Atrofia muscular espinal y bulbar: enfermedad de Kennedy. Aspectos clínicos y genéticos / Spinal and bulbar muscular atrophy (SBMA): Kennedy's disease. Clinical and genetic aspects

La atrofia muscular espinal y bulbar es una enfermedad neurológica caracterizada por degeneración gradual de la motoneurona inferior, que resulta en debilidad muscular, atrofia y fasciculaciones. Es una entidad de etiología genética con mecanismo de herencia ligado al cromosoma X recesivo, por lo que afecta a varones, en la que se produce una expansión del triplete CAGn en el gen del receptor de andrógenos. Se manifiesta por signos de insensibilidad a los andrógenos (ginecomastia e infertilidad). A partir de los 20-30 años, aproximadamente, comienzan los signos de afectación de la motoneurona inferior a nivel espinal con calambres y temblor de acción y posteriormente debilidad muscular. En la evolución se evidencia compromiso bulbar. Se presenta el caso clínico-genealógico de un varón de 32 años con temblores en quien se confirma molecularmente la enfermedad de Kennedy. Este es el primer caso, hasta nuestro conocimiento, reportado en Uruguay. Se destaca la importancia de plantear dicha afección en un paciente joven con "temblores" cuando aún no es ostensible la debilidad muscular. La historia familiar es de capital importancia. La presencia de fasciculaciones en el estudio eléctrico a nivel perioral es muy sugestiva de esta patología. La confirmación molecular es importante para el asesoramiento genético.

Spinal and bulbar muscular atrophy (SBMA) is a neurological disease characterized by the progressive degeneration of the inferior motor neurones, what results in muscle weakness, atrophy and fasciculations. It possesses a genetic etiology with X-linked recessive inheritance mode, and thus affects men. There is an abnormal expansion of the CAG polyglutamine encoding repeat within the androgen receptor gene. It is noticed by signs of androgen insentistivity (gynecomastia and infertility). At 20-30 years old approximately signs of compromise of the lower motor neurones in the spine are seen in cramps and action tremor followed by muscle weakness, evidencing bulbar involvement in the evolution. The study presents the ciínical-genealogical case of a 32 year-old male with tremor, whose Kennedy disease was confirmed with molecules. This is the first case reported in Uruguay as far as we know. The importance of considering this condition is pointed out in a young patient with "tremor" when muscle weakness is not evident yet. Family history is key. The presence of fasciculation in the electrical study strongly suggests this condition. Molecular confirmation is important for genetic advice purposes.

A atrofia muscular bulbo-espinal (BSMA) é uma doença neurológica caracterizada pela degeneração gradual do neurônio motor inferior causando fraqueza muscular, atrofia e fasciculações. É uma entidade de etiologia genética com mecanismo de herança ligada ao cromossoma X recessivo, afetando por isso a indivíduos do sexo masculino, nos quais se observa a expansão do triplete CAGn no gene do Receptor de Andrógenos (RA). Manifesta-se pela ausência de sensibilidade aos andrógenos (ginecomastia e infertilidade); a partir dos 20-30 anos aproximadamente começam a manifestar-se os sinais de afetação do neurônio motor inferior na região espinal com câimbras e tremor de ação e posteriormente debilidade muscular. Em sua evolução observa-se compromisso bulbar. Apresenta-se o caso clínico - genealógico de um indivíduo de sexo masculino de 32 anos com tremores, no qual foi realizado diagnóstico molecular de doença de Kennedy. Este é o primeiro caso informado no Uruguai, que seja de nosso conhecimento. Destaca-se a importância da suspeita desta afecção em um paciente jovem com "tremores" mesmo quando a debilidade muscular ainda não é ostensível. A história familiar é fundamental. A presença de fasciculações no estudo elétrico na região perioral é muito sugestiva desta patologia. A confirmação molecular é importante para o assessoramento genético.

