Flail Arm Syndrome: An Atypical Variant of Motor Neuron Disease

Flail Arm Syndrome: An Atypical Variant of Motor Neuron Disease

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  A D EW I J A Y A , M D D E C E M B E R 2 0 2 3 Flail Arm Syndrome
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  Introduction  Flail ArmSyndrome (FAS) is an atypical form of Motor Neuron Disease (MND)  Synonim: Vulpian-Bernhardt syndrome, man-in-the barrel syndrome, or brachial amyotrophic diplegia Wijesekera LC, Mathers S, Talman P, Galtrey C, Parkinson MH, Ganesalingam J, Willey E, Ampong MA, Ellis CM, Shaw CE, Al-Chalabi A, Leigh PN (2009) Natural history and clinical features of the flail arm and flail leg ALS variants. Neurology 72(12):1087–1094. doi:10.1212/01.wnl.0000345041.83406.a2 Sasaki S, Iwata M (1999) Atypical form of amyotrophic lateral sclerosis. J Neurol Neurosurg Psychiatry 66(5):581–585 Katz JS, Wolfe GI, Andersson PB, Saperstein DS, Elliott JL, Nations SP, Bryan WW, Barohn RJ (1999) Brachial amyotrophic diplegia: a slowly progressive motor neuron disorder. Neurology 53(5):1071–1076
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  Clinical Presentation  Predominantlyproximal, progressive and symmetric wasting and paresis of the upper limb muscles, while lower limbs and bulbar muscles are spared Higher share of male patients than ALS (m:f = 4:1) Younger age of onset than ALS (mean age = 55 years) Prolonged survival compared to ALS (mean: 20 months) First manifestation most frequently distal and at the dominant side Couratier P, Truong C, Khalil M, Deviere F, Vallat JM (2000) Clinical features of flail arm syndrome. Muscle Nerve 23(4):646–648 Hübers A, Hildebrandt V, Petri S, Kollewe K, Hermann A, Storch A, Hanisch F, Zierz S, Rosenbohm A, Ludolph AC, Dorst J. Clinical features and differential diagnosis of flail arm syndrome. Journal of neurology. 2016 Feb;263:390-5.
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  Diagnosis Wijesekera LC, MathersS, Talman P, Galtrey C, Parkinson MH, Ganesalingam J, Willey E, Ampong MA, Ellis CM, Shaw CE, Al-Chalabi A. Natural history and clinical features of the flail arm and flail leg ALS variants. Neurology. 2009 Mar 24;72(12):1087-94.
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  Diagnosis  Clinical  Electrodiagnosticstudy  Genetic molecular investigation GAMEZ J, CERVERA C, CODINA A. Flail arm syndrome or VulpianBernhart’s form of amyotrophic lateral sclerosis. Journal of Neurology, Neurosurgery & Psychiatry. 1999 Aug 1;67(2):258-.
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  Electrodiagnostic Study  Similarfeature to ALS  Reduced split hand index in ALS  Split hand index: To calculate the SHI is by multiplying the CMAP amplitude recorded over the APB and FDI muscles, and dividing this product by the CMAP amplitude recorded over the ADM muscle, as follows: SHI = APB (CMAP) × FDI (CMAP)/ADM CMAP Yang H, Liu M, Li X, Cui B, Fang J, Cui L. Neurophysiological differences between flail arm syndrome and amyotrophic lateral sclerosis. PloS one. 2015 Jun 9;10(6):e0127601. LIU F, SONG C, LIU H, ZHANG M, FENG S, LI L. The clinical and electrophysiological characteristics of flail arm syndrome. Chinese Journal of Physical Medicine and Rehabilitation. 2021:21-4.
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  Differential Diagnosis  MultifocalMotor Neuropathy  Spinal Muscular Atrophy  Carpal Tunnel Syndrome  Herniated disc Hübers A, Hildebrandt V, Petri S, Kollewe K, Hermann A, Storch A, Hanisch F, Zierz S, Rosenbohm A, Ludolph AC, Dorst J. Clinical features and differential diagnosis of flail arm syndrome. Journal of neurology. 2016 Feb;263:390-5.
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  Treatment  No cure Supportive / symptomatic treatment
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  Summary  FAS isan atypical form of Motor Neuron Disease  Predominantly proximal, progressive and symmetric wasting and paresis of the upper limb muscles  Diagnosis: Clinical, electrodiagnostic, genetic  No cure  Prognosis better than ALS
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