Selective Dorsal Rhizotomy in Cerebral Palsy- Selection and Physiotherapeutic Management

Selective Dorsal Rhizotomy (SDR) is a neurosurgical procedure that aims to:

• Reduce spasticity that interferes with motor function in children with spastic Cerebral Palsy.
• Improve function and mobility
• Increase independence
• Increase range of motion and improve positioning

(Verity, 2017 and Nordmark et al., 2008)

Funding in the UK:

The SDR procedure is not currently available on the NHS as funding for the surgery has been withdrawn whilst NHS England examines its effectiveness via a process called Commissioning Through Evaluation.  There are 7 funded centres: Alder Hey Children’s NHS Foundation Trust; The Portland Hospital for Women and Children; Great Ormond Street Hospitals NHS Foundation Trust; Leeds Teaching Hospitals NHS Trust; Nottingham University Hospitals NHS Trust; University Hospitals Bristol NHS Foundation Trust; The Robert Jones and Agnes Hunt Orthopaedic Hospital NHS (Scope UK, 2018). They undertake approximately 120 SDR cases a year (NHS England, 2014) with selected children to gather detailed information about clinical outcomes to produce a final report in Autumn 2018. Despite this SDR can be self-funded in the UK through the NHS hospital treatment top-up scheme. (Verity, 2017). In the UK the procedure costs between £30,000- £40,000 (The Portland Hospital, 2015).

Clinically relevant anatomy:

Two groups of nerve roots leave the spinal cord through the intervertebral foramen: the ventral and dorsal spinal roots (St. Louis Children’s Hospital, 2018). The ventral nerve roots are efferent motor roots and are responsible for control of muscular contractions, hormone synthesis and gland secretion. The dorsal nerve roots are afferent sensory roots and are responsible for the transmission of sensory stimulation to the CNS (Laser Spine Institute, n.d.). The SDR procedure decreases sensory stimulation to the CNS by dividing the dorsal nerve roots whilst preserving voluntary movement (NHS England, 2013).

Procedure:

The operation takes place under general anaesthetic and lasts approximately 5 hours (NICE, 2006). The procedure involves dividing some of the lumbar sensory nerve roots in order to reduce the sensory input to the sensory–motor reflex arcs which are responsible for increased muscle tone. A laminectomy of one or more vertebrae from L1 to S1 vertebrae  is performed to expose the dural sac (Funk and Haberl, 2016), which is opened to display the spinal conus with or without the cauda equina. The sensory nerve roots are identified intraoperatively using electrical stimulation, those that generate unusual electrical activity are thought to be those which contribute to spasticity. The selected sensory rootlets are divided, preserving some sensory supply and the motor roots responsible for voluntary movements (NICE, 2010). Up to 50% of the sensory nerve at each level is divided. (The Robert Jones and Agnes Hunt Orthopaedic Hospital, 2014). SDR is common in North America however there are significant variations between centers in the way the procedure is carried out (Steinbok, 2007).

For a descriptive video of the procedure follow this link to Dr. Samuel Brown discussing Selective Dorsal Rhizotomy (Seattle Children’s SDR Channel, 2017).

https://www.youtube.com/watch?v=HFad8MiTK_g

Diagram of the Selective Dorsal Rhizotomy procedure (St. Louis Children’s Hospital, 2018)

Advantages and Disadvantages of the different surgical approaches for SDR (Steinbok, 2007).

Procedure	Advantages	Disadvantages
Multi-level laminectomy L1-S1	The root level can be easily determined, dorsal root can be usually be separated readily from the ventral root at each level the amount of each dorsal root cut can be easily tailored for the individual clinical situation the spinal cord is not at risk of damage the procedure is readily and safely accomplished with loupes or no magnification	Long surgical incision Extensive muscular dissection the laminae are cut at multiple levels, the ventral roots may be damaged during separation from the dorsal roots significant postoperative pain.
Single or Bi-level laminectomy at the level of the conus	Small surgical incision Small amount of muscle dissection Fewer lamine are cut Less postoperative pain Avoidance of the ventral roots	More technically demanding procedure and  magnification with an operating microscope is required for safety More difficult to determine root levels More difficult to tailor the operation to the individual clinical situation Conus at risk

SDR has been shown to be a safe and effective to reduce spasticity of children in all Gross Motor Function Classification System Levels (GMFCS) with the benefits lasting into adolescence and adulthood (Nordmark et al., 2008; Dudley et al., 2013; Alion et al., 2015).

Associated risks:

SDR is a high risk surgery and the procedure is irreversible. Patients may experience deterioration in walking ability, numbness and bladder dysfunction following the operation and later complications including spinal deformity and hip dislocation (NICE, 2010 and The Robert Jones and Agnes Hunt Orthopaedic Hospital, 2014). Scoliosis is generally associated with the traditional multi-level laminectomy technique which exposes about 3 inches of the lower spine (The Robert Jones and Agnes Hunt Orthopaedic Hospital, 2014). Other suggested adverse events include death, worsening motor function and/or paraplegia, infection of the surgical wound, meningitis, cerebrospinal fluid leakage, constipation, weakness, chronic pain, and late arachnoiditis and/or syringomyelia (NICE, 2010).

Cerebral Palsy

Spasticity

Editing in process.

21/05/18