Harrison N. Jones

The emerging phenotype of long-term survivors with infantile Pompe disease

Purpose:Enzyme replacement therapy with alglucosidase alfa for infantile Pompe disease has improved survival creating new management challenges. We describe an emerging phenotype in a retrospective review of long-term survivors.Methods:Inclusion criteria included ventilator-free status and age ≤6 months at treatment initiation, and survival to age ≥5 years. Clinical outcome measures included invasive ventilator-free survival and parameters for cardiac, pulmonary, musculoskeletal, gross motor, and ambulatory status; growth; speech, hearing, and swallowing; and gastrointestinal and nutritional status.Results:Eleven of 17 patients met study criteria. All were cross-reactive immunologic material-positive, alive, and invasive ventilator-free at most recent assessment, with a median age of 8.0 years (range: 5.4–12.0 years). All had marked improvements in cardiac parameters. Commonly present were gross motor weakness, motor speech deficits, sensorineural and/or conductive hearing loss, osteopenia, gastroesophageal reflux, and dysphagia with aspiration risk. Seven of 11 patients were independently ambulatory and four required the use of assistive ambulatory devices. All long-term survivors had low or undetectable anti-alglucosidase alfa antibody titers.Conclusion:Long-term survivors exhibited sustained improvements in cardiac parameters and gross motor function. Residual muscle weakness, hearing loss, risk for arrhythmias, hypernasal speech, dysphagia with risk for aspiration, and osteopenia were commonly observed findings.Genet Med 2012:14(9):800–810.

Expanding the phenotype of late-onset pompe disease: Tongue weakness: A new clinical observation

Introduction: Following the clinical observation of lingual weakness in 2 patients with late‐onset Pompe disease (LOPD), tongue strength was assessed in 19 consecutive patients to determine the frequency and severity of this neurological sign. Methods: Lingual strength was assessed using manual muscle testing; if weakness was present, severity was established as mild, moderate, or severe. Results: All the patients exhibited lingual weakness, even 2 asymptomatic patients with a positive family history. Weakness was mild in 12 (63%), moderate in 6 (32%), and severe in 1 (5%). Dysarthria and/or dysphagia were observed or reported in 7 of 19 (37%) patients. Conclusions: Lingual weakness may be present as an axial sign of LOPD, even relatively early in the disease course, and may contribute to the differential diagnosis of this now treatable condition. Dysphagia and/or dysarthria may also occur. This finding further expands the phenotype of LOPD. Muscle Nerve, 2011

Oropharyngeal dysphagia may occur in late-onset Pompe disease, implicating bulbar muscle involvement

Late-onset Pompe disease (presenting after 12 months of age) often presents with limb-girdle and respiratory weakness, but oropharyngeal dysphagia has not been reported previously. A retrospective review of all late-onset Pompe disease patients evaluated in the neuromuscular clinic at Duke University Medical Center from 1999-2010 was performed. Twelve patients were identified and 3 had symptoms of oropharyngeal dysphagia. The medical record was reviewed, including the results of electromyography, videofluroscopic swallow examinations, and motor speech examination including instrumental assessment of lingual force with the Iowa Oral Performance Instrument. Oropharyngeal dysphagia was mild in two cases and severe in one. One of the two patients with mild severity demonstrated oral stage swallow signs; in the other, residual material was observed in the area of the cervical esophagus. In the patient with severe oropharyngeal dysphagia, both the oral and pharyngeal stages of swallowing were affected with penetration and aspiration documented. The degree of swallowing impairment appeared to correlate with overall physical strength and function. Oropharyngeal dysphagia may occur in patients with late-onset Pompe disease, implicating bulbar muscle involvement. Screening for symptoms of dysphagia may help reduce morbidity and mortality, while improving understanding of the late-onset Pompe disease phenotype. Further studies, including examination of the relationship between lingual weakness and oropharyngeal dysphagia, are warranted.

The emerging phenotype of late-onset Pompe disease: A systematic literature review

BACKGROUND Pompe disease is an autosomal recessive disorder caused by deficiency of the lysosomal glycogen-hydrolyzing enzyme acid α-glucosidase (GAA). The adult-onset form, late-onset Pompe disease (LOPD), has been characterized by glycogen accumulation primarily in skeletal, cardiac, and smooth muscles, causing weakness of the proximal limb girdle and respiratory muscles. However, increased scientific study of LOPD continues to enhance understanding of an evolving phenotype. PURPOSE To expand our understanding of the evolving phenotype of LOPD since the approval of enzyme replacement therapy (ERT) with alglucosidase alfa (Myozyme™/Lumizyme™) in 2006. METHODS All articles were included in the review that provided data on the charactertistics of LOPD identified via the PubMed database published since the approval of ERT in 2006. All signs and symptoms of the disease that were reported in the literature were identified and included in the review. RESULTS We provide a comprehensive review of the evolving phenotype of LOPD. Our findings support and extend the knowledge of the multisystemic nature of the disease. CONCLUSIONS With the advent of ERT and the concurrent increase in the scientific study of LOPD, the condition once primarily conceptualized as a limb-girdle muscle disease with prominent respiratory involvement is increasingly recognized to be a condition that results in signs and symptoms across body systems and structures.

Increased inspiratory and expiratory muscle strength following respiratory muscle strength training (RMST) in two patients with late-onset Pompe disease

Respiratory muscle strength training (RMST) is an exercise-based intervention which targets respiratory muscle weakness. We implemented RMST in two patients with late-onset Pompe disease (LOPD), both who had received long-term enzyme replacement therapy and had severe respiratory weakness. Over 16-32 weeks, inspiratory muscle strength increased by 73-74%. Expiratory muscle strength increased 31-48% over 12-22 weeks. These findings suggest that RMST may increase respiratory muscle strength, even in the setting of LOPD and severe baseline weakness.

