Biologia Molecular

J Inherit Metab Dis (2011) 34:377–385 DOI 10.1007/s10545-010-9213-4

GALACTOSEMIA

Voice disorders in children with classic galactosemia
Nancy L. Potter

Received: 3 July 2010 / Revised: 27 August 2010 / Accepted: 8 September 2010 / Published online: 30 September 2010 # SSIEM and Springer 2010

Abstract Children with classic galactosemia are at risk for motor speech disorders resulting fromdisruptions in motor planning and programming (childhood apraxia of speech or CAS) or motor execution (dysarthria). In the present study of 33 children with classic galactosemia, 21% were diagnosed with CAS, 3% with ataxic dysarthria, and 3% with mixed CAS-dysarthria. Voice disorders due to laryngeal insufficiency were common in children with dysarthria and co-occurred with CAS. Most (58%) of thechildren with classic galactosemia had decreased respiratory-phonatory support for speech, and 33% had disturbed vocal quality that was indicative of cerebellar dysfunction. Three children, two diagnosed with CAS and one not diagnosed with a motor speech disorder, had vocal tremors. Treatment of voice dysfunction in neurogenic speech disorders is discussed. Abbreviations CAS Childhood apraxia of speechGAL-MSD Individuals with classic galactosemia diagnosed with a motor speech disorder GAL Individuals with classic galactosemia not diagnosed with a motor speech disorder LSVT Lee Silverman voice treatment program OWLS Oral and written language scale MSD Motor speech disorder

Introduction Galactosemia and speech disorders Classic galactosemia (shortened to galactosemia in the present paper) is arecessive inborn error of metabolism characterized by defective conversion of galactose to glucose, due to a near absence of the enzyme galactose-1phosphate uridyl transferase. This enzyme deficiency leads to an accumulation of toxic metabolites. In many patients with galactosemia, abnormalities of myelinization are found in the cerebral hemispheres and cerebellum (Phelan et al. 2008). Despiteearly detection and adherence to lactoserestricted diets, speech disorders affect more than half of children with galactosemia (Nelson et al. 1991; Waggoner et al. 1990; Waisbren et al. 1983; Webb et al. 2003). Most studies have used the diagnostic term developmental verbal dyspraxia to refer to the type of speech disorder reported to occur in 35–77% of children with galactosemia (Hughes et al. 2009;Nelson et al. 1991; Robertson et al. 2000; Webb et al. 2003). The term developmental verbal dyspraxia has recently been replaced with childhood apraxia of speech (CAS; American Speech-Language-Hearing Association 2007) and will be used in this paper. CAS is a type of motor speech disorder (MSD). Motor speech disorders are a category of speech disorders caused by disruptions in higher-level motorcommands, neuromuscular system impairments, or both (Duffy 2005). CAS is characterized by (1) inconsistent consonant and vowel errors, (2) difficulty transitioning between articulatory movements, and (3) inappropriate prosody during speech (American Speech-Language-Hearing Association 2007). In adults, apraxia may result from a disruption in higher-level motor commands primarily in the lefthemisphere Broca’s area, supplementary motor area, or insula and may involve the

Communicated by: Estela Rubio Competing interest: None declared N. L. Potter (*) Department of Speech and Hearing Sciences, Washington State University-Spokane, PO Box 1495, Spokane, WA 99210-1495, USA e-mail: nlpotter@wsu.edu

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cerebellum and basal ganglia leading to difficultyin planning and programming the sequence of speech movements. The neurobiological basis of CAS is not yet known (Terband and Maassen 2010). Currently, there is no accepted “gold standard” assessment instrument for diagnosing CAS, resulting in variability in diagnostic prevalence across studies. CAS often is confused with, or co-presents with, another type of MSD, dysarthria, infrequently...