Chemical neurolysis is a last-line therapeutic option for patients with difficult-to-control visceral pain – most commonly in the course of advanced pancreatic cancer, gastric cancer, colorectal cancer, pelvic cancer and chronic pancreatitis. It involves the permanent (or temporary) interruption of conduction in the nerve plexus responsible for transmitting visceral pain.

Mechanism of Action – How Does Alcohol/Phenol Deactivate Nerves?

Chemical neurolysis uses the neurotoxic properties of chemical agents: ETHYL ALCOHOL (ethanol) at 50–100% concentration or PHENOL at 6–12% concentration (sometimes glycerol). After precise administration under fluoroscopic X-ray (or CT) guidance directly onto the selected nerve plexus, the chemical agent causes:

  • ALCOHOL: precipitates structural proteins of axons and myelin sheaths, causing Wallerian degeneration. Acts intensively but rapidly (seconds-minutes). Produces a strong, predictable effect. May cause transient neuritis – hence the protocol often involves prior local anaesthetic administration
  • PHENOL: has a simultaneous local anaesthetic effect (protective – no painful neuritis) and neurodestructive action. Requires larger volumes and higher concentrations. Better tolerated in patients sensitive to pain
  • Both agents cause irreversible axonal damage (compared to cryolesion – reversible, or PRF – modulatory)
  • Duration of effect: 3–6 months, sometimes longer; the procedure can be repeated if symptoms recur

Celiac Plexus (Coeliac Plexus) – Pain from the Upper Abdomen

The celiac plexus is the largest plexus of the autonomic nervous system in the abdominal cavity, located anterior to the first lumbar vertebra (L1), around the coeliac arterial trunk and the superior mesenteric artery. It consists of sympathetic, parasympathetic and visceral sensory fibres. It receives pain impulses from ALL organs of the upper abdomen:

  • Pancreas (pancreatic cancer, chronic pancreatitis) – the most common indication
  • Liver and bile ducts (liver cancer, cholangiocarcinoma)
  • Stomach (gastric cancer)
  • Spleen
  • Duodenum and upper small intestine
  • Adrenal glands

In 70–80% of patients with advanced pancreatic cancer, pain is the dominant clinical symptom, often resistant to high doses of opioids. Celiac plexus neurolysis provides significant pain reduction in up to 70–80% of patients (Wong 2004, JAMA study), substantial reduction in opioid consumption and improvement in quality of life in the final months of illness.

Splanchnic Nerve Neurolysis – An Alternative

The splanchnic nerves (greater, lesser, least) originate from the thoracic spinal cord (Th5–Th12) and run to the celiac plexus. Neurolysis of these nerves at the Th11 and Th12 level is an alternative route for eliminating visceral pain, particularly effective when classic celiac plexus neurolysis has not worked (e.g. due to altered anatomy from extensive tumour infiltration).

Superior Hypogastric Plexus – Pain from the Lower Abdomen and Pelvis

The superior hypogastric plexus is located anterior to the intervertebral disc at the L5–S1 level, in the retroperitoneal space. It receives impulses from the pelvic organs and lower abdomen. Indications for neurolysis:

  • Prostate cancer with severe pelvic pain (advanced stages)
  • Cancer of the cervix, uterine body, ovaries
  • Bladder cancer
  • Rectal and anal cancer
  • Advanced endometriosis with treatment-resistant pain
  • Chronic pelvic pain syndrome

nferior Hypogastric Plexus / Ganglion Impar (Walter’s Ganglion) – Perineal Pain

The inferior hypogastric plexus lies anterior to the third anterior sacral foramen and can be accessed via this approach. Indications for its deactivation are similar to those for the Ganglion Impar.

Walter’s Ganglion (Ganglion Impar, the unpaired ganglion) is a small, single ganglion located anterior to the coccyx (sacrococcygeal junction). It receives pain impulses from the perineum, anus, distal rectum and lower urinary tract. Indications for neurolysis/PRF:

  • Cancer-related perineal pain (cancer of the anus, lower rectum, perineum)
  • Coccygodynia (chronic coccyx pain)
  • Perineal pain after pelvic radiotherapy
  • Chronic non-specific perineal pain, resistant to other treatments

The procedure is performed under fluoroscopic X-ray guidance, in the prone position, via a short approach through the sacrococcygeal ligament.

