- Email: [email protected]
F41. Expanding the phenotype-genotype correlations of PNPLA2 mutations
Abstracts / Clinical Neurophysiology 129 (2018) e66–e141
Results: Twenty healthy volunteers (ten men and ten women), 19– 38 years, mean 25.9 years (SD 6.3) and two case reports with SCN lesions. The mean conduction velocities of the SCN branches were 70–78 m/s (SD 8–10 m/s), and amplitudes 3–4 lV (0.9–2.0 lV). There were no differences between the sides or genders. Conclusion: NCS of the three SCN branches was feasible in all subjects, providing reference values of this new technique. The method was useful in verifying SCN lesions in two patients. doi:10.1016/j.clinph.2018.04.201
F39. Parsonage from a power tool: An unusual presentation of neuralgic amyotrophy in a 78 year old woman after using a chainsaw—John Norbury *, Molly Krause (USA) ⇑
Presenting author.
Introduction: A 78 year old Caucasian female presented for an electrodiagnostic (EDX) evaluation for right hand weakness and atrophy. Symptoms began 3 months prior one day after she was working with a chainsaw in the backyard and experienced severe right scapular pain followed by a monophasic course of progressively worsening weakness, inability to grip things such as a pen or coffee cup, and numbness and tingling into digits 1–3. Exam showed right sided prominent atrophy of the first dorsal interosseous (FDI) and thenar eminence, 4/5 strength in shoulder abduction and elbow flexion/extension, 3/5 strength in finger flexion and abduction, a positive okay sign, diminished sensation throughout the right upper limb. She also has weakness of the serratus anterior with mild medial winging of the right scapula during anteflexion. Myelogram and computed tomography showed no significant neural compression to explain patient’s symptoms, specifically no C8 compression. Methods: The patient underwent EDX testing and a neuromuscular ultrasound. Results: Nerve conduction studies showed prolonged distal onset latency and reduced amplitude of the right median motor nerve and no response in the right ulnar motor nerve, but were otherwise normal. Needle evaluation of the right FDI muscle showed reduced insertional activity with no recruitment of motor units, and the right pronator quadratus muscle showed reduced recruitment. Neuromuscular ultrasound of the right brachial plexus showed some increased hypoechogenicity and possible increased caliber compared to the left. The right forearm musculature including the pronator quadratus and FDI demonstrated increased hyperechogenicity and atrophy consistent with chronic denervation. Patient was diagnosed with a distal predominant neuralgic amyotrophy (NA) variant. Conclusion: Neuralgic amyotrophy (NA), also known as ParsonageTurner Syndrome, exhibits a high degree of phenotypic variability with only two-thirds of patients presenting with the classic phenotype with its predilection for the superior trunk of the brachial plexus. In this case, the patient met 5/5 of the clinical criteria for NA as defined by Van Alfen and neuromuscular ultrasound was helpful in further confirming the diagnosis. NA should be considered in patients even if they do not fit the classic phenotype of predominately proximal arm weakness and ultrasound of the plexus and affected muscles can be a helpful adjunctive diagnostic tool is such cases which do not ‘‘fit the textbook.” doi:10.1016/j.clinph.2018.04.202
e81
F40. Myotonic discharges in a cohort of patients with centronuclear myopathies—Jose Darlan P. Domingues, Tatiana D. Rosa, Cristina Iwabe-Marchesi, Ingrid Faber, Carlos Roberto Martins Jr., Melina P. Martins, Alberto R. Martinez *, Luciano D. Queiroz, Beatriz Helena M. Pfeilsticker, Marcondes C. Franca, Anamarli Nucci (Brazil) ⇑
Presenting author.