X-linked spinal and bulbar muscular atrophy (Kennedy's disease): the first case described in the Brazilian Amazon / Atrofia muscular bulboespinhal ligada ao cromossomo X (doença de Kennedy): o primeiro caso descrito na Amazônia brasileira

ABSTRACT The X-linked spinal and bulbar muscular atrophy (Kennedy's disease) is a rare X-linked, recessive, lower motor neuron disease, characterized by weakness, atrophy, and fasciculations of the appendicular and bulbar muscle. The disease is caused by an expansion of the CAG repetition in the androgen receptor gene. Patients with Kennedy's disease have more than 39 CAG repetitions. We report a case of 57-year-old man, resident of Monte Dourado (PA, Brazil) who complained of brachiocrural paresis evolving for 3 years along with fasciculations and tremors of extremities. In addition, he also developed dysarthria, dysphagia, and sexual dysfunction. The patient clinical picture included gait impairment, global hyporeflexia, proximal muscle atrophy of upper limbs, deviation of the uvula to right during phonation and tongue atrophy with fasciculations. The patient reported that about 30 years ago he had undergone gynecomastia surgery. His electroneuromyography suggested spinal muscular atrophy, and nuclear magnetic resonance imaging showed tapering of the cervical and thoracic spinal cord. Patient's creatine kinase level was elevated. In view of the findings, an exam was requested to investigate Kennedy's disease. The exam identified 46 CAG repetitions in the androgen receptor gene, which confirmed the diagnostic suspicion. This was the first case of Kennedy's disease diagnosed and described in the Brazilian Amazon. To our knowledge only other four papers were published on this disease in Brazilian patients. A brief review is also provided on etiopathogenic, clinical and diagnostic aspects.

RESUMO A atrofia muscular bulboespinhal ligada ao cromossomo X (doença de Kennedy) é uma rara doença de neurônio motor inferior, recessiva, ligada ao X, e caracterizada por fraqueza, atrofia e fasciculações da musculatura apendicular e bulbar. É causada por uma expansão da repetição CAG no gene do receptor de androgênio. Pacientes com doença de Kennedy apresentam mais de 39 repetições CAG. O paciente deste relato era do sexo masculino, 57 anos, morador de Monte Dourado (PA, Brasil), com queixa de paresia braquiocrural há 3 anos, acompanhada de fasciculações e tremores de extremidades. Em seguida, ele desenvolveu disartria, disfagia e disfunção sexual. Também apresentava comprometimento da marcha, hiporreflexia global, atrofia muscular proximal dos membros superiores, desvio da úvula para direita à fonação e atrofia de língua com fasciculações. Foi realizada cirurgia para tratamento de ginecomastia há 30 anos. A eletroneuromiografia sugeriu quadro de atrofia muscular espinhal. Imagens de ressonância magnética demonstraram afilamento da medula espinhal cervical e torácica. A creatina quinase estava elevada. Diante dos achados, solicitou-se investigação para doença de Kennedy, e foram identificadas 46 repetições CAG no gene do receptor de androgênio, o que confirmou a suspeita diagnóstica. Este foi o primeiro caso de doença de Kennedy diagnosticado e descrito na Amazônia brasileira. Existem, além deste relato, apenas outros quatro trabalhos publicados sobre a doença em pacientes do Brasil. Também realizamos breve revisão de aspectos etiopatogênicos, clínicos e diagnósticos.

