Nemaline myopathy (referred to in this entry as NM) is characterized by weakness, hypotonia, and ... more Nemaline myopathy (referred to in this entry as NM) is characterized by weakness, hypotonia, and depressed or absent deep tendon reflexes. Muscle weakness is usually most severe in the face, the neck flexors, and the proximal limb muscles. Six forms of NM exist, classified by onset and severity of motor and respiratory involvement: Considerable overlap occurs among the forms. Significant differences in survival exist between individuals classified as having severe, intermediate, and typical congenital NM. Severe neonatal respiratory disease and the presence of arthrogryposis multiplex congenita are associated with death in the first year of life. Independent ambulation before age 18 months is predictive of survival. Most children with typical congenital NM are eventually able to walk. Diagnosis is based on clinical findings and the observation of characteristic rod-shaped structures (nemaline bodies) on muscle biopsy stained with Gomori trichrome. Disease-causing mutations have been...
Episodic myalgia is a common complaint in children and young adults. While many cases remain idio... more Episodic myalgia is a common complaint in children and young adults. While many cases remain idiopathic even after extensive investigation, myalgia can be the first symptom of an underlying serious neuromuscular condition, and can be associated with an increased risk of such serious complications as rhabdomyolysis and malignant hyperthermia. We review and highlight the metabolic myopathies and other increasingly recognised muscle disorders that may present to paediatricians with episodic myalgia or isolated episodes of rhabdomyolysis, and propose a diagnostic algorithm for investigation of these complaints.
The Aristaless-related homeobox (ARX) gene is implicated in intellectual disability with the most... more The Aristaless-related homeobox (ARX) gene is implicated in intellectual disability with the most frequent pathogenic mutations leading to expansions of the first two polyalanine tracts. Here, we describe analysis of the ARX gene outlining the approaches in the Australian and Portuguese setting, using an integrated clinical and molecular strategy. We report variants in the ARX gene detected in 19 patients belonging to 17 families. Seven pathogenic variants, being expansion mutations in both polyalanine tract 1 and tract 2, were identifyed, including a novel mutation in polyalanine tract 1 that expands the first tract to 20 alanines. This precise number of alanines is sufficient to cause pathogenicity when expanded in polyalanine tract 2. Five cases presented a probably non-pathogenic variant, including the novel HGVS: c.441_455del, classified as unlikely disease causing, consistent with reports that suggest that in frame deletions in polyalanine stretches of ARX rarely cause intellectual disability. In addition, we identified five cases with a variant of unclear pathogenic significance. Owing to the inconsistent ARX variants description, publications were reviewed and ARX variant classifications were standardized and detailed unambiguously according to recommendations of the Human Genome Variation Society. In the absence of a pathognomonic clinical feature, we propose that molecular analysis of the ARX gene should be included in routine diagnostic practice in individuals with either nonsyndromic or syndromic intellectual disability. A definitive diagnosis of ARX-related disorders is crucial for an adequate clinical follow-up and accurate genetic counseling of at-risk family members.
The delayed diagnosis of Duchenne muscular dystrophy (DMD) may be an ongoing problem internationa... more The delayed diagnosis of Duchenne muscular dystrophy (DMD) may be an ongoing problem internationally. We aimed to ascertain age at diagnosis and explore parents' experiences of the diagnosis of DMD in Australia. Using mixed methods, data were collected from laboratory and clinical record audits of testing for DMD in Victoria and Tasmania, interviews and a national survey of parents regarding their experiences from first noticing symptoms to receiving a diagnosis. The audits revealed that the median age at diagnosis for DMD was 5 years (n=49 during 2005-2010); this age had not changed substantially over this period. Fourteen parents interviewed reported age at diagnosis ranging from 2 to 8 years with a 6 month to 4 year delay between initial concerns about their child's development and receiving the DMD diagnosis. Sixty-two survey respondents reported the median age at diagnosis was 3 years and 9 months, while the median age when symptoms were noticed was 2 years and 9 months. Parents experienced many emotions in their search for a diagnosis and consulted with a wide range of health professionals. Half the survey respondents felt that their child could have been diagnosed earlier. Despite advances in testing technologies and increasing awareness of DMD, the age at diagnosis has remained constant in Australia. This mixed methods study shows that this diagnostic delay continues to have a negative impact on parents' experiences, places families at risk of having a second affected child and may have a deleterious effect on affected children's treatment.European Journal of Human Genetics advance online publication, 28 January 2015; doi:10.1038/ejhg.2014.301.