Introduction: Electromyography (EMG) is a useful ancillary test in the diagnosis of neuromuscular disorders. EMG patterns may be helpful to identify specific subtypes of inherited muscle disease. There are few studies looking at the EMG profile in congenital myopathies, and centronuclear myopathy (CNM) in particular. The objective of this study is to describe clinical and EMG findings in patients with CNM from a tertiary Brazilian university hospital. Methods: We selected all patients with pathological confirmation (muscle biopsy) of CNM and regularly followed at UNICAMP (State University of Campinas), from 2016 to 2017. Individuals with Xlinked CNM were not included. For each patient, we reviewed nerve conduction studies (NCS) and EMG findings at rest and during contraction of upper and lower limbs. We looked specifically at the presence of myotonic discharges. The total score of motor function measure scale (MFM32) was employed as a clinical examination marker of disease severity. Results: Eleven patients were enrolled in this study. There were six children, seven females, mean age 18.1 years when first examined in our service; a boy with 4-years-old, was the youngest and a 54-yearold lady was the oldest. The mean/median of MFM32 total score was 65.0%.The motor and sensory NCS were normal for all nerves tested. Regarding EMG and the occurrence of abnormal spontaneous activity: the myotonic discharges, when present, predominated in distal muscles: tibialis anterior and abductor pollicis brevis, and all occurred at rest. During activation, all muscles presented short duration and polyphasic motor unit action potentials without proximal or distal preferential involvement. None of the patients had clinical myotonia (either percussion or action), but electrical myotonia was found in 6 out of the 11 patients (54%). Five women and one men had clinical phenotype similar to juvenile or classical Steinert disease (DM1). Two patients had negative genetic test for the disease, and in one of the was found a mutation in the DNM2 gene. We do highlight that two patients were followed up for decades as DM1 until properly diagnosed as CNM at our hospital. Conclusion: CNM must be included in the differential diagnosis of a patient with electrical, but not clinical myotonia. Clinical neurophysiologists must be aware of this profile to assist in the recognition of CNM. The frequency of abnormal spontaneous activity at EMG is similar to other studies. doi:10.1016/j.clinph.2018.04.203
F41. Expanding the phenotype-genotype correlations of PNPLA2 mutations—Monica Alcantara *, Valeria Muniz, Marcio Venturini (Brazil) ⇑
Presenting author.
Introduction: Neutral lipid storage disease with myopathy (NLSDM), due to diverse PNPLA2 mutations, usually presents with an asymmetrical weakness, proximal involvement of upper limbs and posterior compartment of lower limbs. NLSD-M can be associated
e82
Abstracts / Clinical Neurophysiology 129 (2018) e66–e141
with other co-morbidities, like diabetes mellitus, hyperlipidemia, and most commonly, cardiomyopathy, which can be detected in almost 50% of patients. Although clinical manifestations begin around the third decade, late onset disease with unusual symptoms, such as fatigue and exercise intolerance, has been reported. Magnetic resonance imaging (MRI) of skeletal muscles reveals fatty degeneration, with a predilection for shoulder girdle and lower limb muscles. Electromyographic (EMG) features have been reported in one patient, where complex repetitive discharges (CRD) and myotonic discharges were detected in a few muscles. Methods: Description of the clinical, neurophysiological, muscle MRI, pathological and genetic findings of a novel mutation in the PNPLA2 gene. This work received ethics board approval. Results: Two sisters (aged 31 years at first examination), born 3 years apart from consanguineous parents, presented with a 2 year history of progressive motor deficits, proximal/asymmetric in upper limbs and distal/symmetric in lower limbs. The most severely affected muscles were: deltoids, biceps, external cuff rotators, gastrocnemius and tibialis anterior muscles. EMG recordings showed diffuse short-duration motor unit potentials, with asymmetrical distribution; some long duration, polyphasic potentials in distal muscles; profuse CRD in the biceps and tibialis anterior and sparse CRD in paravertebral muscles. MRI revealed an asymmetrical fatty replacement in the posterior compartment of thigs and legs, paravertebral musculature, deltoids and biceps. Jordans’ anomaly, characterized by lipid accumulation in leukocytes, was detected in peripheral blood smears in both patients. Muscle biopsy showed cytoplasmic vacuoles, suggestive of neutral lipid accumulation. Genetic analysis revealed a homozygous deletion in exon 6 of PNPLA2 gene (c.995delG), not yet described in the literature. Five years after the initial symptoms, the elder sister was completely dependent for upper limb activities, although she had independent walking, while the younger sister had only minor fine motor skills impairment. Creatine phosphokinase levels increased in a stepwise manner over the years in the elder sister (97–2840 UI/L), while stable levels were found in the younger one (621–681 UI/L). Cardiomyopathy was not present in those patients. Conclusion: NLSD-M due to PNPLA2 gene mutations should be suspected in patients presenting with an asymmetrical myopathy with upper limb predominance; profuse and also asymmetrical EMG and MRI abnormalities, even without cardiomyopathy. Although some mutations have been described, genotypical variability seems to be common, so novel mutations should be sought for genetic counselling purposes. doi:10.1016/j.clinph.2018.04.204
F42. EMG findings in patients with limb-girdle muscular dystrophy due to heterozygous CAPN3 mutations—Antonio Rodrigues Coimbra Neto, Tauana B. Leoni, Fabricio Diniz de Lima, Alberto Rolim Muro Martinez, Anamarli Nucci, Marcondes Cavalcante França Jr. * (Brazil) ⇑
Presenting author.
