The control of perineal malignant pain is difficult and challenging for pain physicians. Different modalities have been tried to treat this complex pain syndrome including pharmacotherapy and interventional therapy.

Neuroaxial phenol rhizolysis is simple and cheap option. However; for patients with pelvic or rectal neoplasms and intact bowel and bladder sphincteric functions, there are neurosurgical recomendations of selective sacral nerve roots rhizotomy blockade "as an alternative to chemical saddle rhizotomy".

40 selected patients were randomly allocated into 2 groups "20 patients each"

Group 1 "RF group": in which patients underwent thermal radio Frequency, selective (unilateral S3, bilateral S4 and S5) saddle rhizotomy.

Group 2 "phenol group": in which patients underwent hyperbaric chemical saddle rhizotomy using 6% phenol in glycerin.

Inclusion Criteria:

• Cancer patients with moderate to severe perineal pain (VAS > 40mm over 100 mm scale).
• Intractable pain not responding to adequate tolerated opioid therapy + adjuvant therapy after reasonable period of time for at least 4 weeks (Rad and Kallmes, 2011).
• Limited life expectancy < 12 months (Slatakin etal 2003).
• Patients are continent to urine and stool (no stomas).

Exclusion Criteria:

• Uncorrected coagulopathy.
• Local or systemic sepsis.
• Known allergy to the used medications.
• Distorted local anatomy e.g. by advanced local neoplastic growth rendering the procedure technically difficult or hazardous.
• Sign of increased intracranial tension (Mintzer and Devarajan, 2012).

assessment will be done by junior stuff who is blind to the technique of intervention