title: Involuntary rhythmic leg movements time-locked with the respiratory cycle.
abstract: Involuntary rhythmic leg movements in childhood is an uncommon condition, the generators of which remain unknown. We report on a male 3 years of age with distinct features providing important clues concerning the location of one of these generators. At the age of 7 months, the previously healthy young male started with low frequency, rhythmic, and continuous (both during wakefulness and sleep) flexion/extension movements of the lower limbs. Movements interfered significantly with gait acquisition, and, despite normal cognitive development, he was able to walk only at age 2 years, 4 months. The neurologic examination revealed the absence of automatic stepping in the neonatal period, but was otherwise normal. A polygraphic electroencephalogram/electromyogram (EEG/EMG) recording, at the age of 2 years, 9 months, revealed rhythmic and synchronous legs with EMG activity at 0.5 Hz. A more complete polygraphic recording at the age of 3 years, 10 months, showed a lower frequency (0.35 Hz) for the movements, which were time-locked with the respiratory cycle. Magnetic resonance imaging (MRI) of the brain revealed an increased T(2) signal in the upper medulla-lower pons regions. The generator of the rhythmic legs movements is postulated to be the respiratory center, connecting with the reticulospinal projecting neurons through an aberrant pathway.
authors.affiliation: Department of Neurology, Hospital Fernando Fonseca, Lisbon, Portugal.
authors.forename: A J
authors.initials: AJ
authors.lastname: Leal
authors.forename: E
authors.initials: E
authors.lastname: Calado
mesh_terms: D002675:Child, Preschool; D020820:Dyskinesias / Q000151:congenital / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007866:Leg / Q000294:innervation; D008279:Magnetic Resonance Imaging; D008297:Male; D008526:Medulla Oblongata / Q000473:pathology / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000294:innervation; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology; D009460:Neurologic Examination; D011149:Pons / Q000473:pathology / Q000503:physiopathology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012125:Respiratory Center / Q000473:pathology / Q000503:physiopathology*; D013116:Spinal Cord / Q000473:pathology / Q000503:physiopathology