Introduction: Limb-girdle muscular dystrophy type 2A (LGMD2A) is the most common autosomal recessive (AR) LGMD subtype worldwide. The disease is caused by homozygous pathogenic mutations in the calpain 3 gene (CAPN3). Although strict AR inheritance is assumed for CAPN3-related myopathies, recent reports described symptomatic patients carrying a single CAPN3 mutation. The LGMDs share common clinical and laboratory findings such as weakness and atrophy of proximal muscles, often affecting lower extremities first; elevated creatine kinase (CK) levels; and dystrophic
findings on muscle biopsy. Some clinical and imaging findings help to differentiate LGMD2A, such as asymmetric weakness and atrophy and early scapular winging. On muscle MRI, calpain deficiency characteristically reveals preferential involvement of posterior thigh muscles and the adductor magnus muscle with relative sparing of the anterior thigh muscles. There are few reports on EMG findings in patients with single CAPN3 mutations. Methods: Two unrelated patients with LGMD and harboring single CAPN3 mutations were identified. They underwent detailed neurological evaluation, muscle biopsy, muscle MRI and electroneuromyography (ENMG). Results: Patient one: man, 28 years old, born from nonconsanguineous parents, presenting progressive calves atrophy since 24 years old. Genetic analysis showed the variant c.258dupT;p. (Leu87Serfs*4) at CAPN3 in heterozygosity. ENMG showed myopathic motor unit action potential (MUAP) on left gastrocnemius and pectoralis major, and on right biceps brachii, without fibs or positive sharp waves. Right gastrocnemius muscle biopsy showed moderate myopathic changes. Patient two: woman, 77 years old, born from nonconsanguineous parents, presenting progressive proximal lower limb weakness in the last 2 years. Genetic analysis revealed the heterozygous frameshift variant c.550delA; p. (Thr184Argfs*36) in the CAPN3 gene. ENMG showed moderate diffuse myopathy, with preferential involvement of posterior tigh muscles and gastrocnemius with fibs and positive sharp waves. MRI showed severe atrophy of posterior tight muscles. Right quadriceps femoris biopsy revealed minimal myopathic changes. Conclusion: The typical clinical, imaging and electrophysiological findings from LGMD2A can be found in patients presenting heterozygous pathogenic mutations in CAPN3 gene, indicating that a dominantly inherited form of calpainopathy exists, but with a milder fenotype. EMG reveals a predominantly posterior leg pattern of involvement. doi:10.1016/j.clinph.2018.04.205
F43. Electrophysiological tests in patients with anti-MuSK myasthenia gravis: A retrospective study—Anna De Rosa *, Roberta Ricciardi, Tommaso Bocci, Michelangelo Maestri, Melania Guida, Ubaldo Bonuccelli (Italy) ⇑
Presenting author.
Introduction: Myasthenia gravis (MG) with autoantibodies to muscle-specific tyrosine kinase (MuSK) represents a distinct type of disease, as compared MG with antibodies against acetylcholine receptor (AchR-Abs). MuSK-MG patients have peculiar clinical features characterized by predominant oculo-bulbar symptoms and a lack of response to conventional MG treatments. Since the role of electrophysiological tests in MuSK patients is still argued, our aim was to investigate their electrophysiological profile in order to arise a light over this darkness. Methods: We retrospectively evaluated repetitive nerve stimulation (RNS) and single-fibre electromyography (SF-EMG) reports of 63 MuSK patients, at the time of MG diagnosis, and we compared them with 35 non-timomatous AChR-Abs positive patients matched with MuSK group according to gender, age at onset of MG, age at MG diagnosis and severity of the disease. Disease severity was graded according to Myasthenia Gravis Foundation of America (MGFA) classification. Seronegative patients and thymoma-associated MG patients were excluded from the study. Results: Sixty-three MuSK patients (11 males; 52 females; mean age at MG onset: 37 ± 2.0; mean age at diagnosis: 38.7 ± 2.0) and 35 AChR-Abs positive patients (9 males; 26 females; mean age at
Results: Twenty healthy volunteers (ten men and ten women), 19– 38 years, mean 25.9 years (SD 6.3) and two case reports with SCN lesions. The mean conduction velocities of the SCN branches were 70–78 m/s (SD 8–10 m/s), and amplitudes 3–4 lV (0.9–2.0 lV). There were no differences between the sides or genders. Conclusion: NCS of the three SCN branches was feasible in all subjects, providing reference values of this new technique. The method was useful in verifying SCN lesions in two patients. doi:10.1016/j.clinph.2018.04.201
F39. Parsonage from a power tool: An unusual presentation of neuralgic amyotrophy in a 78 year old woman after using a chainsaw—John Norbury *, Molly Krause (USA) ⇑
Presenting author.