Charcot-Marie-Tooth disease type 1A (CMT1A), a demyelinating neuropathy characterised by progress... more Charcot-Marie-Tooth disease type 1A (CMT1A), a demyelinating neuropathy characterised by progressive length-dependent muscle weakness and atrophy, is thought to affect the foot and leg first followed some time later by hand weakness and dysfunction. We aimed to characterise hand strength, function and disease-related symptoms in children with CMT1A. Intrinsic and extrinsic hand strength was measured by hand-held dynamometry, function by nine-hole peg test, and disease-related symptoms by interview and examination in 84 affected children aged 2-16 years. Hand weakness and dysfunction was present from the earliest stages of the disease. While hand strength and function measures tended to increase with age throughout childhood, at no point did they reach normal values. Day-to-day hand problems such as poor handwriting, weakness, pain and sensory symptoms also worsened with age. The hand is affected at all ages in children with CMT1A, but may be under-recognised in its early stages, potentially delaying therapy.
The inherited myopathies and muscular dystrophies are a diverse group of muscle diseases presenti... more The inherited myopathies and muscular dystrophies are a diverse group of muscle diseases presenting with common complaints and physical signs: weakness, motor delay, and respiratory and bulbar dysfunction. The myopathies are caused by genetic defects in the contractile apparatus of muscle, and defined by distinctive histochemical or ultrastructural changes on muscle biopsy. The muscular dystrophies, in contrast, are diseases of muscle membrane or supporting proteins, which are generally characterized by pathological evidence of ongoing muscle degeneration and regeneration. Diagnosis of these disorders is contingent on a targeted history and examination, biochemical and neurophysiological assessment, muscle biopsy, and genetic testing. Treatment is focused on symptomatic management and rehabilitation, and monitoring for disease complications.
To date, fewer than 30 cases of anterior horn cell disease with associated olivopontocerebellar h... more To date, fewer than 30 cases of anterior horn cell disease with associated olivopontocerebellar hypoplasia have been reported. We describe five patients and review the literature on this uncommon disorder. In addition to a syndrome of progressive spinal muscular atrophy similar to that seen in Werdnig-Hoffmann disease, this disorder is characterised by hypoplasia of the olivary nuclei, pons, and cerebellum. Additional clinical features may include dysmorphism, abnormal eye movements, stridor, congenital joint contractures, and enlarged kidneys. Pontocerebellar hypoplasia may be associated with posterior fossa cystic malformations, cerebral atrophy, and a demyelinating neuropathy.
Curcumin is the newest therapeutic agent for ameliorating the clinical and neuropathologic phenot... more Curcumin is the newest therapeutic agent for ameliorating the clinical and neuropathologic phenotype of a mouse model of Déjérine-Sottas disease. We undertook a 12-month dose-escalation safety trial of oral curcumin in a 15-year-old Caucasian girl with Déjérine-Sottas disease (point mutation, Ser72Leu) complicated by severe weakness, scoliosis, and respiratory impairment. The patient received 50 mg/kg/day oral curcumin for the first 4 months and 75 mg/kg/day thereafter, to complete a 12-month trial. Outcome measures included muscle strength, pulmonary function, upper/lower extremity disability, neurophysiologic studies, and health-related quality of life. After 12 months, the patient experienced no adverse events, and reported good compliance. There was little improvement in objective outcome measures. Knee flexion and foot strength increased slightly, but hand and elbow strength decreased. Pulmonary function, hand function, and measures of upper/lower extremity disability were stable or reduced. Her neurophysiologic findings were unchanged. Parent-reported quality of life improved for most domains, especially self-esteem, during the 12 months of treatment. Child-reported quality of life, assessed at the final visit, mirrored these results, with overall feelings of happiness and contentment. Further studies are required to explore the efficacy and safety of curcumin for severe demyelinating neuropathies of infancy and early childhood.
The X-linked Charcot-Marie-Tooth disease is the second most common form of inherited neuropathy a... more The X-linked Charcot-Marie-Tooth disease is the second most common form of inherited neuropathy and, unlike most other forms of this disease, may present with atypical manifestations because of central nervous system involvement. Episodic central nervous system symptoms in X-linked Charcot-Marie-Tooth disease may be triggered by illness, dehydration, physical exercise, or exposure to altitude. We describe a child with transient episodes of hemiplegia after simple hyperventilation, a presentation not previously described in pediatric Charcot-Marie-Tooth disease type X.
