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7 Articles in Volume 4, Issue #4
Blockades for Sympathetically Maintained Pain (SMP)
Fibromyalgia & Myofascial Pain Syndromes
Fifteen Minute Headache Evaluation
From Research To Practical Application: Long Term Testosterone Treatment
Thermography in Pain Management
Treatment of Acute Pain in the Orthopedic Patient
Women and Chronic Pain

Blockades for Sympathetically Maintained Pain (SMP)

A state-of-the-art survey of sympathetic blockades for SMP syndromes presenting in various parts of the body.

The sympathetic nervous system has been implicated in numerous pain syndromes while interruption of the sympathetic flow has been proven to relieve certain pain syndromes. Such pain syndromes are referred to as Sympathetically Maintained Pain Syndromes (SMP). To optimize the outcome following sympathetic blockade, accurate diagnosis of sympathetically maintained pain (SMP) should be made.1,2

Sympathetically maintained pain presents clinically with neuropathic pain picture i.e. burning, Stabbing, shooting in nature with allodynia. Classically these SMP, like other neuropathic pain syndromes, respond to Tricyclic Antidepressants (TCA) and anticonvulsant drugs (AC). Laboratory tests can also confirm some degree of neuropathic pain component which can probably be sympathetically maintained pain (triple phase bone scan).1

There is no gold standard criteria to determine if the neuropathic pain syndrome is SMP or not; some have suggested that two or more of the following four test to be positive. The four tests include:

  1. good pain relief following sympathetic blockade which is directly related to the duration of the local anesthetic agent used, preferably a local anesthetic agent should be used versus a placebo;
  2. response to intravenous phentolamine infusion which produces system sympathetic blockade;
  3. aggravation of the pain following infusion of norepinephrine;
  4. the relief of the pain with infusion of clonidine or application of clonidine patch.

The classical targets for sympathetic blockade are the sphenopalatine ganglia (for vascular headache, and cranial neuralgias), stellate (cervicothoracic) sympathetic ganglia (for SMP and vascular disorders, in the upper extremities), celiac/splanchnic plexus (abdominal SMP and visceral malignant and non-malignant pain), lumbar sympathetic ganglia (lower extremity SMP and related pain syndromes), superior hypogastric (for pelvic pain and pelvic visceral malignancies), and ganglia impar (peri-anal and rectal pain). See Table 1 for a summary of the blockades discussed in subsequent sections.1-9

In addition to the pharmacological and non pharmacological therapies, local anesthetic and neurolytic blocks to the sympathetic axis are effective for controlling pain. During the performance of sympathetic blockade, it is recommended that an IV access be maintained should complication occur as well as monitors —including temperature — for the extremities to indicate successful sympathetic blockade to that extremity.1-3

Blockades for Sympathetically Maintained Pain (SMP) Syndromes

 

Sphenopalatine Ganglia Block (SPG)

Indications: 1. Vascular Headache. 2. Facial Neuralgia. 3. Spheno-palatine neuralgia.
Potential Complications: Mechanical — traumatic injury to the maxillary nerve, vascular trauma / hematoma, epistaxis and pain at the site of the injection. Pharmacological — intravascular injection, damage to the maxillary nerve by the neurolytic agent and seizure from the local anesthetic agent

 

Cervicothoracic / Stellate Ganglion Block

Indications: 1. Head and neck painful conditions if SMP (herpes Zoster pain and post-herpetic neuralgia). 2. CRPS type I (RSD) and II (Causalgia) and other sympathetically maintained pain syndromes to the upper extremities and to the anterior chest wall. 3. Vascular insufficiency /vascular disorders including Raynaud’s disease, and other vascular conditions to the upper extremities, head and neck, including some vascular type of headaches (migraine, cluster headaches).
Contraindications: Contralateral phenic nerve palsy, blood dyscrasia/coagulopathy, local sepsis and patient refusal.
Potential Complications: Mechanical — pain from the injection, hematoma, pneumothorax, pneumomediastinum, injury to the esophagus, brachial plexus and vasovagal attacks. Pharmacological — Horner’s syndrome, spinal analgesia, brachial plexus and phrenic nerve block leading to difficulty in breathing, recurrent laryngeal nerve block leading to hoarseness of voice, and seizure because of intravascular injection.