Avaliação da funcionalidade de indivíduos de uma mesma família com doença de Kennedy / Functionality evaluation of subjects of the same family with Kennedy's Disease

OBJETIVOS: Avaliar a funcionalidade de indivíduos de uma mesma família que apresentam a Doença de Kennedy e compará-la com o resultado obtido após um ano e meio, para verificar a evolução da doença. MÉTODOS: Série de casos, em que foram avaliados, em dois momentos separados por um ano e meio, seis indivíduos de uma mesma família com Doença de Kennedy. O instrumento de aferição utilizado foi o Core Set da Classificação Internacional de Funcionalidade, Incapacidade e Saúde para doenças neuromusculares. Esse questionário estruturado busca informações sobre domínios da saúde, situações da funcionalidade e suas restrições. Os dados foram analisados no SPSS versão 20.0, com análise descritiva. RESULTADOS: Após um ano e meio, houve piora nos componentes função do corpo, com consequente declínio da função, demonstrado no componente atividade e participação. Apenas um domínio do componente "função corporal" apresentou melhora na segunda avaliação. Durante o período avaliado, a maioria dos fatores ambientais facilitadores (barras ou corrimão em escadas, barras internas nas residências, rampas, plano de saúde, dispositivos auxiliares de marcha, automóvel, telefone e portão eletrônico) mantiveram-se presentes, mas aumentou a magnitude de deficiência de alguns produtos e tecnologias de apoio (escadas e banheiro sem barras), o que pode ter prejudicado a funcionalidade desses indivíduos. CONCLUSÕES: A funcionalidade mostrou-se alterada em indivíduos com Doença de Kennedy, e a evolução da doença acentuou a deficiência nos componentes da Classificação Internacional de Funcionalidade após um ano e meio. Houve falta de alguns produtos e tecnologias de apoio para uso pessoal na vida diária.

AIMS: To assess the functionality of individuals of a same family who present Kennedy's disease, and to compare it with the results obtained after one year and a half to verify the evolution of the disease. METHODS: Case series, in which six individuals with Kennedy's disease were evaluated in two moments separated by one year and a half. The instrument used was the Core Set for International Classification of Functioning, Disability and Health for neuromuscular diseases. This structured questionnaire seeks information on health domains, functional situations and their restrictions. The data were analyzed in SPSS version 20.0, with descriptive analysis. RESULTS: After one year and a half the body function components worsened, with consequent decline in function, demonstrated in the activity and participation component. Only one domain of the body function component had improvement in the second evaluation. During the evaluation period, several facilitating environmental factors (bars or stair rails, internal bars in residences, ramps, health plan, gaiters, automobile, telephone and electronic gate) remained. However, the magnitude of the deficiency of some products and supporting technologies (stairs and bathroom without bars) increased, which may have impaired the functionality of these individuals. CONCLUSIONS: Functionality was altered in individuals with Kennedy's disease, and the disease progression has accentuated the deficiency in the components of the International Classification of Functionality after one year and a half. There was a lack of some supporting products and technologies to personal use in daily life.

Clinical features of a genetically identified spinal and bulbar muscular atrophy pedigree / 中南大学学报(医学版)

Spinal and bulbar muscular atrophy (SBMA) is a rare X-linked motor neuron disease with significant phenotypic viability. Here, we present a genetically identified SBMA family without bulbar paralysis or androgen insensitivity. All four male patients presented with progressive lower motor neuron paralysis in all limbs, with distal extremities more dominant. None of them had bulbar palsy or androgen insensitivity. A consistently mild elevated blood creatine phosphokinase (CPK) levels were detected in all patients and the EMG showed a chronic neurogenic damage. Muscle biopsy of propositus indicated a typical neurogenic amyotrophy. Genetic testing for SMA of mutation in SMN1 was negative, while for SBMA of androgen receptor showed the increased CAG repeat in exon 1, suggesting that although bulbar symptoms and androgen insensitivity are characteristic symptoms of SBMA, they are not obligatory for the diagnosis. In adult males with a chronic motor neuron syndrome without upper motor neuron signs, even in absence of the classical features of androgen insensitivity or bulbar findings, genetic testing for SBMA should be strongly considered.