A 14-year-old boy presented with acute paraparesis with sensory and sphincter disturbance. Imagin... more A 14-year-old boy presented with acute paraparesis with sensory and sphincter disturbance. Imaging and neurophysiologic studies were diagnostic for transverse myelitis with acute motor axonal neuropathy. He was treated with both intravenous immunoglobulin and high-dose corticosteroids, and he made a slow and incomplete recovery. Acute motor axonal neuropathy is an unusual variant of Guillain-Barré syndrome. Concomitant transverse myelitis and acute motor axonal neuropathy were not previously reported in childhood, although there are reports of coexisting transverse myelitis and other variants of Guillain-Barré syndrome. Such dual lower motor neuron pathology may be associated with a poorer outcome, and indicates simultaneous central and peripheral immune-mediated injury. There may be a place for combined therapy with immunoglobulin and corticosteroids in patients with transverse myelitis and inflammatory neuropathy.
A young adult male with cardiofaciocutaneous syndrome developed gait deterioration in childhood, ... more A young adult male with cardiofaciocutaneous syndrome developed gait deterioration in childhood, with later evolution of distal wasting. His physical examination revealed intention tremor, distal weakness of the upper limbs with atrophy of the thenar, hypothenar, and interossei muscles, a wide-based gait, and largefiber sensory loss in all limbs. Neuroimaging revealed stable mild chronic communicating hydrocephalus. Nerve conduction studies and electromyography demonstrated a moderately severe axonal neuropathy. The present case is, to our knowledge, the first reported case of peripheral neuropathy in association with cardiofaciocutaneous syndrome. The latter is a rare disorder, with significant comorbidities, in which a peripheral neuropathy may be under-recognized as a late cause of functional deterioration.
Autoimmune myasthenia gravis is a rare condition in children. Identifying antibodies directed aga... more Autoimmune myasthenia gravis is a rare condition in children. Identifying antibodies directed against the acetylcholine receptor is helpful in making the diagnosis. However, seronegative cases do exist and need to be distinguished from congenital forms of myasthenia. There is little published experience to inform the judicious management of autoimmune myasthenia gravis in children. In this article, we report our experience in the management of 12 cases of autoimmune myasthenia gravis in children in the modern era of medical immunotherapy and thymectomy. Crown
Objectives: To identify correlates of calf cramp in children with Charcot-Marie-Tooth disease typ... more Objectives: To identify correlates of calf cramp in children with Charcot-Marie-Tooth disease type 1A (CMT1A).
Pes cavus in Charcot-Marie-Tooth disease type 1A (CMT1A) is thought to be due to muscle imbalance... more Pes cavus in Charcot-Marie-Tooth disease type 1A (CMT1A) is thought to be due to muscle imbalance of the lower leg. Botulinum toxin type A (BoNT-A) can modify foot deformity in other conditions of muscle imbalance. We tested the safety and effectiveness of BoNT-A on pes cavus progression in pediatric CMT1A. A 24-month, randomized, single-blind trial of BoNT-A was undertaken in 10 affected children (20 legs), aged 3-14 years. The treated leg received intramuscular BoNT-A injections at 6-month intervals in the tibialis posterior and peroneus longus. The control leg received no injections. Primary outcome was radiographic alignment at 24 months. Secondary outcomes were foot posture, ankle flexibility, and strength, assessed every 6 months. Radiographically, BoNT-A produced a small non-significant reduction in cavus progression. There was no effect of BoNT-A on secondary outcomes. There were no serious adverse events. At 24 months, the intramuscular BoNT-A injections proved safe and well-tolerated but did not affect the progression of pes cavus in CMT1A.
Spinal muscular atrophy (SMA) is generally associated with proximal weakness and muscle wasting. ... more Spinal muscular atrophy (SMA) is generally associated with proximal weakness and muscle wasting. An X-linked variant with calf hypertrophy has been reported. We describe a young man with SMA type 4 with prominent calf hypertrophy in whom DNA analysis showed a homozygous deletion of exons 7 and 8 in the telomeric copy of the survival motor neuron gene. Calf hypertrophy may be seen uncommonly in autosomally inherited SMA.