Introduction: A 78 year old Caucasian female presented for an electrodiagnostic (EDX) evaluation for right hand weakness and atrophy. Symptoms began 3 months prior one day after she was working with a chainsaw in the backyard and experienced severe right scapular pain followed by a monophasic course of progressively worsening weakness, inability to grip things such as a pen or coffee cup, and numbness and tingling into digits 1–3. Exam showed right sided prominent atrophy of the first dorsal interosseous (FDI) and thenar eminence, 4/5 strength in shoulder abduction and elbow flexion/extension, 3/5 strength in finger flexion and abduction, a positive okay sign, diminished sensation throughout the right upper limb. She also has weakness of the serratus anterior with mild medial winging of the right scapula during anteflexion. Myelogram and computed tomography showed no significant neural compression to explain patient’s symptoms, specifically no C8 compression. Methods: The patient underwent EDX testing and a neuromuscular ultrasound. Results: Nerve conduction studies showed prolonged distal onset latency and reduced amplitude of the right median motor nerve and no response in the right ulnar motor nerve, but were otherwise normal. Needle evaluation of the right FDI muscle showed reduced insertional activity with no recruitment of motor units, and the right pronator quadratus muscle showed reduced recruitment. Neuromuscular ultrasound of the right brachial plexus showed some increased hypoechogenicity and possible increased caliber compared to the left. The right forearm musculature including the pronator quadratus and FDI demonstrated increased hyperechogenicity and atrophy consistent with chronic denervation. Patient was diagnosed with a distal predominant neuralgic amyotrophy (NA) variant. Conclusion: Neuralgic amyotrophy (NA), also known as ParsonageTurner Syndrome, exhibits a high degree of phenotypic variability with only two-thirds of patients presenting with the classic phenotype with its predilection for the superior trunk of the brachial plexus. In this case, the patient met 5/5 of the clinical criteria for NA as defined by Van Alfen and neuromuscular ultrasound was helpful in further confirming the diagnosis. NA should be considered in patients even if they do not fit the classic phenotype of predominately proximal arm weakness and ultrasound of the plexus and affected muscles can be a helpful adjunctive diagnostic tool is such cases which do not ‘‘fit the textbook.” doi:10.1016/j.clinph.2018.04.202
e81
F40. Myotonic discharges in a cohort of patients with centronuclear myopathies—Jose Darlan P. Domingues, Tatiana D. Rosa, Cristina Iwabe-Marchesi, Ingrid Faber, Carlos Roberto Martins Jr., Melina P. Martins, Alberto R. Martinez *, Luciano D. Queiroz, Beatriz Helena M. Pfeilsticker, Marcondes C. Franca, Anamarli Nucci (Brazil) ⇑
Presenting author.
