DREZotomy

Severe spasticity, intractable cancer pain, brachial plexus avulsion…… are some of the diseases that can be treated by this modern surgery……

Overview Of Dorsal Root Entry Zone Rhizotomy

DORSAL ROOT ENTRY ZONE RHIZOTOMY (DREZotomy)

  • Dorsal Root Entry Zone Rhizotomy is useful for the patients with paraplegia and severe pain.
  • In this surgical procedure, lesioning is done at the level of the dorsal horn of the spinal cord where the sensory nerve roots enter. This lesioning alters the spinal reflex arc and thus relieves the spasticity.
  • Following this surgical procedure any chances of returning of motor functions are lost. Therefore, this procedure is advised to those patients who have no chance of improvement in their motor functions.
  • This procedure is only performed one time and the relief from the spasticity is life-long. This is the biggest advantageous point of this procedure.
  • The surgical procedure does not only help in relieving the spasticity but also helps in alleviating the pain.
  • For relief from severe spastic paraplegia, it is advised to resect minimum five roots with sparing of the fourth lumbar root intact, because this spared root usually guarantees about the extensor reflex of the knee which is important for standing and walking. However, during procedure intraoperative neurophysiological monitoring is used to know that by stimulation of which lumbar roots the extension reflex of the knee is affected.
  • Thus, the common practice is to resect the second, third and fifth lumbar roots along with first and second sacral roots.
  • To decrease the chances of sensory deformity, it is advised to preserve at least one rootlet out of five (on average) for each root, from L1 to S1.

The Technique of Microsurgical DREZotomy

Micro-surgical DREZotomy (MDT) – tries to selectively interfere the small nociceptive and the large myotatic fibres (situated laterally, centrally and respectively), while sparing the large lemniscal fibres which are reordered medially. It also enhances the inhibitory mechanisms of Lissauer’s tract and dorsal horn.

MDT is indicated in bedridden paraplegic patients as well as in hemiplegic patients with painful hyper spasticity. It can also be used to treat neurogenic bladder with uninhibited detrusor contractions.

MDT consists of:

  • 3 mm deep microsurgical incision is taken in the dorso-lateral sulcus.
  • The incision is done at an angle of 35 degrees for cervical level and at 45 degrees for lumbo-sacral level.
  • After reaching to DREZ, it is penetrated in its ventrolateral aspect, at the level of the entrance of rootlets which are involved in spasticity.
  • To study the motor responses during procedure neurophysiological monitoring with paired needle electrodes is used.
  • Somatosensory evoked potentials (SSEPs) recording is least important but still useful in testing the function of the spinal cord intraoperatively.

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