Speech and Language Disorders Associated with Corticobasal Degeneration
Blake, Margaret Lehman, Duffy, Joseph R., Boeve, Bradley F., Ahlskog, Eric J., Maraganore, Demetrius M., Journal of Medical Speech - Language Pathology
Corticobasal degeneration (CBD) is a neurodegenerative disease characterized by asymmetric cortical and extrapyramidal signs including progressive asymmetric limb rigidity and apraxia. Other commonly occurring signs include alien limb phenomena, frontal release signs, postural instability, cognitive and/or memory deficits, aphasia, apraxia of speech, and dysarthria. An extensive literature review revealed that although speech and language deficits are common, they rarely are described in detail. The current study examined the speech and language characteristics of 13 cases of autopsy-confirmed CBD. Findings indicate that speech and language disorders were common signs of the disorder and often were among the first signs of CBD. Aphasia was present in over half of the patients and was most often characterized as nonfluent, or anomic. Dysarthria and apraxia of speech were present in approximately 30% and 40% of patients, respectively. Dysarthria type was typically mixed, with either spastic or hypokinetic features present in all affected cases. Although the presentation of speech and language disorders was heterogeneous across patients, the findings highlight the importance of these disorders in the detection and diagnosis of CBD.
Degenerative neurological disorders frequently result in speech and language deficits, including dysarthria, apraxia of speech (AOS), and aphasia. These deficits may be the first sign of a degenerative neurological condition, and their recognition can contribute to the localization of pathologic changes and the neurologic diagnosis (Duffy, 1995).
Corticobasal degeneration (CBD; also called cortico-basal-ganglionic degeneration or cortico-striatal-nigral degeneration) * is a neurodegenerative disease characterized by asymmetric cortical and extrapyramidal signs, often with progressive asymmetric limb rigidity and apraxia as the core syndrome. Clinical diagnosis of probable CBD or CBD syndrome is made when these signs are present and do not respond to drugs used to treat Parkinson disease, such as levodopa. Other common signs that may appear during the course of CBD include alien limb phenomena, aphasia, apraxia of speech, dysarthria, cognitive and/or memory deficits, frontal release signs, and postural instability (Boeve et al., 2000; Kompoliti et al., 1998; Lang, Riley, & Bergeron, 1994; Litvan, 1997; Litvan et al., 1997; Rinne, Lee, Thompson, & Marsden, 1994). Symptoms usually appear insidiously in the sixth to eighth decade, with gradual progression over 5 to 15 years until death (Boeve, 2000; Muller et. al., 2001).
Characteristics of the speech and language deficits that may occur in CBD are not well described, although they commonly are commented on. In a literature review conducted by searching the Medline database from 1990 to April 2000 using the keyword "corticobasal degeneration," 66 reports were identified that provided behavioral descriptions of a total of 504 cases, the majority of which had clinically diagnosed CBD (as opposed to biopsy or autopsy-confirmed CBD). Speech or language characteristics were described in 60 of the 66 articles, representing 457 of the 504 cases. Twelve cases were known to be duplicated in multiple articles (Frattali, Grafman, Patronas, Makhlouf, & Litvan, 2000; Frattali & Sonies, 2000), and thus were counted only once in the total, leaving 457. Table 1 summarizes the speech and language problems noted within these 60 articles.
Speech disorders (i.e., dysarthria or AOS) were identified in 55% of the 457 cases (253/457). Diagnoses of these disorders were made by neurologists in the majority of cases and by a speech-language pathologist in 26 cases. Dysarthria was reported in 191 patients (42% of the 457 cases) within 34 of the 60 articles. Dysarthria--type using Darley, Aronson, and Brown's (1975) method of categorization--was reported in only one study. In that study, Frattali and Sonies (2000) identified hypokinetic dysarthria in 5 of their 13 patients, mixed dysarthria in 7 patients, and spastic dysarthria in 1 patient. …