Introduction: Electromyography (EMG) is a useful ancillary test in the diagnosis of neuromuscular disorders. EMG patterns may be helpful to identify specific subtypes of inherited muscle disease. There are few studies looking at the EMG profile in congenital myopathies, and centronuclear myopathy (CNM) in particular. The objective of this study is to describe clinical and EMG findings in patients with CNM from a tertiary Brazilian university hospital. Methods: We selected all patients with pathological confirmation (muscle biopsy) of CNM and regularly followed at UNICAMP (State University of Campinas), from 2016 to 2017. Individuals with Xlinked CNM were not included. For each patient, we reviewed nerve conduction studies (NCS) and EMG findings at rest and during contraction of upper and lower limbs. We looked specifically at the presence of myotonic discharges. The total score of motor function measure scale (MFM32) was employed as a clinical examination marker of disease severity. Results: Eleven patients were enrolled in this study. There were six children, seven females, mean age 18.1 years when first examined in our service; a boy with 4-years-old, was the youngest and a 54-yearold lady was the oldest. The mean/median of MFM32 total score was 65.0%.The motor and sensory NCS were normal for all nerves tested. Regarding EMG and the occurrence of abnormal spontaneous activity: the myotonic discharges, when present, predominated in distal muscles: tibialis anterior and abductor pollicis brevis, and all occurred at rest. During activation, all muscles presented short duration and polyphasic motor unit action potentials without proximal or distal preferential involvement. None of the patients had clinical myotonia (either percussion or action), but electrical myotonia was found in 6 out of the 11 patients (54%). Five women and one men had clinical phenotype similar to juvenile or classical Steinert disease (DM1). Two patients had negative genetic test for the disease, and in one of the was found a mutation in the DNM2 gene. We do highlight that two patients were followed up for decades as DM1 until properly diagnosed as CNM at our hospital. Conclusion: CNM must be included in the differential diagnosis of a patient with electrical, but not clinical myotonia. Clinical neurophysiologists must be aware of this profile to assist in the recognition of CNM. The frequency of abnormal spontaneous activity at EMG is similar to other studies. doi:10.1016/j.clinph.2018.04.203
F41. Expanding the phenotype-genotype correlations of PNPLA2 mutations—Monica Alcantara *, Valeria Muniz, Marcio Venturini (Brazil) ⇑
Presenting author.
Introduction: Neutral lipid storage disease with myopathy (NLSDM), due to diverse PNPLA2 mutations, usually presents with an asymmetrical weakness, proximal involvement of upper limbs and posterior compartment of lower limbs. NLSD-M can be associated
e82
Abstracts / Clinical Neurophysiology 129 (2018) e66–e141
with other co-morbidities, like diabetes mellitus, hyperlipidemia, and most commonly, cardiomyopathy, which can be detected in almost 50% of patients. Although clinical manifestations begin around the third decade, late onset disease with unusual symptoms, such as fatigue and exercise intolerance, has been reported. Magnetic resonance imaging (MRI) of skeletal muscles reveals fatty degeneration, with a predilection for shoulder girdle and lower limb muscles. Electromyographic (EMG) features have been reported in one patient, where complex repetitive discharges (CRD) and myotonic discharges were detected in a few muscles. Methods: Description of the clinical, neurophysiological, muscle MRI, pathological and genetic findings of a novel mutation in the PNPLA2 gene. This work received ethics board approval. Results: Two sisters (aged 31 years at first examination), born 3 years apart from consanguineous parents, presented with a 2 year history of progressive motor deficits, proximal/asymmetric in upper limbs and distal/symmetric in lower limbs. The most severely affected muscles were: deltoids, biceps, external cuff rotators, gastrocnemius and tibialis anterior muscles. EMG recordings showed diffuse short-duration motor unit potentials, with asymmetrical distribution; some long duration, polyphasic potentials in distal muscles; profuse CRD in the biceps and tibialis anterior and sparse CRD in paravertebral muscles. MRI revealed an asymmetrical fatty replacement in the posterior compartment of thigs and legs, paravertebral musculature, deltoids and biceps. Jordans’ anomaly, characterized by lipid accumulation in leukocytes, was detected in peripheral blood smears in both patients. Muscle biopsy showed cytoplasmic vacuoles, suggestive of neutral lipid accumulation. Genetic analysis revealed a homozygous deletion in exon 6 of PNPLA2 gene (c.995delG), not yet described in the literature. Five years after the initial symptoms, the elder sister was completely dependent for upper limb activities, although she had independent walking, while the younger sister had only minor fine motor skills impairment. Creatine phosphokinase levels increased in a stepwise manner over the years in the elder sister (97–2840 UI/L), while stable levels were found in the younger one (621–681 UI/L). Cardiomyopathy was not present in those patients. Conclusion: NLSD-M due to PNPLA2 gene mutations should be suspected in patients presenting with an asymmetrical myopathy with upper limb predominance; profuse and also asymmetrical EMG and MRI abnormalities, even without cardiomyopathy. Although some mutations have been described, genotypical variability seems to be common, so novel mutations should be sought for genetic counselling purposes. doi:10.1016/j.clinph.2018.04.204
F42. EMG findings in patients with limb-girdle muscular dystrophy due to heterozygous CAPN3 mutations—Antonio Rodrigues Coimbra Neto, Tauana B. Leoni, Fabricio Diniz de Lima, Alberto Rolim Muro Martinez, Anamarli Nucci, Marcondes Cavalcante França Jr. * (Brazil) ⇑
Presenting author.
