Adult Spinal Muscular Atrophy (Atrophy Myelopathic Muscular)

Adult spinal muscular atrophy is a genetic neurodegenerative disorder characterized by muscle wasting and weakness. In adults, normal life expectancy is achieved, as only mild weakness may be encountered. The diagnosis rests on confirming genetic mutations.


Presentation

Adult spinal muscular atrophy or spinal muscular atrophy (SMA) type 4 usually begins to appear at 30 years of age and has a relatively benign course [1]. The clinical features of this disease are very similar to SMA type 3, although the adult version is less severe. Life expectancy is normal in such patients [2]. Type 1 and type 2 SMA can occur at any age between birth and 2 years.

Patients classically present with an asymmetric weakness of the proximal muscles of the arms and legs, resulting in hampering of the quality of life [3]. Over time, the muscle wasting spreads to the other limb muscles before involving the central portions of the body. The weakness is associated with pain, in both the normal and affected muscles. Tremors and twitchings are also known to occur [4].

Involvement of the muscles of the thorax may result in respiratory compromise. The affliction of the brainstem may lead to bulbar symptoms such as dysphagia and dysarthria. There are usually no other central nervous system manifestations present. Reports have shown that these patients exhibit a higher degree of intelligence.

The examination may show all the characteristic findings of a lower motor neuron disease, namely absent/decreased reflexes, hypotonia, flaccid paralysis and muscle fasciculations.

