MUSCLE STRUCTURE AND FUNCTION IN PEOPLE WITH DISTAL HEREDITARY MOTOR NEUROPATHY: LONGITUDINAL STUDY

Aljwhara Alangary, Chia-Chen Chou, Agustin Montt Rodriguez, Mary M Reilly, Gita Ramdharry, Jasper Morrow, Matilde Laura, Alexande Rossor
Purpose:
  • To describe patterns of muscle involvement and gait deviations in people with DHMN in comparison to healthy controls.
  • To explore the progression of DHMN over one year and to assess the responsiveness of the quantitative methods used to determine predictors of change.
Methods:
  • To identify patterns of involvement, comparisons of 12 DHMN and 9 matched healthy control parameters of MRI, dynamometry, and motion analysis using unpaired t-test or Mann-Whitney U test.
  • To explore the natural history of muscle structure and function in DHMN over one year, 8 DHMN participants repeated the same measurements after 6 and 12 months. Follow-up values were compared using repeated measures analysis of variances. The standardised response mean (SRM) was used to explore the sensitivity of the outcome measures.
Results:

Pattern of Involvement (difference between DHMN and control):

- MRI Muscle fat fraction showed differences at the foot (P0.0001), and the total calf (P=0.0007).

- The remaining muscle area showed difference at the foot (P=0.0038) and the calf (P=0.0126) mainly in the plantar flexors (P=0.0082).

- Dynamometry showed differences in isometric dorsiflexion10° (P=0.0134), 30° (P=0.0121), and isokinetic plantarflexion (P=0.0062).

- DHMN group walked slower(P=0.0322) with more stride time (P=0.0279). 

- kinematics showed higher dorsiflexion angle (P=0.0435) in stance phase, and lower plantar flexion angle (P=0.0259) at pre-swing. Higher hip flexion angle (P=0.0076) was observed in swing.

- Kinetics at terminal stance showed lower ankle plantar flexion moment (P=0.0002) and lower ankle power generation (P=0.0011). There was significant reduction in ankle power generation in swing phase (p=0.0279).

Longitudinal Change:

- MRI muscle fat fraction increased at the calf (P=0.003) and the remaining muscle area showed reduction in the total plantar flexors (P=0.048).

- Differences was shown in isometric dorsiflexion (P=0.009) and isokinetic plantarflexion (P=0.031) strength with an increase in mean ankle strength.

- Gait parameters didn’t show significant change over 12 months.

- Calf muscles MRI fat fraction was the most responsive to change, with SRM ranging from 1.1 to 1.78.

Conclusion(s):

We present a DHMN cohort showing greater plantar flexor muscle involvement. This was associated with reduced ankle torque, stride length, and ankle power in comparison to controls. The longitudinal study results suggest that DHMN is a slowly progressive condition and although 3D motion analysis is a valuable tool in describing function and detecting deviation from normal, quantitative MRI is more sensitive to differences over time.

Implications:

By evaluating the impact of the disease on function, the results will guide health practitioners and clinical experts on how to improve patient care and maximise walking and mobility function. The data provides effect size data to conduct sample size calculations for larger observational studies and trials.

Funding acknowledgements:
Alangary is funded by SaudiArabian Cultural Bureau in UK. This research was supported by the NIHR UCLH Biomedical Research Centre.
Keywords:
Gait analysis
MRI
DHMN
Primary topic:
Neurology
Second topic:
Research methodology, knowledge translation and implementation science
Third topic:
Musculoskeletal: lower limb
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
Institution: NHS Ethics committee: Research Ethics Committee
Provide the ethics approval number:
20/LO/0519
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

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