We studied the timing and progression of foot and ankle changes in 81 children with genetically c... more We studied the timing and progression of foot and ankle changes in 81 children with genetically confirmed Charcot-Marie-Tooth disease type 1A (CMT1A) and determined their impact on motor function and walking ability. Foot deformity, weakness, pain, cramps, and instability were a common feature of CMT1A. Foot structure evolved toward pes cavus from early childhood to adolescence, although a subgroup with normal and planus feet remained. Foot strength increased with age, although compared to age-equivalent norms it declined from 4 years. Factors associated with evolving foot deformity included muscle weakness/imbalance, restricted ankle flexibility, and joint hypermobility. Regression modeling identified dorsiflexion weakness, global foot weakness, and difficulty toe-walking as independent predictors of motor dysfunction, while pes cavus and difficulty heel-walking were predictors of poor walking ability. Foot problems are present from the earliest stages of the disease and can have a negative impact on function. Early foot and ankle intervention may prevent long-term disability and morbidity in CMT1A.
Preschool-age children with neuromuscular disorders are often excluded from clinical trials due t... more Preschool-age children with neuromuscular disorders are often excluded from clinical trials due to the lack of reliable and objective strength measures. We evaluated the reliability of measuring foot and ankle muscle strength in 60 healthy children age 2-4 years. The strength of foot inversion and eversion, ankle plantarflexion, and dorsiflexion was measured using a hand-held dynamometer. Intrarater and interrater reliability of two assessors was determined for each muscle group using intraclass correlation coefficients (ICCs), 95% confidence intervals (CIs), and standard error of measurement (SEM). For all muscle groups intrarater (ICC(2,2) = 0.85-0.94, 95% CI = 0.75-0.96, SEM = 1.5-4.7 N) and interrater (ICC(2,1) = 0.88-0.96, 95% CI = 0.81-0.98, SEM = 1.2-4.6 N) reliability was high for all children. As expected, reliability was generally highest in 3- and 4-year-old children and lowest in 2-year-old children. Hand-held dynamometry can reliably measure foot and ankle strength in very young children and may help aid in diagnosis and in characterizing disease progression in disorders affecting the foot and ankle.
Nemaline myopathy (referred to in this entry as NM) is characterized by weakness, hypotonia, and ... more Nemaline myopathy (referred to in this entry as NM) is characterized by weakness, hypotonia, and depressed or absent deep tendon reflexes. Muscle weakness is usually most severe in the face, the neck flexors, and the proximal limb muscles. Six forms of NM exist, classified by onset and severity of motor and respiratory involvement: Considerable overlap occurs among the forms. Significant differences in survival exist between individuals classified as having severe, intermediate, and typical congenital NM. Severe neonatal respiratory disease and the presence of arthrogryposis multiplex congenita are associated with death in the first year of life. Independent ambulation before age 18 months is predictive of survival. Most children with typical congenital NM are eventually able to walk. Diagnosis is based on clinical findings and the observation of characteristic rod-shaped structures (nemaline bodies) on muscle biopsy stained with Gomori trichrome. Disease-causing mutations have been...
Episodic myalgia is a common complaint in children and young adults. While many cases remain idio... more Episodic myalgia is a common complaint in children and young adults. While many cases remain idiopathic even after extensive investigation, myalgia can be the first symptom of an underlying serious neuromuscular condition, and can be associated with an increased risk of such serious complications as rhabdomyolysis and malignant hyperthermia. We review and highlight the metabolic myopathies and other increasingly recognised muscle disorders that may present to paediatricians with episodic myalgia or isolated episodes of rhabdomyolysis, and propose a diagnostic algorithm for investigation of these complaints.