musculoskeletal
Muscular Atrophy
  • Diagnosis - Adult-onset spinal muscular atrophy Prognosis - Adult-onset spinal muscular atrophy Treatment - Adult-onset spinal muscular atrophy Resources - Adult-onset spinal muscular atrophy Not supplied.[checkorphan.org]
  • About Spinal Muscular Atrophy (SMA) About SMA Spinal Muscular Atrophy (SMA) refers to a group of genetic conditions that cause muscle weakness and atrophy in children and adults.[griswoldhomecare.com]
  • Molecular pathology Defects of SMN1, which encodes a survival motor neuron protein, cause spinal muscular atrophy types 1–4.[medical-dictionary.thefreedictionary.com]
Muscle Weakness
  • Muscle weakness seen in SMA4 is similar to the muscle weakness seen in other genetic conditions.[resourcerepository.org]
  • SMAPAD is characterized by proximal muscle weakness that begins in the lower limbs and then progresses to upper limbs, onset in late adulthood (after third decade) and a benign course.[uniprot.org]
  • […] spinal muscular atrophy type 4 An autosomal recessive condition (OMIM:271150) characterised by symmetrical proximal muscle weakness and atrophy.[medical-dictionary.thefreedictionary.com]
  • The nerve cells tend to cause muscle weakness, tremor, and twitching.[patientslikeme.com]
  • Often it is not muscle weakness but muscle contracture which causes the inability to walk.[daneverard.co.uk]
Muscle Twitch
  • twitching first noted in late teens or early adulthood There are other diseases that are similar to spinal muscular atrophy, but have different genetic causes.[togetherinsma.com]
  • twitches and weakness of limb muscles As the condition progresses: Weakness of the face and tongue muscles which may cause difficulties when swallowing and speaking Recurring pneumonia Some patients also develop enlarged male breasts (gynaecomastia),[thehumanthebody.com]
  • twitching first noted in late teens or adulthood To learn how different aspects of care may relate to the signs and symptoms of SMA, click here .[togetherinsma-hcp.com]
  • The initial symptoms of Kennedy’s syndrome may include tremor (shaking) of the hands, muscle cramps on exertion, muscle twitches and weakness of the muscles of the limbs.[your.md]
Myopathy
  • , Multicore myopathy, Multiminicore myopathy, Minicore myopathy with hand involvement, antenatal onset minicore myopathy with arthrogryposis, Minicore myopathy with external ophthalmoplegia, Multicore myopathy with external ophthalmoplegia, Multiminicore[orphananesthesia.eu]
  • Differential diagnosis Motor neurone disease Primary lateral sclerosis Muscular dystrophy Congenital myopathies Disorders of carbohydrate metabolism ( glycogen storage diseases ) Myasthenia gravis Poliomyelitis Investigations Blood tests Creatine kinase[patient.info]
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  • gastrointestinal
    Dysphagia
    • Dysphagia may be present.[merckmanuals.com]
    • As the condition progresses, it may cause other symptoms, including: weakness of the facial and tongue muscles, which may cause difficulty swallowing ( dysphagia ) and slurred speech recurring pneumonia (infection of lung tissue) Some people with Kennedy[your.md]
    • […] associated with names of investigators such as Santavuori-Haltia, Jansky-Bielschowsky, Batten, Spielmeyer-Vogt, Kufs Opitz G/BBB Syndrom ( 1 Files ) Erkrankung : Opitz G/BBB Syndrom ICD 10: Q87.8 Synonyme : Hypertelorism-hypospadias syndrome, hypospadias-dysphagia[orphananesthesia.eu]
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  • neurologic
    Tremor
    • Other symptoms include tremors, twitching, and mild breathing issues.[resourcerepository.org]
    • The nerve cells tend to cause muscle weakness, tremor, and twitching.[patientslikeme.com]
    • Symptoms – Children can stand alone and walk, but may struggle with: getting up from a sitting position tremor in fingers respiratory infections Children with SMA Type III usually remain mobile well into adulthood.[griswoldhomecare.com]
    • […] usually able to sit unattended, but cannot stand or walk without assistance Weak respiratory muscles, which can inhibit coughing Breathing problems Weakness in the muscles of the arms and especially of the legs Swallowing and feeding problems Slight tremor[thehumanthebody.com]
    • Fine tremors of the face are present in over 90% of patients.[encyclopedia.com]
    Limb Weakness
    • As the disease progresses patients may notice limb weakness starting in the pelvis or shoulders, or weakness of the facial and tongue muscles.[cedars-sinai.edu]
    • The condition is also called bulbospinal muscular atrophy and Kennedy's disease. ... more » Symptoms of Adult SMA Progressive limb weakness Limb muscle atrophy Difficulty speaking Difficulty swallowing Respiratory problems more symptoms...»[rightdiagnosis.com]
    • […] reported so far) Etiology : defect in VRK1 gene on chromosome 14q atrophy of the cerebral cortex, cerebellar and brain stem hypoplasia, absent dendate nucleus, loss of neurons in the basal ganglia Clinical features Onset at 0–6 months Early Arthrogryposis Limb[amboss.com]
    • In addition to muscle weakness, clinical features include head lag, poor sucking and swallowing, weak cry, proximal limb weakness, and lack of reflexes.[encyclopedia.com]
    Absent Deep Tendon Reflex
    • Results in muscle weakness and atrophy The onset varies from before birth until adulthood The weakness is symmetric and progressive Contractures, usually mild Anterior horn cell involvement, apparent due to tongue fasciculations and absent deep tendon[en.wikibooks.org]
    • deep tendon reflexes Severe bulbar palsy Respiratory failure Atrophy and fasciculations in the tongue Weak cry and cough Inability to swallow difficulty feeding, drooling, risk of aspiration Delayed motor milestones Poor weight gain Weak cough Fine hand[amboss.com]
    Areflexia
    • Patients typically present during infancy or early childhood with progressive weakness, hypotonia , muscle atrophy , hyporeflexia/areflexia, and varying degrees of bulbar weakness.[amboss.com]
    Average Intelligence
    • The brain is not affected, and they have been tested to have at least average to above average intelligence.[smasupport.com]
    Flaccid Paralysis
    • Genetic testing for non-5q spinal muscular atrophy References: [1] Differential diagnoses Certain viral infections ( polio , coxsackievirus, echovirus, West Nile virus ) much more acute onset of flaccid paralysis, ascending paralysis (i.e., starts distally[amboss.com]
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  • Entire body system
    Difficulty Walking
    • The mobility component is paid to people who have difficulty walking and in using public transport; the personal care component is paid to those who need help with such tasks as bathing and dressing.[daneverard.co.uk]
    • Someone with the condition may have: weakness in the hands and feet difficulty walking shaking and twitching muscles Type 4 SMA gets slowly worse over time, but doesn't normally cause problems with breathing or swallowing.[nhs.uk]
    • walking Breathing and swallowing difficulties are very rare and the condition does not usually affect life expectancy Over time, muscles become weaker resulting in children potentially losing their ability to walk when older SMA type IV – adult onset[thehumanthebody.com]
    • These children show signs of clumsiness, difficulty walking, mild muscle weakness, and may be developmentally delayed.[chw.org]
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  • Workup

    Diagnosis of this disease is dependent on the anamnestic data. Amongst laboratory tests that may be performed, creatine kinase is the most useful, with elevated levels of the enzyme found. In some patients, the enzyme levels may be normal.

