Sensorimotor function and axonal integrity in adrenomyeloneuropathy.
BACKGROUND
Gait abnormalities and sensorimotor disturbances are principal defects in adrenomyeloneuropathy (AMN). However, to our knowledge, their association with overall impairment and neuroanatomical changes has not been defined.


OBJECTIVE
To understand how sensorimotor impairments create mobility deficits and to analyze how these impairments are related to specific metrics of axonal integrity.


METHODS
Cross-sectional study assessing impairments, including vibration sensation, strength, spasticity, and global measures of walking and balance. Fractional anisotropy was measured to evaluate the integrity of the corresponding brainstem tracts.


METHODS
Men with AMN and healthy control subjects.


RESULTS
Individuals with sensory loss only showed minimal walking deficits. Concomitant strength and sensory loss resulted in slower walking, with abnormal knee control; increased spasticity led to an exaggerated trunk motion and a knee-flexed (crouched) posture. Hip strength was an independent predictor of walking velocity in subjects with AMN. Subjects with sensory loss only had greater sway amplitudes during standing balance testing, which did not worsen with additional impairments. There were significant associations among sway amplitude, great toe vibration sense, and dorsal column fractional anisotropy. Brainstem fractional anisotropy in AMN was significantly negatively correlated with impairment, indicating that overall tract integrity is associated with sensorimotor abnormalities in AMN.


CONCLUSIONS
Impairment measures capture specific abnormalities in walking and balance that can be used to direct rehabilitation therapy in AMN. Tract-specific magnetic resonance imaging metrics, such as fractional anisotropy (used herein to evaluate structure-function relationships), significantly reflect disease severity in AMN.
Zackowski
Kathleen M
KM
Kennedy Krieger Institute, The Johns Hopkins University; Baltimore, MD 21205, USA.
Dubey
Prachi
P
Raymond
Gerald V
GV
Mori
Susumu
S
Bastian
Amy J
AJ
Moser
Hugo W
HW
D000326:Adrenoleukodystrophy / Q000473:pathology / Q000503:physiopathology; D000328:Adult; D001369:Axons / Q000473:pathology*; D001696:Biomechanical Phenomena; D001933:Brain Stem / Q000473:pathology*; D003430:Cross-Sectional Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008875:Middle Aged; D004856:Postural Balance / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D020886:Somatosensory Disorders / Q000209:etiology*