The Aristaless-related homeobox (ARX) gene is implicated in intellectual disability with the most... more The Aristaless-related homeobox (ARX) gene is implicated in intellectual disability with the most frequent pathogenic mutations leading to expansions of the first two polyalanine tracts. Here, we describe analysis of the ARX gene outlining the approaches in the Australian and Portuguese setting, using an integrated clinical and molecular strategy. We report variants in the ARX gene detected in 19 patients belonging to 17 families. Seven pathogenic variants, being expansion mutations in both polyalanine tract 1 and tract 2, were identifyed, including a novel mutation in polyalanine tract 1 that expands the first tract to 20 alanines. This precise number of alanines is sufficient to cause pathogenicity when expanded in polyalanine tract 2. Five cases presented a probably non-pathogenic variant, including the novel HGVS: c.441_455del, classified as unlikely disease causing, consistent with reports that suggest that in frame deletions in polyalanine stretches of ARX rarely cause intellectual disability. In addition, we identified five cases with a variant of unclear pathogenic significance. Owing to the inconsistent ARX variants description, publications were reviewed and ARX variant classifications were standardized and detailed unambiguously according to recommendations of the Human Genome Variation Society. In the absence of a pathognomonic clinical feature, we propose that molecular analysis of the ARX gene should be included in routine diagnostic practice in individuals with either nonsyndromic or syndromic intellectual disability. A definitive diagnosis of ARX-related disorders is crucial for an adequate clinical follow-up and accurate genetic counseling of at-risk family members.
The delayed diagnosis of Duchenne muscular dystrophy (DMD) may be an ongoing problem internationa... more The delayed diagnosis of Duchenne muscular dystrophy (DMD) may be an ongoing problem internationally. We aimed to ascertain age at diagnosis and explore parents' experiences of the diagnosis of DMD in Australia. Using mixed methods, data were collected from laboratory and clinical record audits of testing for DMD in Victoria and Tasmania, interviews and a national survey of parents regarding their experiences from first noticing symptoms to receiving a diagnosis. The audits revealed that the median age at diagnosis for DMD was 5 years (n=49 during 2005-2010); this age had not changed substantially over this period. Fourteen parents interviewed reported age at diagnosis ranging from 2 to 8 years with a 6 month to 4 year delay between initial concerns about their child's development and receiving the DMD diagnosis. Sixty-two survey respondents reported the median age at diagnosis was 3 years and 9 months, while the median age when symptoms were noticed was 2 years and 9 months. Parents experienced many emotions in their search for a diagnosis and consulted with a wide range of health professionals. Half the survey respondents felt that their child could have been diagnosed earlier. Despite advances in testing technologies and increasing awareness of DMD, the age at diagnosis has remained constant in Australia. This mixed methods study shows that this diagnostic delay continues to have a negative impact on parents' experiences, places families at risk of having a second affected child and may have a deleterious effect on affected children's treatment.European Journal of Human Genetics advance online publication, 28 January 2015; doi:10.1038/ejhg.2014.301.
Charcot-Marie-Tooth disease type 1A (CMT1A), a demyelinating neuropathy characterised by progress... more Charcot-Marie-Tooth disease type 1A (CMT1A), a demyelinating neuropathy characterised by progressive length-dependent muscle weakness and atrophy, is thought to affect the foot and leg first followed some time later by hand weakness and dysfunction. We aimed to characterise hand strength, function and disease-related symptoms in children with CMT1A. Intrinsic and extrinsic hand strength was measured by hand-held dynamometry, function by nine-hole peg test, and disease-related symptoms by interview and examination in 84 affected children aged 2-16 years. Hand weakness and dysfunction was present from the earliest stages of the disease. While hand strength and function measures tended to increase with age throughout childhood, at no point did they reach normal values. Day-to-day hand problems such as poor handwriting, weakness, pain and sensory symptoms also worsened with age. The hand is affected at all ages in children with CMT1A, but may be under-recognised in its early stages, potentially delaying therapy.
The inherited myopathies and muscular dystrophies are a diverse group of muscle diseases presenti... more The inherited myopathies and muscular dystrophies are a diverse group of muscle diseases presenting with common complaints and physical signs: weakness, motor delay, and respiratory and bulbar dysfunction. The myopathies are caused by genetic defects in the contractile apparatus of muscle, and defined by distinctive histochemical or ultrastructural changes on muscle biopsy. The muscular dystrophies, in contrast, are diseases of muscle membrane or supporting proteins, which are generally characterized by pathological evidence of ongoing muscle degeneration and regeneration. Diagnosis of these disorders is contingent on a targeted history and examination, biochemical and neurophysiological assessment, muscle biopsy, and genetic testing. Treatment is focused on symptomatic management and rehabilitation, and monitoring for disease complications.
