common and challenging clinical problem.

Voice tends to jumble words