Dorsal Rhizotomy at the Intradural Juxtaforaminal Zone.

Abstract

To optimize the efficacy of dorsal rhizotomy (DRh) in treating spasticity associated with cerebral palsy, the authors advocate for individual access (intradurally) to all roots from L2 to S2. The initial step involves the use of electrical stimulation of the ventral root (VR) to confirm their anatomical identity and determine their corresponding myotomal territory of innervation, which is known to exhibit interindividual variability (anatomical mapping). The primary objective is then to employ dorsal root (DR) stimulation to assess their respective reflexive excitability levels (physiological testing). To mitigate the risk of spine destabilization, access is gained through enlarged interlaminar openings while preserving the spinous processes and interspinous ligaments. This approach is termed Keyhole Interlaminar Dorsal rhizotomy (KIDr). Intradural access to the roots is achieved at their preforaminal zone, through a L1-L2 opening for the L2 and L3 roots, L3-L4 opening for the L4 and L5 roots, and L5-S1 opening for the L5 and S1 roots. Under microsurgical visualization, at each exposed root level, the VR is stimulated to verify its myotomal distribution, and the DR is stimulated to estimate the segmental reflexive excitability using Fasano's grading system, allowing for the adjustment of the number of rootlets per root to be severed. In our practice, indications are primarily based on the Gross Motor Function Classification System (GMFCS): for individuals classified as levels III and IV, the goal is to enhance functional status and prevent or halt deformities; for those at level V and quadriplegic patients, the aim is to improve comfort, reduce pain, facilitate care, and alleviate upper limb disability through the "distant effects" often observed following lumbo-sacral rhizotomy. The timing of surgery is determined not only by age-related locomotor development but also by the plateau or deterioration of the Gross Motor Function Measure (GMFM) curve despite intensive rehabilitation efforts. As with all specialized centers, the surgical schedule is established in collaboration with a multidisciplinary team and documented in a comprehensive chart, alongside the Gain Attainment project.