To date, fewer than 30 cases of anterior horn cell disease with associated olivopontocerebellar h... more To date, fewer than 30 cases of anterior horn cell disease with associated olivopontocerebellar hypoplasia have been reported. We describe five patients and review the literature on this uncommon disorder. In addition to a syndrome of progressive spinal muscular atrophy similar to that seen in Werdnig-Hoffmann disease, this disorder is characterised by hypoplasia of the olivary nuclei, pons, and cerebellum. Additional clinical features may include dysmorphism, abnormal eye movements, stridor, congenital joint contractures, and enlarged kidneys. Pontocerebellar hypoplasia may be associated with posterior fossa cystic malformations, cerebral atrophy, and a demyelinating neuropathy.
Curcumin is the newest therapeutic agent for ameliorating the clinical and neuropathologic phenot... more Curcumin is the newest therapeutic agent for ameliorating the clinical and neuropathologic phenotype of a mouse model of Déjérine-Sottas disease. We undertook a 12-month dose-escalation safety trial of oral curcumin in a 15-year-old Caucasian girl with Déjérine-Sottas disease (point mutation, Ser72Leu) complicated by severe weakness, scoliosis, and respiratory impairment. The patient received 50 mg/kg/day oral curcumin for the first 4 months and 75 mg/kg/day thereafter, to complete a 12-month trial. Outcome measures included muscle strength, pulmonary function, upper/lower extremity disability, neurophysiologic studies, and health-related quality of life. After 12 months, the patient experienced no adverse events, and reported good compliance. There was little improvement in objective outcome measures. Knee flexion and foot strength increased slightly, but hand and elbow strength decreased. Pulmonary function, hand function, and measures of upper/lower extremity disability were stable or reduced. Her neurophysiologic findings were unchanged. Parent-reported quality of life improved for most domains, especially self-esteem, during the 12 months of treatment. Child-reported quality of life, assessed at the final visit, mirrored these results, with overall feelings of happiness and contentment. Further studies are required to explore the efficacy and safety of curcumin for severe demyelinating neuropathies of infancy and early childhood.
The X-linked Charcot-Marie-Tooth disease is the second most common form of inherited neuropathy a... more The X-linked Charcot-Marie-Tooth disease is the second most common form of inherited neuropathy and, unlike most other forms of this disease, may present with atypical manifestations because of central nervous system involvement. Episodic central nervous system symptoms in X-linked Charcot-Marie-Tooth disease may be triggered by illness, dehydration, physical exercise, or exposure to altitude. We describe a child with transient episodes of hemiplegia after simple hyperventilation, a presentation not previously described in pediatric Charcot-Marie-Tooth disease type X.
A 14-year-old boy presented with acute paraparesis with sensory and sphincter disturbance. Imagin... more A 14-year-old boy presented with acute paraparesis with sensory and sphincter disturbance. Imaging and neurophysiologic studies were diagnostic for transverse myelitis with acute motor axonal neuropathy. He was treated with both intravenous immunoglobulin and high-dose corticosteroids, and he made a slow and incomplete recovery. Acute motor axonal neuropathy is an unusual variant of Guillain-Barré syndrome. Concomitant transverse myelitis and acute motor axonal neuropathy were not previously reported in childhood, although there are reports of coexisting transverse myelitis and other variants of Guillain-Barré syndrome. Such dual lower motor neuron pathology may be associated with a poorer outcome, and indicates simultaneous central and peripheral immune-mediated injury. There may be a place for combined therapy with immunoglobulin and corticosteroids in patients with transverse myelitis and inflammatory neuropathy.
A young adult male with cardiofaciocutaneous syndrome developed gait deterioration in childhood, ... more A young adult male with cardiofaciocutaneous syndrome developed gait deterioration in childhood, with later evolution of distal wasting. His physical examination revealed intention tremor, distal weakness of the upper limbs with atrophy of the thenar, hypothenar, and interossei muscles, a wide-based gait, and largefiber sensory loss in all limbs. Neuroimaging revealed stable mild chronic communicating hydrocephalus. Nerve conduction studies and electromyography demonstrated a moderately severe axonal neuropathy. The present case is, to our knowledge, the first reported case of peripheral neuropathy in association with cardiofaciocutaneous syndrome. The latter is a rare disorder, with significant comorbidities, in which a peripheral neuropathy may be under-recognized as a late cause of functional deterioration.