Intrathecal (Subarachnoid) Neurolysis

The most advanced neurolysis technique – involves administration of hyperbaric (concentrated) phenol or hypobaric alcohol into the subarachnoid space using a special patient positioning technique to selectively deactivate the pain fibres of specific spinal nerve roots. Used in resistant cancer pain limited to selected dermatomes, e.g. in bone pain from metastases.

Procedure Sequence (using celiac plexus neurolysis as an example)

  • Oncological and pain consultation, assessment of prognosis and general patient condition. Current contrast-enhanced CT of the abdomen.
  • IMPORTANT: Prior to neurolysis, a DIAGNOSTIC celiac plexus block with local anaesthetic (bupivacaine) is usually performed. If the patient experiences significant pain reduction (>50%) – they are a good candidate for neurolysis.
  • Patient in the prone position on the table with fluoroscope. IV access and monitoring (blood pressure, ECG, pulse oximetry).
  • After skin anaesthesia, under fluoroscopic X-ray (or CT) guidance, two 22G needles, 15–20 cm long, are introduced bilaterally via the posterolateral route (at the level of the L1 vertebral body), so that the needle tips are positioned in the vicinity of the celiac plexus (anterior to the spinal column, at the level of the celiac trunk origin).
  • After confirming correct positioning (aspiration test – no blood/CSF), a small volume of iodine contrast is administered – its correct retroperitoneal distribution visible on fluoroscopy confirms the safety of further administration.
  • 10–25 ml of 50–100% ETHANOL (or 6–10% PHENOL in glycerol) is administered from each side.
  • The patient may feel transient warmth, tingling or brief abdominal pain – usually resolving within a few minutes.
  • Remains in the recumbent position for 2 hours after the procedure, monitored for orthostatic hypotension (the most common side effect).
  • Same-day discharge with transport.

Preparation

  • Current contrast-enhanced CT of the abdomen (confirming anatomy, absence of vascular abnormalities)
  • Anaesthesiology consultation – risk assessment, medication review, decision on sedation vs. local anaesthesia only
  • Discontinuation of anticoagulants per ASRA protocol
  • Fasting for 6 hours (water – 2h)
  • Intravenous fluid therapy before/during the procedure (prevents hypotension)
  • Return transport
  • Informed consent – the patient must understand the permanent and irreversible nature of the procedure

Effects

  • First relief: 24–48 hours after the procedure (after the local anaesthetic effect subsides and neurolysis develops)
  • Full effect: 1–2 weeks
  • Duration of effect: 3–6 months (in pancreatic cancer often until the end of the patient’s life)
  • Efficacy in pancreatic cancer pain: 50–80% pain reduction in 70–90% of patients
  • Significant reduction in opioid consumption (by 30–60%)
  • Improvement in quality of life in the final months of illness (Wong 2004 – JAMA study)
  • The procedure can be repeated if symptoms recur (repeat celiac plexus neurolysis provides 50–60% efficacy – McGreevy 2013)

Possible Side Effects

  • Orthostatic hypotension (most common – up to 30–40% of patients) – results from sympathetic denervation of mesenteric vessels. Usually transient, managed with fluid therapy
  • Transient diarrhoea (15–25%) – sympathetic intestinal denervation leads to parasympathetic dominance
  • Transient pain in the procedure area (1–7 days)
  • Minor haematoma at the puncture site
  • Very rarely (<1%): bleeding, infection, paralysis (from alcohol spreading to adjacent motor roots), sexual dysfunction impairment (with hypogastric plexus)
  • Occasionally: earlier than expected pain recurrence

FAQ

Is celiac plexus neurolysis the only option for pancreatic cancer pain?

No – it forms part of a broader cancer pain management strategy that also includes opioids, adjuvant medications (gabapentin, pregabalin, antidepressants), targeted radiotherapy to the celiac plexus (CP-SBRT) and spinal cord stimulation. Neurolysis is the method of choice for patients in whom standard pharmacotherapy does not provide adequate pain control or causes unacceptable side effects.

Is the procedure painful?

The moment of alcohol administration may cause brief (seconds-minutes) sensations of burning or abdominal cramps. We administer local anaesthesia and often sedation, minimising discomfort. After the procedure, patients typically experience significant relief.

How soon after a pancreatic cancer diagnosis should neurolysis be considered?

Current guidelines suggest considering celiac plexus neurolysis EARLY in treatment – ideally when pain begins to require strong opioids, rather than as an absolute last resort. Early neurolysis avoids opioid dose escalation and its side effects (constipation, confusion, respiratory depression).