Clinical Characteristics and Genotype-Phenotype Correlation of Korean Patients with Spinal and Bulbar Muscular Atrophy

PURPOSE: Spinal and bulbar muscular atrophy (SBMA) is an X-linked motor neuron disease characterized by proximal muscle weakness, muscle atrophy, and fasciculation. Although SBMA is not uncommon in Korea, there is only one study reporting clinical characteristics and genotype-phenotype correlation in Korean patients. MATERIALS AND METHODS: In this study, age at the onset of symptoms, the score of severity assessed by impairment of activities of daily living milestones, and rate of disease progression, and their correlations with the number of CAG repeats in the androgen receptor (AR) gene, as well as possible correlations among clinical characteristics, were analyzed in 40 SBMA patients. RESULTS: The median ages at onset and at diagnosis were 44.5 and 52.5 years, respectively, and median interval between onset and diagnosis and median rate of disease progression were 5.0 years and 0.23 score/year, respectively. The median number of CAG repeats in the AR gene was 44 and the number of CAG repeats showed a significant inverse correlation with the age at onset of symptoms (r=-0.407, p=0.009). In addition, patients with early symptom onset had slower rate of disease progression. CONCLUSION: As a report with the largest and recent Korean cohort, this study demonstrates clinical features of Korean patients with SBMA and reaffirms the inverse correlation between the age at disease onset and the number of CAG repeats. Interestingly, this study shows a possibility that the rate of disease progression may be influenced by the age at onset of symptoms.

Kennedy Disease: 3-year Experience of Home Parenteral and Enteral Nutrition

A 69-year-old man was consulted to our Home Health Care department for home parenteral enteral nutrition. He was diagnosed with Kennedy disease. He had swallowing difficulty and bowel ischemia. We provided nutritional support in a variety of ways in order to suit his condition. The role of the home care nurse involves training methods depending on changes in the nutritional support to patient and care giver. However, in the case of Kennedy disease, increasing the target patient's nutritional requirements as calculated was difficult.

Comparison of clinical and physiological characteristics between Kennedy disease and amyotrophic lateral sclerosis / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the clinical presentations of Kennedy disease (KD) and compare the neurophysiological features between KD and amyotrophic lateral sclerosis(ALS).</p><p><b>METHODS</b>Nine patients with KD, 13 patients with ALS and 26 normal control subjects were recruited. The clinical presentations of KD were analyzed, and the results of nerve conduction studies and electromyography were compared among the 3 groups.</p><p><b>RESULTS</b>The rates of tongue atrophy and facial fasciculation were 100% and 88.9%, respectively, in the early course and mid-course of KD, sensory damages might be perceived. 2)The sural nerve sensory nerve action potential (SNAP) was not elicited in 56.3% of the patients with KD, and sural nerve SNAP amplitudes were significantly lower in KD (7.9. ± 3.4 µV) than in ALS patients (20.0 ± 5.2 µV) and normal control subjects (26.1 ± 16.8 µV) (P<0.05).</p><p><b>CONCLUSION</b>B The onset of clinical presentations mimicking motor neuron disease, appearance of tongue atrophy and facial fasciculation in the early and mid-course, and presence of sensory impairment with a decreased sural nerve SNAP amplitude may suggest the diagnosis of KD and should prompt a genetic test for KD.</p>

Investigation of a family with Kennedy disease by genetic analysis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To report on a Chinese family from Wenzhou with genetically confirmed Kennedy disease and describe its clinical and genetic features.</p><p><b>METHODS</b>The clinical phenotype and the level of relevant biochemical markers were assessed. To determine the number of CAG repeats in the exon 1 of androgen receptor (AR) gene, genomic DNA was extracted from peripheral blood samples of the family members, amplified by PCR and identified by DNA sequencing.</p><p><b>RESULTS</b>The proband showed predominantly proximal limb weakness, fasciculation, muscle atrophy, gynecomastia, sexual dysfunction and increased serum creatine kinase. Myopathy and neuropathy were identified by electromyography. Two other affected males and 2 affected female carriers were identified to carry an expanded CAG repeat in the AR gene. The numbers of CAG repeats were found to be 43 in the proband, 43 and 42 in the other two affected males, one of which had similar clinical symptoms to the proband.</p><p><b>CONCLUSION</b>The family was diagnosed with Kennedy disease by analysis of the AR gene.</p>