Autoimmune myasthenia gravis is a rare condition in children. Identifying antibodies directed aga... more Autoimmune myasthenia gravis is a rare condition in children. Identifying antibodies directed against the acetylcholine receptor is helpful in making the diagnosis. However, seronegative cases do exist and need to be distinguished from congenital forms of myasthenia. There is little published experience to inform the judicious management of autoimmune myasthenia gravis in children. In this article, we report our experience in the management of 12 cases of autoimmune myasthenia gravis in children in the modern era of medical immunotherapy and thymectomy. Crown
Objectives: To identify correlates of calf cramp in children with Charcot-Marie-Tooth disease typ... more Objectives: To identify correlates of calf cramp in children with Charcot-Marie-Tooth disease type 1A (CMT1A).
Pes cavus in Charcot-Marie-Tooth disease type 1A (CMT1A) is thought to be due to muscle imbalance... more Pes cavus in Charcot-Marie-Tooth disease type 1A (CMT1A) is thought to be due to muscle imbalance of the lower leg. Botulinum toxin type A (BoNT-A) can modify foot deformity in other conditions of muscle imbalance. We tested the safety and effectiveness of BoNT-A on pes cavus progression in pediatric CMT1A. A 24-month, randomized, single-blind trial of BoNT-A was undertaken in 10 affected children (20 legs), aged 3-14 years. The treated leg received intramuscular BoNT-A injections at 6-month intervals in the tibialis posterior and peroneus longus. The control leg received no injections. Primary outcome was radiographic alignment at 24 months. Secondary outcomes were foot posture, ankle flexibility, and strength, assessed every 6 months. Radiographically, BoNT-A produced a small non-significant reduction in cavus progression. There was no effect of BoNT-A on secondary outcomes. There were no serious adverse events. At 24 months, the intramuscular BoNT-A injections proved safe and well-tolerated but did not affect the progression of pes cavus in CMT1A.
Spinal muscular atrophy (SMA) is generally associated with proximal weakness and muscle wasting. ... more Spinal muscular atrophy (SMA) is generally associated with proximal weakness and muscle wasting. An X-linked variant with calf hypertrophy has been reported. We describe a young man with SMA type 4 with prominent calf hypertrophy in whom DNA analysis showed a homozygous deletion of exons 7 and 8 in the telomeric copy of the survival motor neuron gene. Calf hypertrophy may be seen uncommonly in autosomally inherited SMA.
We studied the timing and progression of foot and ankle changes in 81 children with genetically c... more We studied the timing and progression of foot and ankle changes in 81 children with genetically confirmed Charcot-Marie-Tooth disease type 1A (CMT1A) and determined their impact on motor function and walking ability. Foot deformity, weakness, pain, cramps, and instability were a common feature of CMT1A. Foot structure evolved toward pes cavus from early childhood to adolescence, although a subgroup with normal and planus feet remained. Foot strength increased with age, although compared to age-equivalent norms it declined from 4 years. Factors associated with evolving foot deformity included muscle weakness/imbalance, restricted ankle flexibility, and joint hypermobility. Regression modeling identified dorsiflexion weakness, global foot weakness, and difficulty toe-walking as independent predictors of motor dysfunction, while pes cavus and difficulty heel-walking were predictors of poor walking ability. Foot problems are present from the earliest stages of the disease and can have a negative impact on function. Early foot and ankle intervention may prevent long-term disability and morbidity in CMT1A.
Preschool-age children with neuromuscular disorders are often excluded from clinical trials due t... more Preschool-age children with neuromuscular disorders are often excluded from clinical trials due to the lack of reliable and objective strength measures. We evaluated the reliability of measuring foot and ankle muscle strength in 60 healthy children age 2-4 years. The strength of foot inversion and eversion, ankle plantarflexion, and dorsiflexion was measured using a hand-held dynamometer. Intrarater and interrater reliability of two assessors was determined for each muscle group using intraclass correlation coefficients (ICCs), 95% confidence intervals (CIs), and standard error of measurement (SEM). For all muscle groups intrarater (ICC(2,2) = 0.85-0.94, 95% CI = 0.75-0.96, SEM = 1.5-4.7 N) and interrater (ICC(2,1) = 0.88-0.96, 95% CI = 0.81-0.98, SEM = 1.2-4.6 N) reliability was high for all children. As expected, reliability was generally highest in 3- and 4-year-old children and lowest in 2-year-old children. Hand-held dynamometry can reliably measure foot and ankle strength in very young children and may help aid in diagnosis and in characterizing disease progression in disorders affecting the foot and ankle.
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Papers by Monique Ryan