October 5, 2020, e-Pearl of the Week: Isolated Bulbar Amyotrophic Lateral Sclerosis (IBALS)

Isolated Bulbar Amyotrophic Lateral Sclerosis (IBALS)

Isolated Bulbar Amyotrophic Lateral Sclerosis (IBALS), regional ALS variant, presents with insidious onset dysarthria, dysphagia, pseudobulbar affect with initially preserved respiratory function. Pathological signs include jaw hyperreflexia, tongue fasciculation, and Hoffman’s sign. IBALS constitutes 4% of motor neuron disease and is more prevalent in females with a slightly delayed mean age of onset compared to typical ALS (61 vs 58 years).1,2 Electrodiagnostic studies show denervation changes restricted to bulbar muscles (fibrillation potentials, positive sharp waves, large polyphasic motor units) with preserved CMAP amplitudes in limbs. Diagnostic work-up includes MRI brain/cervical spine. Differentials include bulbar-onset ALS, myasthenia gravis, and space-occupying bulbar lesions. Lack of progression for six-months distinguishes IBALS from bulbar-onset ALS. Multimodality management includes symptomatic such as Dextromethorphan/quinidine for pseudobulbar affect and supportive measures including gastrostomy in early stages and PAP therapy in advanced stages.3 Efficacy of riluzole has not been studied in IBALS. Survival rate is better than bulbar onset ALS (75% vs 45% at 54 months).1

References

  1. Jawdat O, Statland J, Barohn R, Katz J, Dimachkie M. Amyotrophic Lateral Sclerosis Regional Variants (Brachial Amyotrophic Diplegia, Leg Amyotrophic Diplegia, and Isolated Bulbar Amyotrophic Lateral Sclerosis). Neurol Clin 2015;33:775–785.
  2. Talbott EO, Malek AM, Lacomis D. The epidemiology of amyotrophic lateral sclerosis. Handb Clin Neurol 2016:225–238.
  3. Smith R, Pioro E, Myers K et al. Enhanced Bulbar Function in Amyotrophic Lateral Sclerosis: The Nuedexta Treatment Trial. Neurotherapeutics 2017;14:762–772.

Submitted by Maryam Bahadori, MD, Tehran University of Medical Sciences (Tehran, Iran), and Faisal Khan MD, DABSM, DABPN, Consultant Neurologist, Sugarland Neurology and Sleep Texas (Sugar Land, Texas)

Maryam Bahadori and Dr. Khan report no disclosures.