Molecular diagnosis for a patient with Kennedy disease / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To screen for potential mutations of androgen receptor (AR) gene in a patient clinically diagnosed as Kennedy disease.</p><p><b>METHODS</b>Polyglutamine expansion (PQE) induced by a duplication of CAG trinucleotide tandem-repeat in exon 1 of the AR gene was detected with PCR and T-clone sequencing.</p><p><b>RESULTS</b>Compared with the number of CAG repeat of 22 in the normal allele, the number of CAG repeats has increased to 45 in the mutant allele carried by the patient. This has fit with the diagnostic criteria for Kennedy disease.</p><p><b>CONCLUSION</b>A mutation of PQE has been detected in the patient with Kennedy disease. Detection of PQE in AR gene can be used as reliable method to identify the Kennedy disease.</p>

Enfermedad de Kennedy en el Perú: Primeros casos con diagnóstico molecular / Kennedy disease in Peru: First cases with molecular diagnosis

La enfermedad de Kennedy es un trastorno neurodegenerativo de herencia recesiva ligada al cromosoma X, de inicio en la adultez, caracterizado por degeneración progresiva de las neuronas motoras espinales, debido a una mutación dinámica del gen del receptor de andrógeno. Se presentan tres familias (cinco casos) con temblor, calambres, debilidad muscular generalizada lentamente progresiva con atrofia, afectación de músculos bulbares y alteraciones endocrinas. El estudio neurofisiológico demostró compromiso de segunda motoneurona. El análisis molecular mostró una expansión anormal de tripletes citosina-adenina-guanina en el gen de receptor de andrógeno en todos los casos. Todos los pacientes cursaron con una presentación clínica típica de la enfermedad siendo los primeros casos de enfermedad de Kennedy con diagnóstico molecular realizado en el Perú.

Kennedy’s disease is an X-linked recessive disorder with onset in adulthood, characterized by progressive degeneration of spinal motor neurons due to a dynamic mutation in the androgen receptor gene. We report three families (five cases) characterized by progressive weakness involving both limbs and bulbar muscles, atrophy, tremor, cramps and endocrinologic disturbances; the neurophysiological studies demonstrated second motor neuron impairment. The molecular analysis identified abnormal CAG repeats expansion in the androgen receptor gene (AR) in all cases. Clinical features were consistent with other previous reports. These are the first Peruvian cases of Kennedy´s disease with confirmed molecular diagnosis.

Decremental Responses to Repetitive Nerve Stimulation in X-Linked Bulbospinal Muscular Atrophy

BACKGROUND AND PURPOSE: X-linked bulbospinal muscular atrophy (X-BSMA) is characterized by bulbar and spinal muscular weakness and fasciculations. Although X-BSMA is a motor neuronopathy, there are several reports of myasthenic symptoms or decremental responses to repetitive nerve stimulation (RNS). We report the results of applying the RNS test to 15 patients among 41 with genetically confirmed X-BSMA; these 15 patients complained of fatigue, ease of becoming tired, or early muscular exhaustion. METHODS: The 3-Hz RNS test was performed on the trapezius, nasalis, orbicularis oculi, flexor carpi ulnaris, and abductor digiti quinti muscles. A decrement greater than 10% was considered abnormal. Additionally, a pharmacologic response to neostigmine was identified in three patients. RESULTS: A significant decrement was observed in 67% of patients, and was most common in the trapezius muscle (nine cases). The decrement of the trapezius muscle response ranged from 15.9% to 36.9%. The decrement was inversely correlated with the amplitude of compound muscle action potentials at rest. Neostigmine injection markedly improved the decrement in three patients, who showed noticeable decremental responses to 3-Hz RNS. CONCLUSIONS: This study shows that myasthenic symptoms and abnormal decremental responses to low-rate RNS are common in X-BSMA.

