Dorsal root ganglion stimulation

Neuromodulation of distal targets such as dorsal root ganglion may permit greater anatomic specificity of the therapy, whereas subthreshold stimulation with high-frequency or burst energy delivery may eliminate noxious and off-target paresthesiae. Such new technologies should be subject to rigorous evaluation as their mechanisms of action and long-term outcomes remain hitherto undefined 1).

Indications

Case series

Piedade et al., from University Hospital of Düsseldorf, reported a consecutive series of 20 patients treated with DRG stimulation in the upper thoracic and cervical region. All patients suffered from chronic neuropathic pain unresponsive to best medical treatment. Main pain etiologies were traumaspine surgerypostherpetic neuralgia, and peripheral nerve surgery. All patients were trialed with externalized electrodes prior to permanent pulse generator implantation. Routine clinical follow-up was performed during reprogramming sessions.

Out of all 20 patients trialed, 18 were successfully trialed and implanted with a permanent stimulation system. The average pain relief after three months compared to the baseline was of 60.9% (mean VAS 8.5 to VAS 3.2). 77.8% of the patients reported a pain relief of at least 50% after three months. One patient developed a transient paresis of the arm caused by the procedure. She completely recovered within three months.

Cervical and upper thoracic DRG stimulation resulted in good overall response rates to trialing and similar pain relief when compared to DRG stimulation for groin and lower limb pain. A modified surgical approach has to be used when compared with lumbar DRG electrode placement. Surgery itself in this region is more complication prone and challenging 2).


Morgalla et al., prospectively enrolled 12 adult patients with unilateral localized neuropathic pain in the lower limbs or inguinal region and followed them up for six months Laser evoked potentials (LEP) were assessed at baseline, after one month of DRGS, and after six months of DRGS. Clinical assessment included the Numerical Rating Scale (NRS), Brief Pain Inventory (BPI), SF-36, and Beck Depression Inventory (BDI). For each patient, LEP amplitudes and latencies of the N2 and P2 components on the deafferented side were measured and compared to those of the healthy side and correlated with pain intensity, as measured with the NRS.

At the one- and six-month follow-ups, N2-P2 amplitudes were significantly greater and NRS scores were significantly lower compared with baseline (all p’s < 0.01). There was a negative correlation between LEP amplitudes and NRS scores (rs = -0.31, p < 0.10).

DRGS is able to restore LEPs to normal values in patients with localized neuropathic pain, and LEP alterations are correlated with clinical response in terms of pain intensity 3).

Case reports

van Velsen et al. used a single-incision approach to tunnel and implant the leads and pulse generator for DRG stimulation treatment in a patient suffering from intractable foot pain. At long-term follow-up, the patient experienced a decrease in pain intensity and improvement in function, without any complications. A single-incision implantation technique for DRG stimulator implantation may simplify implantation and decrease the risk of complications 4).

References

1)

Shamji MF, De Vos C, Sharan A. The Advancing Role of Neuromodulation for the Management of Chronic Treatment-Refractory Pain. Neurosurgery. 2017 Mar 1;80(3S):S108-S113. doi: 10.1093/neuros/nyw047. PubMed PMID: 28350939.
2)

Piedade GS, Vesper J, Chatzikalfas A, Slotty PJ. Cervical and High-Thoracic Dorsal Root Ganglion Stimulation in Chronic Neuropathic Pain. Neuromodulation. 2019 Jan 8. doi: 10.1111/ner.12916. [Epub ahead of print] PubMed PMID: 30620789.
3)

Morgalla MH, de Barros Filho MF, Chander BS, Soekadar SR, Tatagiba M, Lepski G. Neurophysiological Effects of Dorsal Root Ganglion Stimulation (DRGS) in Pain Processing at the Cortical Level. Neuromodulation. 2018 Dec 18. doi: 10.1111/ner.12900. [Epub ahead of print] PubMed PMID: 30561852.
4)

van Velsen V, van Helmond N, Levine ME, Chapman KB. Single-Incision Approach to Implantation of the Pulse Generator and Leads for Dorsal Root Ganglion Stimulation: A Case Report. A A Case Rep. 2017 Aug 14. doi: 10.1213/XAA.0000000000000625. [Epub ahead of print] PubMed PMID: 28816708.

Selective dorsal rhizotomy for spastic diplegia

Selective dorsal rhizotomy (SDR) is often recommended for children with spastic paraparesis and cerebral palsy. SDR reduces spasticity in the lower extremities for these children with spastic paraplegia. However, SDR is infrequently recommended for adults with spasticity. Spastic diplegia in adult patients can be due to stroke, brain or spinal cord injury from trauma, infection, toxic-metabolic disorders, and other causes. Although rarely considered, SDR is an option for adult patients with spastic diplegia as well.

