Disclosures: William A. Berrigan, MD: Nothing to disclose

Objective: Develop and quantify a sensitive tool for evaluation of disease severity and progression in LOTS. Describe the appearance and pattern of muscle pathology in the disease.

Design: Initial musculoskeletal ultrasound findings within a natural history study of LOTS patients.

Setting: Clinical Research Center

Participants: 5 patients with age-matched controls. Ongoing period of enrollment.

Interventions: No intervention was performed. Diagnostic studies included ultrasound and shear wave muscle elastography for qualitative and quantitative data.

Main Outcome Measures: 2D muscle imaging and shear wave muscle elastography were used as objective measures of muscle atrophy and stiffness. Measurements were taken of the deltoid, biceps, triceps, quadriceps, medial hamstrings, tibialis anterior and lateral gastrocnemius muscles. Measurements included muscle thickness, qualification using the Heckmatt scale and shear wave data.

Results: 2D imaging revealed evidence of fatty infiltration and muscle atrophy in the deltoid, triceps, quadriceps, hamstrings, tibialis anterior, and gastrocnemius with a Heckmatt of 3-4. There was more selective involvement of the triceps and quadriceps. Elastography revealed increased stiffness most prominent in the triceps and rectus femoris.

Conclusions: Late Onset Tay Sachs is a rare autosomal recessive neurodegenerative disorder in which there is a deficiency hexosaminidase A leading to an accumulation of the Ganglioside GM2. Variability exists in clinical presentation, and includes proximal muscle weakness, ataxia, dysarthria, spasticity, dystonia, and tremor. Although muscle weakness, atrophy and peripheral neuropathy in patients with LOTS have been described, this is the first report of ultrasound to characterize the pattern of muscle involvement and integrity. We used 2D ultrasound and shear wave muscle elastography to objectively quantify the elasticity of musculoskeletal structures. Additional studies are ongoing with the goals of better characterizing the range of muscle involvement in LOTS, the impact of muscle involvement on function, and to develop objective measures of muscle pathology to track the natural history and response to treatments when this becomes available.

Level of Evidence: Level IV

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/qualitative-and-quantitative-skeletal-muscle-ultrasound-in-late-onset-tay-sachs-disease-lots/