Tremor in X-linked recessive spinal and bulbar muscular atrophy (Kennedy's disease)

OBJECTIVE: To study tremor in patients with X-linked recessive spinobulbar muscular atrophy or Kennedy's disease. METHODS: Ten patients (from 7 families) with a genetic diagnosis of Kennedy's disease were screened for the presence of tremor using a standardized clinical protocol and followed up at a neurology outpatient clinic. All index patients were genotyped and showed an expanded allele in the androgen receptor gene. RESULTS: Mean patient age was 37.6 years and mean number of CAG repeats 47 (44-53). Tremor was present in 8 (80 percent) patients and was predominantly postural hand tremor. Alcohol responsiveness was detected in 7 (88 percent) patients with tremor, who all responded well to treatment with a β-blocker (propranolol). CONCLUSION: Tremor is a common feature in patients with Kennedy's disease and has characteristics similar to those of essential tremor.

Clinical and genetic analysis of a pedigree of Kennedy disease / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To review the clinical and genetic features of a pedigree of Kennedy disease in China.</p><p><b>METHODS</b>The clinical data of patients from a Kennedy disease family were collected. The numbers of trinucleotide CAG repeats in exon 1 of the androgen receptor gene were determined by DNA sequencing and repeat fragment analysis.</p><p><b>RESULTS</b>In the pedigree, 4 patients were identified as Kennedy disease. Clinical manifested with adult-onset, progressive proximal limb muscle weakness and atrophy, gynecomastia, oligospermia were also presented. The number of trinucleotide CAG repeats in exon 1 of the androgen receptor gene was 51 in the proband. The electrophysiological study showed sensory and motor involvement and their serum triglycerides values were elevated significantly.</p><p><b>CONCLUSION</b>Androgen receptors gene testing is the most reliable diagnosing method, the patients suspected as Kennedy disease should have a gene testing of androgen receptors.</p>

Study on clinical manifestation, genotype and genetic characteristics of two Kennedy disease pedigrees / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the clinical manifestations, genotypes, and genetic characteristics of two pedigrees with Kennedy disease.</p><p><b>METHODS</b>The clinical data of the patients from two Kennedy disease families were collected. The numbers of trinucleotide CAG repeats in exon 1 of the androgen receptor gene were determined by DNA sequencing and repeat fragment analysis.</p><p><b>RESULTS</b>Family A was composed of 58 individuals in 4 generations. The proband had onset at 39 years old. There were two Kennedy disease patients in family B which included 61 individuals in 5 generations. The two patients had onset at 39 and 41 years old, respectively. All the three patients displayed limbs and bulbar muscular weakness because of the damage of lower motor neurons. They had androgen insensitivity syndrome in common, and showed mild or moderate increase in serum creatine kinase level. The electromyogram showed wild damage in anterior horn of spinal cord. Muscle biopsy displayed neurogenic muscular atrophy. The numbers of the CAG repeat expansion in the androgen receptor gene of the three patients were 49, 48, and 47, respectively. X-linked recessive mode of inheritance was demonstrated by pedigree analysis in the two families.</p><p><b>CONCLUSION</b>Kennedy disease usually occurs in mid-adulthood man. The clinical features are the weakness and wasting of limbs and bulbar muscles. Genetic analysis contributes to diagnosis and identification of carriers, and is beneficial to genetic counseling and prenatal diagnosis.</p>

Kennedy Disease Showing Prominent Remyelinating Features of Sural Nerve

We report a 55-year-old man with chronic weakness of both legs with recently experienced nasal voice. Despite the absence of sensory symptoms, electrophysiologic studies revealed the presence of sensorimotor polyneuropathy. A sural-nerve biopsy showed remarkable reduction of large myelinated fibers with prominent remyelination. Intravenous immunoglobulin was administered due to suspected chronic demyelinating neuropathy, but had no effect. Abnormal trinucleotide-repeat expansion of the androgen receptor gene was subsequently detected in both the patient and his family. These observation indicate that prominent remyelinating features are not necessarily indicative of demyelinating neuropathy.