    Genetic tests may be performed both prenatally and postnatally to check for deletions involving the SMN1 gene [5].

    Electrocardiograms (ECGs) are usually normal in these patients [6].

    A variety of other neuromuscular diseases may present in a similar manner. Differentiation is done by electrophysiological tests that demonstrate a reduction of transmitted nerve signals [7] [8]. Sensory signals are usually normal in adult spinal muscular atrophy. Tests involving compound motor action potential may also be performed for diagnosis.

    Muscle biopsy is another test that may help in differentiating adult spinal muscular atrophy from other similar muscular diseases [9] [10]. These characteristically show atrophy of the muscle fibers with compensatory hypertrophy.

    Differential diagnosis usually involves the other spinal muscle atrophies which include the X-linked spinal muscular atrophy, distal spinal muscular atrophy, autosomal dominant spinal muscular atrophy and juvenile asymmetric segmental spinal muscular atrophy. Postpolio syndrome and multifocal motor neuropathy are the other conditions that may present in a similar fashion.

    There is a potential for patients with adult spinal muscular atrophy to be misdiagnosed due to the overlapping of clinical features. Over the years, patients labeled earlier as SMA have had their diagnoses revised to more treatable conditions including syringomyelia, amyotrophic lateral sclerosis, myopathy, axonal neuropathies and herniated lumbar discs. It is hence, recommended that patients be followed up for a long duration to establish the correct diagnosis.

    Pathology

    Other Pathologies
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  • Biopsy
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  • Treatment

    Prognosis

    Complications

    Amyotrophic Lateral Sclerosis
    • . : Motor neuron disease (Amyotrophic lateral sclerosis) .[link.springer.com]
    • A distinction should be made between Adult Onset SMA which affects the lower motor neurones and Motor Neurone Disease (Amyotrophic Lateral Sclerosis or ALS) which affects both the upper and lower motor neurones.[daneverard.co.uk]
    • lateral sclerosis 2016 2017 2018 Billable/Specific Code Adult Dx (15-124 years) spinal G12.25 ICD-10-CM Diagnosis Code G12.25 Progressive spinal muscle atrophy 2018 - New Code Billable/Specific Code adult G12.1 adult G12.1 spinal G12.9 ICD-10-CM Diagnosis[icd10data.com]
    • Differential diagnosis Differential diagnoses include the amyotrophic lateral sclerosis, primary lateral sclerosis, myasthenia gravis, and carbohydrate metabolism disorders (see these terms).[orpha.net]
    Motor Neuron Disease
    • Electrophysiological studies showed patterns of lower motor neuron disease and genetic test showed P56S mutation of VAPB gene.[neurology.org]
    • ADULT-ONSET SPINAL MUSCULAR ATROPHY: PDF Only 1997 American Academy of Neurology Source CONTINUUM: Lifelong Learning in Neurology3(1, Motor Neuron Diseases):33-40, January 1997.[journals.lww.com]
    • People are sometimes told they have a motor neurone disease and assume they have ALS.[daneverard.co.uk]
    • In: Human motor neuron diseases p. 1–11.[link.springer.com]
    • neuron disease G12.21 Amyotrophic lateral sclerosis G12.22 Progressive bulbar palsy G12.23 Primary lateral sclerosis G12.24 Familial motor neuron disease G12.25 Progressive spinal muscle atrophy G12.29 Other motor neuron disease G12.8 Other spinal muscular[icd10data.com]

    Etiology

    Epidemiology

    Sex distribution
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    References