Language and speech function in children with infantile Pompe disease

Pompe disease, also known as glycogen storage disease type II and acid maltase deficiency, is a rare autosomal recessive progressive neuromuscular disorder. The natural course of the infantile form of this condition has resulted in mortality for patients prior to 1 year of age, making investigations into language and speech function in this population impossible. However, with the advent of treatment with enzyme replacement therapy (ERT) using alglucosidase alfa (Myozyme ), the lifespan of children with this condition has been extended. A retrospective study of the language and speech skills of 12 children enrolled in clinical trials for treatment with ERT at a tertiary care center was completed. Standardized language assessment instruments were administered to all participants, and six of the 12 were assessed twice. At initial assessment, overall language function was found to be age appropriate in 58% of participants, while, in those who received reassessment, overall normal language function was seen in 83%. Speech assessments were completed during all visits in which subjects were 24 months or older. Articulatory disorders and/or hypernasality were commonly encountered and were exhibited in 82% of speech assessments. Disorders in language and/or speech were found in all participants at some point in the course of the study. Overall, language delays tended to improve with time. Speech disorders were encountered more commonly, were often severe, and appeared to be motoric in nature. Children with infantile Pompe disease treated with ERT appear to be at high risk for speech disorders in particular. Further systematic investigations are needed.

Correlation between quantitative whole-body muscle magnetic resonance imaging and clinical muscle weakness in pompe disease

Previous examination of whole‐body muscle involvement in Pompe disease has been limited to physical examination and/or qualitative magnetic resonance imaging (MRI). In this study we assess the feasibility of quantitative proton‐density fat‐fraction (PDFF) whole‐body MRI in late‐onset Pompe disease (LOPD) and compare the results with manual muscle testing.

Multidisciplinary assessment and diagnosis of conversion disorder in a patient with foreign accent syndrome

Multiple reports have described patients with disordered articulation and prosody, often following acute aphasia, dysarthria, or apraxia of speech, which results in the perception by listeners of a foreign-like accent. These features led to the term foreign accent syndrome (FAS), a speech disorder with perceptual features that suggest an indistinct, non-native speaking accent. Also correctly known as psuedoforeign accent, the speech does not typically match a specific foreign accent, but is rather a constellation of speech features that result in the perception of a foreign accent by listeners. The primary etiologies of FAS are cerebrovascular accidents or traumatic brain injuries which affect cortical and subcortical regions critical to expressive speech and language production. Far fewer cases of FAS associated with psychiatric conditions have been reported. We will present the clinical history, neurological examination, neuropsychological assessment, cognitive-behavioral and biofeedback assessments, and motor speech examination of a patient with FAS without a known vascular, traumatic, or infectious precipitant. Repeated multidisciplinary examinations of this patient provided convergent evidence in support of FAS secondary to conversion disorder. We discuss these findings and their implications for evaluation and treatment of rare neurological and psychiatric conditions.

Respiratory muscle training (RMT) in late-onset Pompe disease (LOPD): Effects of training and detraining.

BACKGROUND Determine the effects of a 12-week respiratory muscle training (RMT) program in late-onset Pompe disease (LOPD). METHODS We investigated the effects of 12-weeks of RMT followed by 3-months detraining using a single-subject A-B-A experimental design replicated across 8 adults with LOPD. To assess maximal volitional respiratory strength, our primary outcomes were maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP). Effect sizes for changes in MIP and MEP were determined using Cohens d statistic. Exploratory outcomes targeted motor function, and peak cough flow (PCF) was measured in the last 5 subjects. RESULTS From pretest to posttest, all 8 subjects exhibited increases in MIP, and 7 of 8 showed increases in MEP. Effect size data reveal the magnitude of increases in MIP to be large in 4 (d≥1.0) and very large in 4 (d≥2.0), and effect sizes for increases in MEP were large in 1 (d≥1.0) and very large in 6 (d≥2.0). Across participants, pretest to posttest MIP and MEP increased by a mean of 19.6% (sd=9.9) and 16.1% (sd=17.3), respectively. Respiratory strength increases, particularly for the inspiratory muscles, were generally durable to 3-months detraining. CONCLUSIONS These data suggest our 12-week RMT program results in large to very large increases in inspiratory and expiratory muscle strength in adults with LOPD. Additionally, increases in respiratory strength appeared to be relatively durable following 3-months detraining. Although additional research is needed, RMT appears to offer promise as an adjunctive treatment for respiratory weakness in LOPD.

Early cognitive development in children with infantile Pompe disease

This report describes the cognitive development of 17 children with infantile Pompe disease who participated in a 52-week clinical trial of enzyme replacement therapy (ERT) via biweekly infusion of Myozyme® (alglucosidase alfa). Subjects were six months of age or younger (adjusted for gestational age) upon initiation of ERT. The Mental Scale of the Bayley Scales of Infant Development-Second Edition (BSID-II) was administered to obtain a Mental Development Index (MDI) at baseline and weeks 12, 26, 38, and 52 of ERT to assess cognitive development in this treated cohort. Data regarding motor development were also obtained at the same visits and these were used to determine correlations between cognitive and motor development. Over the course of the study, two subgroups of subjects emerged: high responders who were sitting independently and/or ambulating by week 52 (n=13) and limited responders who showed minimal motor gains throughout the first year of ERT (n=4). In the high responder group, MDI scores on the BSID-II remained stable throughout the study and were within normal limits. Positive correlations between cognitive and motor development were also present. These data suggest that the cognitive function of infants up to 18 months of age with Pompe disease is unaffected by the possible presence of glycogen in the central nervous system. Continued investigation of the cognitive development of older survivors is warranted.