Selective dorsal rhizotomy: current state of practice and the role of imaging

Abstract

Spastic diplegic cerebral palsy (CP) is the most common form of CP. A specific goal-oriented approach, tailored to the child, is essential to management in all forms of CP. Selective dorsal rhizotomy (SDR) is a neurosurgical procedure that permanently reduces lower limb spasticity in children with spastic diplegic CP. The current technique is performed through a single level laminectomy at the level of the conus and, with the aid of intraoperative electromyography (EMG), allows selective division of the afferent lumbosacral nerve roots. In carefully selected children, reduction in spasticity has positive effects on the growing child. SDR is associated with minimal complications and good long-term outcomes. This article describes the surgical technique and patient selection, including the importance of medical imaging, and discusses the long-term outcomes of SDR.

Keywords: Cerebral palsy (CP); neuroimaging; neurosurgery; pediatrics; selective dorsal rhizotomy (SDR).

Figure 1

Typical features of PVL with white matter scarring in the deep and periventricular white matter bilaterally (yellow arrows), reduced thalamic volume (middle picture) and reduction in the bulk of the cerebral white matter posteriorly (red arrow pointing at the reduced bulk of the corpus callosum posteriorly). This is a good candidate for SDR given the lack of extensive anterior white matter involvement and sparing of the basal ganglia structures. PVL, periventricular leukomalacia; SDR, selective dorsal rhizotomy.

Figure 2

More severe case of PVL with more extensive scarring. Note the scalloping of the lateral ventricular margins, and the involvement of the posterior limbs of the internal capsules and thalami (yellow arrow). SDR outcome not judged to be favourable. PVL, periventricular leukomalacia; SDR, selective dorsal rhizotomy.

Figure 3

Case of neonatal encephalopathy, born at 36+4 with placental abruption in poor condition. Note the extensive white and grey matter involvement, involving also the basal ganglia. Not judged to be a favourable candidate for potential SDR in the future as the likelihood of developing dystonia secondary to basal ganglia involvement is high in such cases. SDR, selective dorsal rhizotomy.

Figure 4

The current SDR technique. (A) The single level laminectomy; (B) the plane between the dorsal and ventral nerve roots; (C) dorsal nerve roots are collected in a sling in order to expose the ventral motor roots; (D) peacock probes are used to systematically stimulate the dorsal roots from lateral (L2), to medial (S1). SDR, selective dorsal rhizotomy.