    1. Wang CH1, Finkel RS, Bertini ES, et al. Consensus statement for standard of care in spinal muscular atrophy. J Child Neurol. 2007;22(8):1027-1049.
    2. Baioni MT, Ambiel CR. Spinal muscular atrophy: diagnosis, treatment and future prospects. J Pediatr (Rio J). 2010;86(4):261-270.
    3. Prior TW, Russman BS. Spinal Muscular Atrophy. 2000 Feb 24 [Updated 2013 Nov 14]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016.
    4. Joynt R, Griggs R. Clinical Neurology. Philadelphia: Lippincott; 1997. Vol 4: 11-5.
    5. Arnold WD, Kassar D, Kissel JT. Spinal Muscular Atrophy: Diagnosis and Management in a New Therapeutic Era. Muscle Nerve. 2015;51(2):157-167.
    6. Palladino A, Passamano L, Taglia A, et al. Cardiac involvement in patients with spinal muscular atrophies. Acta Myol. 2011 Dec. 30(3):175-8.
    7. Hausmanowa-Petrusewicz I, Karwanska A. Electromyographic findings in different forms of infantile and juvenile proximal spinal muscular atrophy. Muscle Nerve. 1986 Jan. 9(1):37-46.
    8. Krivickas LS. Electrodiagnosis in neuromuscular disease. Phys Med Rehabil Clin N Am. 1998 Feb. 9(1):83-114, vi.
    9. Buchthal F, Olsen PZ. Electromyography and muscle biopsy in infantile spinal muscular atrophy. Brain. 1970. 93(1):15-30.
    10. Dubowitz V. Muscle disorders in childhood. Major Probl Clin Pediatr. 1978. 16:iii-xiii, 1-282.

    1. A Drosophila melanogaster model of spinal muscular atrophy reveals a function for SMN in striated muscle - TK Rajendra, GB Gonsalvez, MP Walker - The Journal of cell , 2007 - jcb.rupress.org
    2. Vulnerability of motor neurons and dissociation of pre-and post-synaptic pathology at the neuromuscular junction in mouse models of spinal muscular atrophy - LM Murray, LH Comley, D Thomson - Human molecular , 2008 - Oxford Univ Press
    3. A controlled trial of riluzole in amyotrophic lateral sclerosis - G Bensimon, L Lacomblez - New England Journal of , 1994 - Mass Medical Soc
    4. A family with adult spinal and bulbar muscular atrophy, X-linked inheritance and associated testicular failure - T Arbizu, J Santamaría, JM Gomez, A Quílez - Journal of the , 1983 - Elsevier
    5. A family with adult spinal and bulbar muscular atrophy, X-linked inheritance and associated testicular failure - T Arbizu, J Santamaría, JM Gomez, A Quílez - Journal of the , 1983 - Elsevier
    6. Degeneration in Portuguese families of the Azores Islands A new genetic disorder involving cerebellar, pyramidal, extrapyramidal and spinal cord motor functions - P Coutinho, C Andrade - Neurology, 1978 - AAN Enterprises
    7. A mutation in the vesicle-trafficking protein VAPB causes late-onset spinal muscular atrophy and amyotrophic lateral sclerosis - AL Nishimura, M Mitne-Neto, HCA Silva - The American Journal of , 2004 - Elsevier
    8. Benign spinal muscular atrophy arising in childhood and adolescence - D Gardner-Medwin, P Hudgson, JN Walton - Journal of the neurological , 1967 - Elsevier
    9. A family with adult spinal and bulbar muscular atrophy, X-linked inheritance and associated testicular failure - T Arbizu, J Santamaría, JM Gomez, A Quílez - Journal of the , 1983 - Elsevier
    10. Vulnerability of motor neurons and dissociation of pre-and post-synaptic pathology at the neuromuscular junction in mouse models of spinal muscular atrophy - LM Murray, LH Comley, D Thomson - Human molecular , 2008 - Oxford Univ Press
    11. A mutation in the vesicle-trafficking protein VAPB causes late-onset spinal muscular atrophy and amyotrophic lateral sclerosis - AL Nishimura, M Mitne-Neto, HCA Silva - The American Journal of , 2004 - Elsevier
    12. A family with adult spinal and bulbar muscular atrophy, X-linked inheritance and associated testicular failure - T Arbizu, J Santamaría, JM Gomez, A Quílez - Journal of the , 1983 - Elsevier
    13. A mouse model of spinal and bulbar muscular atrophy - , PJ Crack, I Kola, SS Cheema, MK Horne - Human molecular , 2002 - Oxford Univ Press
    14. A family with adult spinal and bulbar muscular atrophy, X-linked inheritance and associated testicular failure - T Arbizu, J Santamaría, JM Gomez, A Quílez - Journal of the , 1983 - Elsevier

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