Adolescent idiopathic scoliosis (AIS) affects 2-4% of adolescents worldwide, yet 80% of cases remain classified as "idiopathic." This integrative review proposes the neural generation hypothesis: AIS may be generated by the body schema -- the brain's non-conscious predictive model of the body -- operating on degraded sensory input during a critical developmental window. The curve persists because the rate of schema updating, constrained by low proprioceptive precision, falls below the rate of skeletal change during adolescent growth. Six convergent lines of empirical evidence are synthesized within the active inference computational framework: (1) the primary AIS susceptibility gene LBX1 specifies somatosensory interneurons involved in proprioceptive integration, not bone; (2) a 2024 CRISPR mouse model demonstrated proprioceptive deficits before vertebral rotation; (3) proprioceptive processing is degraded in AIS; (4) sensory reweighting toward vestibular input is consistent with Bayesian compensation for degraded proprioception; (5) body schema distortion is documented but systematically under-researched; and (6) altered postural sway and cortical processing reveal the prediction system in real time. Four AIS susceptibility genes (LBX1, PAX1, GPR126, CHD7) collectively degrade the somatosensory relay layer involved in proprioceptive integration (LBX1), structural substrate including growth plate and cartilage/IVD integrity (PAX1 and GPR126), and epigenetic regulation (CHD7). Independent experimental convergence from Domenech et al. demonstrates that unilateral somatosensory cortex ablation alone produces scoliosis in developing rats (46% incidence, avg. 23 degrees Cobb), confirming that the mechanism begins in sensation, not structure. Self-reinforcing precision, autonomic, and psychosocial loops maintain the curve as a stable attractor state. Eight testable predictions are proposed, including body schema precision correlation with curve severity, genotype-proprioception correlation in existing cohorts, a prospective screening study, and cross-condition generalization to kyphosis, chronic low back pain, and amblyopia. The "idiopathic" designation may reflect a measurement gap: current diagnostic tools assess the structural output while the generating mechanism operates across the nervous system, the epigenetic landscape, and the autonomic state.
Samuel Aza Miller (Mon,) studied this question.