Rhizotomy

A selective dorsal rhizotomy (SDR), also known as a rhizotomy, dorsal rhizotomy, or a selective posterior rhizotomy, is a neurosurgical procedure that selectively cut problematic nerve roots of the spinal cord. This procedure has been well-established in the literature as a surgical intervention and is used to relieve negative symptoms of neuromuscular conditions such as spastic diplegia and other forms of spastic cerebral palsy. The specific sensory nerves inducing spasticity are identified using electromyographic (EMG) stimulation and graded on a scale of 1 (mild) to 4 (severe spasticity). Abnormal nerve responses (usually graded a 3 or 4) are isolated and cut, thereby reducing symptoms of spasticity. Spasticity is defined as a velocity-dependent increase in muscle tone in response to a stretch. This upper motor neuron condition results from a lack of descending input from the brain that would normally release the inhibitory neurotransmitter gamma amino butyric acid (GABA), which serves to dampen neuronal excitability in the nervous system. Spasticity is thought to be caused by an excessive increase of excitatory signals from sensory nerves without proper inhibition by GABA. Two common conditions associated with this lack of descending input are cerebral palsy and acquired brain injury. Selective dorsal rhizotomy (SDR), less often referred to as selective posterior rhizotomy (SPR), is the most widely used form of rhizotomy, and is today a primary treatment for spastic diplegia, best done in the youngest years before bone and joint deformities from the pull of spasticity take place. Still, it can be performed safely and effectively on adults as well. SDR is a permanent procedure that addresses the spasticity at its neuromuscular root: i.e., in the central nervous system that contains the misfiring nerves that cause the spasticity of those particular muscles in the first place. After SDR, the person's spasticity is usually eliminated, revealing the "real" strength (or lack thereof) of the muscles underneath.