Long-term outcomes of selective dorsal rhizotomy have been promising among the Archer et al., institutional series of patients.

They demonstrated the use of L1-S1 osteoplastic laminoplasty and L1-S1 selective dorsal rhizotomy in a 5-year-old male patient with cerebral palsy and spastic lower extremity diplegia. Favorable selection criteria for this case included disabling lower extremity diplegia, young age, good core strength, no cognitive delay, and strong rehabilitation potential. The patient’s preoperative functional status was noncommunity ambulator (Gross Motor Function Classification System Level III) with walker use and good dynamic balance. Prior to the procedure, he demonstrated an overall decreased muscle strength in bilateral lower extremities with bilateral hamstring spasticity (Modified Ashworth Scale 3) and bilateral heel cord spasticity (Ashworth 4). Rhizotomy was performed with identification and selective sectioning of dorsal nerve roots with abnormal stimulation patterns. Fibers with unsustained discharge of appropriate muscles were identified and spared. No intraoperative or postoperative complications were encountered. The patient had minimal back pain and surgical morbidity postoperatively. Following the procedure and highly structured inpatient and outpatient rehabilitation therapies, the patient exhibited significant improvement in gait velocity (84%) and gait cadence (66%) at 5 months. Additionally, the patient demonstrated greater independence of activities of daily living and improvements in mobility by Pediatric Evaluation Disability Index.Patient consent was obtained from the parent 1).


In a longitudinal study 19 ambulant patients with spastic diplegia due to cerebral palsy (CP) or other causes (mean age at Selective dorsal rhizotomy: 6.6 ± 1.6 years )were assessed four times: pre-Selective dorsal rhizotomy (SDR), 2 years post- SDR, 5 years post-SDR and at least 10 years post-SDR. From 2D video recordings, Edinburgh Visual Gait Score and lower limb joint kinematic parameters were calculated.

Data show that the improvement in the gait pattern obtained short-term after SDR continues during into adolescence and adulthood. Ten years after SDR all patients improved compared to baseline. Considering the lower limb joint kinematics, most notable improvements were found at knee and ankle joints. Compared to the evaluation before SDR, the range of motion of the knee increased: the knee was more extended at initial contact and knee flexion in midswing improved. Excessive ankle plantar flexion was reduced during the entire gait cycle. Only minor changes were found at hip and pelvis. Eight patients underwent additional orthopaedic surgery in the years after SDR, and the present findings should be considered as a combination of SDR, development and additional treatment.

Romei et al., demonstrate lasting improvement of gait quality in ambulant patients with spastic diplegia who underwent SDR during childhood when they become adolescents and young adults 2).


Eppinger et al., describe a patient who underwent a SDR with a successful postoperative outcome. This man suffered a hypertensive and hemorrhagic stroke secondary to intravenous drug abuse at age 46. A SDR was performed after two failed intrathecal baclofen pump placements due to recurrent infections, likely resulting from his immunocompromised status. The patient underwent lumbar laminectomies and dorsal rhizotomies at levels L1-S1 bilaterally. Postoperatively, the patient’s spasticity was significantly reduced. His Ashworth spasticity score decreased from 4/5 to 1/5, and the reduction in tone has been durable over 3 years 3).

References

1)

Archer J, Yaacoub AP, Angulo-Parker F, Fritsch G, Riner S, Coon A, Johnson SK, Delima S, Jea A, Raskin JS. Pre- and Postoperative Gait Analysis and Video for Selective Dorsal Rhizotomy in Spastic Diplegia: 2-Dimensional Operative Video. Oper Neurosurg (Hagerstown). 2018 Dec 27. doi: 10.1093/ons/opy392. [Epub ahead of print] PubMed PMID: 30590806.
2)

Romei M, Oudenhoven LM, van Schie PEM, van Ouwerkerk WJR, van der Krogt MM, Buizer AI. Evolution of gait in adolescents and young adults with spastic diplegia after selective dorsal rhizotomy in childhood: A 10 year follow-up study. Gait Posture. 2018 Jun 4;64:108-113. doi: 10.1016/j.gaitpost.2018.06.002. [Epub ahead of print] PubMed PMID: 29894977.
3)

Eppinger MA, Berman CM, Mazzola CA. Selective dorsal rhizotomy for spastic diplegia secondary to stroke in an adult patient. Surg Neurol Int. 2015 Jun 25;6:111. doi: 10.4103/2152-7806.159382. eCollection 2015. PubMed PMID: 26167363; PubMed Central PMCID: PMC4496840.
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