Introduction: Limb-girdle muscular dystrophy type 2A (LGMD2A) is the most common autosomal recessive (AR) LGMD subtype worldwide. The disease is caused by homozygous pathogenic mutations in the calpain 3 gene (CAPN3). Although strict AR inheritance is assumed for CAPN3-related myopathies, recent reports described symptomatic patients carrying a single CAPN3 mutation. The LGMDs share common clinical and laboratory findings such as weakness and atrophy of proximal muscles, often affecting lower extremities first; elevated creatine kinase (CK) levels; and dystrophic
findings on muscle biopsy. Some clinical and imaging findings help to differentiate LGMD2A, such as asymmetric weakness and atrophy and early scapular winging. On muscle MRI, calpain deficiency characteristically reveals preferential involvement of posterior thigh muscles and the adductor magnus muscle with relative sparing of the anterior thigh muscles. There are few reports on EMG findings in patients with single CAPN3 mutations. Methods: Two unrelated patients with LGMD and harboring single CAPN3 mutations were identified. They underwent detailed neurological evaluation, muscle biopsy, muscle MRI and electroneuromyography (ENMG). Results: Patient one: man, 28 years old, born from nonconsanguineous parents, presenting progressive calves atrophy since 24 years old. Genetic analysis showed the variant c.258dupT;p. (Leu87Serfs*4) at CAPN3 in heterozygosity. ENMG showed myopathic motor unit action potential (MUAP) on left gastrocnemius and pectoralis major, and on right biceps brachii, without fibs or positive sharp waves. Right gastrocnemius muscle biopsy showed moderate myopathic changes. Patient two: woman, 77 years old, born from nonconsanguineous parents, presenting progressive proximal lower limb weakness in the last 2 years. Genetic analysis revealed the heterozygous frameshift variant c.550delA; p. (Thr184Argfs*36) in the CAPN3 gene. ENMG showed moderate diffuse myopathy, with preferential involvement of posterior tigh muscles and gastrocnemius with fibs and positive sharp waves. MRI showed severe atrophy of posterior tight muscles. Right quadriceps femoris biopsy revealed minimal myopathic changes. Conclusion: The typical clinical, imaging and electrophysiological findings from LGMD2A can be found in patients presenting heterozygous pathogenic mutations in CAPN3 gene, indicating that a dominantly inherited form of calpainopathy exists, but with a milder fenotype. EMG reveals a predominantly posterior leg pattern of involvement. doi:10.1016/j.clinph.2018.04.205
F43. Electrophysiological tests in patients with anti-MuSK myasthenia gravis: A retrospective study—Anna De Rosa *, Roberta Ricciardi, Tommaso Bocci, Michelangelo Maestri, Melania Guida, Ubaldo Bonuccelli (Italy) ⇑
Presenting author.
Introduction: Myasthenia gravis (MG) with autoantibodies to muscle-specific tyrosine kinase (MuSK) represents a distinct type of disease, as compared MG with antibodies against acetylcholine receptor (AchR-Abs). MuSK-MG patients have peculiar clinical features characterized by predominant oculo-bulbar symptoms and a lack of response to conventional MG treatments. Since the role of electrophysiological tests in MuSK patients is still argued, our aim was to investigate their electrophysiological profile in order to arise a light over this darkness. Methods: We retrospectively evaluated repetitive nerve stimulation (RNS) and single-fibre electromyography (SF-EMG) reports of 63 MuSK patients, at the time of MG diagnosis, and we compared them with 35 non-timomatous AChR-Abs positive patients matched with MuSK group according to gender, age at onset of MG, age at MG diagnosis and severity of the disease. Disease severity was graded according to Myasthenia Gravis Foundation of America (MGFA) classification. Seronegative patients and thymoma-associated MG patients were excluded from the study. Results: Sixty-three MuSK patients (11 males; 52 females; mean age at MG onset: 37 ± 2.0; mean age at diagnosis: 38.7 ± 2.0) and 35 AChR-Abs positive patients (9 males; 26 females; mean age at