171&Sch ch130 Dorsal root entry zone lesion (DREZ)
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Youmans Neurological Surgery
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171&Sch ch130 Dorsal root entry zone lesion (DREZ)
- 1. Dorsal root entry zone lesions Youmans Chapter 171 Diaa Bahgat, Diyendu K. Ray, Kim J. Burchiel Schmidek Chapter 130 Kevin Cahill,Allan J.Belzberg,William S. Anderson
- 2. Termination • Analgesia (pain or pin sensation) • Anesthesia (touch) • Hypesthesia (touch) • Hypalgesia • Hyperesthesia (touch) • Dysesthesia • Paresthesia • Hyperpathia ,
- 3. Pain mechanism • Pain perception – Pain receptor • pain stimuli : chemical(heat, cold,histamine, serotonin etc.), physical(touch) • free nerve ending electrical potential pain impulse – Pain pathway • Epicritic pain, pricking pain, fast pain – Small myelinated or A delta • Protopathic pain, slow pain ,ache – Unmyelinated or C fiber • 1st order neuron : dorsal root ganglion • 2nd order neuron : cell bodies in dorsal horn contralateral spinothalamic tract • 3rd order neuron : thalamus post central gyrus
- 4. Ablation of Dorsal root entry zone(DREZ) • Thermocoagulation at entry zone of the dorsal spinal root • Destructive of 2nd order neuron of nociceptive pain • 1972 France,Lyon by Sindou pain due to pancoast tumour • Cancer-related pain • Refractory pain – brachial plexus avulsion(BPA) – spinal cord injury(SCI) – postamputaion pain – radiation-induced plexopathy(numbness, paresthesia, and dysesthesia, along with swelling and weakness of the arm)
- 5. Anatomy • DREZ : region of the spinal cord that contains the • dorsolateral fasciculus of Lissauer and Rexed laminae I to V • Small rootlet 1 cm before to dorsolateral spinal cord • Small fiber : laterally, nociceptive pain, enter Lissauer’s tract laminae I and II(substantia gelatinosa) of the dorsal horn superficial for surgery • larger fibers : medial somatic receptors
- 6. Anatomy
- 7. Anatomy
- 8. Indication • Pain from neoplasm, trauma, and infection – Pancoast tumour • BPA has been the most widely described application and is associated with the best results – Scar form at dorsal horn and stantia gelatinosa loss of inhibitory of large caliber sensory fiber and to spontaneous activity in nociceptive specific – constant crushing-type sensation – Episodic – pain in the hand or bursts of pain traveling down the arm – resistant to most medical therapies
- 9. Indication • spinal cord or cauda equina injury – Nociceptive • activation of peripheral nociceptors due to ongoing tissue damage • responsive to NSAID • physical therapy. – Neuropathic • 10 – 25 %, immediate or several years • result of an abnormally functioning nervous system : burning character • At level(> 40 yrs)and below level( < 40 Yrs)
- 10. Indication • postherpetic neuralgia – More common in thoracic level • occipital neuralgia • phantom limb pain – Not first line,option for fail medical or surgical method – sensation of shortening or lengthening of the limb – Numbness,Itchiness,temperature differences,cramping • radiation-induced plexopathy • decreased muscle tone and abolished stretch reflex
- 11. Surgical technique • Preoperative consideration – Pt with fail medication • selectively destruct – excitatory pain fibers, – unmyelinated and small myelinated pain fibers in the ventrolateral DREZ and the medial portions of Lissauer’s tract • Pre-op : intravenous corticosteroid for acute SCI • Prone position : expose to C3- T1 lamina, pin fixation • Cervical hemilaminectomy : unilateral procedures • Complete laminectomy : bilateral procedures
- 12. Surgical technique • Open dura then nerve root expose • Root identification : bipolar stimulation, with a 2.5-Hz frequency and an increasing voltage from 1 to 6 V. • Incision depth 2 mm at the junction of the rootlets and the dorsolateral funiculus, open both for comparison • Stimulation dorsal column with recording of a somatosensory evoked potential to identify midline : dorsal column fiber
- 13. Surgical technique • Microcoagulation : Radiofr35-degree angle,depth of 3 mm ,Staccato fashion • High frequency-generated heat – cordotomy needle placed in the posterolateral sulcus – slight contraction of the tissue is evident (10-20 seconds) or heat the electrode to 75°C for 15 seconds – Multiple lesions are placed at 1- to 2-mm intervals covering the area of avulsion – Continue lesion fron avulsion to partial injured lesion : maximal result • Carbon dioxide laser, Ultrasound-mediated DREZ ablation , Nd:YAG(neodymium:yttrium-aluminium-garnet)
- 14. Surgical technique • Bipolar – Power 20-25 – DREZotomy • Landmark – Line last intact dorsal root to visible root intact distal – Pit left by avulsion root – Small vein run laterally to DREZ • Avoid injury to dorsal column medially and corticospinal tract laterally
- 18. Outcome • BPA,SCI,postherpetic neuralgia, arachnoiditis, pain secondary to spinal cysts, and cauda equina lesions • No RCT comprare to other therapy • Relieve pain at least 50% • SCI : 54%, BPA : 84% • Sindou and coauthor, 42 – 66% good excellent outcome – 71% improve in daily activity – Mean F/U 6 Yrs • Better result in Pt who underwent surgery more than 1 Yr
- 19. Outcome • Long term follow up – John Hopkin Hospital 28 mo,relieve 85% – 87% of patients, with an average follow-up of 47.5 months – 94.6% (55) excellent pain relief on hospital discharge, with 65.9% showing persistent relief on long-term follow-up. • Pain relief greater in paroxysmal pain alone compared to that in patients with continuous pain • SCI – Incomplete cord – 3% : 3 months, 68% : 1 year
- 20. Outcome • postamputation phantom pain – good long-term relief in 36% – Some report, not respond • postherpetic neuralgia – 17 / 10 – Superficail burning pain – Only 20 % persistent pain • radiation-induced plexopathy – 8/10,respond
- 21. Complication • general complications following spinal surgery – CSF leak 1/55 – Meningitis 2/55 – Post-amputaiotn pain : epidural hematoma 1/28 • neurologic complications – Decreased sensation(hypoesthesia) sensation ipsilateral to the DREZ ablation – Dysesthesias(unusual and frightening physical disorder) ipsilateral to the DREZ ablation – Ataxia, motor weakness – sphincter dysfunction
Editor's Notes
- Pancoast syndrome (Pancoast’s syndrome) is characterized by a malignant neoplasm of the superior sulcus of the lung (lung cancer) with destructive lesions of the thoracic inlet and involvement of the brachial plexus and cervical sympathetic nerves (stellate ganglion)