A Case Report of X-linked Recessive Bulbospinal Muscular Atrophy (Kennedy`s Syndrome)

We had 58-year-old-man with chronic lower back pain, progressive whole extremities and facial muscle weakness, dysarthria and recurrent aspiration during swallowing, without any sensory disturbance. His two brothers had similar symptoms from their 6th decade. He had muscle atrophy on tongue, both hand lower leg muscles with some fasciculations. All tendon reflexes were absent without pathologic pyramidal reflex. Nerve conduction studies revealed low median, ulnar, and sural sensory nerve action potential amplitude. On EMG study, there were chronic denervation potentials on most of muscles of extremities. On DNA analysis, there were abnormal expansions of CAG repeats in the androgen receptor gene. We confirmed a X-linked recessive bulbospinal muscular atrophy (Kennedy's syndrome).

Four cases of Kennedy's disease in three families earlier diagnosed as amyotrophic lateral sclerosis

Kennedys disease (KD) is a rare, slowly progressive neurodegenerative disorder of motor neurons in the spinal cord and brain stem. Most of the cases of KD in clinical practice are misdiagnosed. The knowledge of the initial presentation, the range of age within which the disease would manifest and the clinical course of the disease would be very helpful to better manage and anticipate the outcome of such cases. This report highlights the typical earliest presentation of KD and the clearcut clinical picture of KD that differentiates it from other motor neuron diseases of grave scenario and prognosis We report clinical details of 4 male patients with KD seen in our center. Diagnosis of these four patients were based on their clinical picture the time they were first seen. Common features in their history and presentation were the onset of prolonged and intermittent muscle cramps followed by weakness and atrophy of the muscles involved. All of them developed gynecomastia. Three of them have concomitant diabetes, and one has thyroid problem. All of them were initially diagnosed as Amyotrophic lateral Sclerosis.

X-linked Recessive Bulbospinal Muscular Atrophy (Kennedy's Syndrome): A case report

X-linked recessive bulbospinal muscular atrophy (Kennedy's syndrome) is a variant of the spinal muscular atrophies caused by mutation of androgen receptor gene on X-chromosome. A 69-year-old man had suffered from slowly progressive lower extremity weakness and gynecomastia. Muscle weakness was more severe in proximal muscles and showed symmetrical features. He had fascicular contraction on his face and tongue. All tendon reflexes were absent and pyramidal signs were not detected. Nerve conduction studies were normal except low amplitude of sensory nerve action potential in median nerve. Needle electromyography revealed widespread chronic denervation potentials in all sampling muscles of extremities, facial and tongue muscles. Histopathologic findings showed chronic denervation atrophy. DNA analysis showed abnormal expansion of CAG repeats in the androgen receptor gene and we confirmed this case as Kennedy's syndrome. If an adult patient has slowly progressive muscle weakness, bulbar symptoms and signs of male genital failure, DNA analysis should be taken to differentiate Kennedy syndrome from other motor neuron disease or myopathy.

A Case of Kennedy Syndrome Mimicking Myasthenia Gravis

Patients with Kennedy syndrome, which progresses more slowly than amyotrophic lateral sclerosis show a mild degree of motor fluctuation but rarely show significant decremental responses to repetitive nerve stimulations. Even in a patient with decremental responses to repetitive nerve stimulations, there is usually no significant improvements in motor symptoms to anticholinesterases. We experienced a patient with Kennedy syndrome, who showed significant decremental responses to repetitive nerve stimulations and a marked degree of motor fluctuation. His motor fluctuation responded dramatically to anticholinesterase. (J Korean Neurol Assoc 19(5):544~546, 2001)