 

Celiac/ Splanchnic Nerve Plexus Block

Indications:1. Acute/chronic pancreatitis and hepatobiliary disorder including biliary sphincteric disorder (biliary dyskinisia). 2. Abdominal visceral pain syndrome including abdominal malignances. 3. Abdominal angina. 4. To differentiate visceral pain from somatic pain syndrome of the abdominal cavity (somatic pain will nor respond to celiac plexus block).
Potential Complications: Mechanical — injury to the blood, kidney and ureter lung and pleura (pneumothorax, hemopneumothorax, pleurisy), paraplegia because of intravascular/intrathecal injection or because of trauma to the blood supply to the spinal cord (artery of Adamkeiwicz). Pharmacological — hypotention, and diarrhea because of sympathetic blockade, intravascular injection (seizure), alcohol neurolytic block can cause alcohol withdrawal in people with disulfiram therapy for alcohol abuse. Phenol should be avoided in patients who have vascular prosthesis, as it can attack the prosthesis. IV access should be maintained and pre-load of fluid is also advisable to reduce the severity of hypotention.

 

Lumbar Sympathetic Block

Indications: 1. CRPS type I and II (SMP). 2. Vascular insufficiency /disorder to the lower extremity. 3. Neuropathic pain i.e. post-herpetic neuralgia. to the lower extremities. 4. Visceral pain (renal colic)
Potential Complications: Mechanical — Infection,trauma to the lumbar nerve and disc, intravascular, intrathecal and epidural injection. Kidney trauma (hematuria). Pharmacological — Intravascular or intrathecal injection of local anesthetic agent or neurolytic agent, hypotension, paraplegia and, in case of neurolytic block, genitofemoral neuralgia.

 

Superior Hypogastric Plexus Block

Indications: Treatment of pelvic pain including malignancy, endometriosis or pelvic inflammatory diseases/adhesions.

 

Ganglion Impar (Ganglion of Walther) Block

Indications: Peri-anal pain which is sympathetically maintained or visceral pain.
Potential Complications: Caudal/epidural spread, injury to the rectum or to the periosteum and infection.

Sphenopalatine Ganglia Block (SPG)

SPG is located in the pterygopalatine fossa (the sphenopalatine fossa) which is located posterior to the middle nasal conchae and anterior to the pterygoid canal. It lies in close proximity to the maxillary nerve. The sympathetic nerve passes through this ganglia to supply the sensory, vasomotor and secretary fibers to the sphenopalatine, lacrimal and nasal glands, and also to some of the sympathetic fibers along the cranial blood vessels.1-4 Indications for this block include vascular-related headache (migraine, cluster headache), fascial neuralgia and spheno-palatine neuralgia (i.e following sinus or teeth surgeries).1-5

The simplest technique for SPG Block is using two soft cotton-tip applicators, with cocaine or viscous lidocaine, and then advanced through the nares, along the middle turbinate posteriorly. A second applicator is then applied superior and posterior to the first one, and they should both be left in position for 30 minutes.1,4

Fluoroscopic guided block can be used for both temporary and permanent block to the SPG (i.e. neurolytic lesion or radiofrequency ablation). Using fluoroscopy, the needle is inserted in between the mandibular rami and under the Zygoma, aiming to the sphenopalatine fossa. Paresthesia to the maxillary nerve may occur and some local anesthetic agent may reduce the pain.

On A-P view, the needle tip should lie just adjacent to the lateral nasal cavity wall, 1/2 to 1 ml of contrast dye or electrical stimulation using 2 hertz and 100 hertz through the RF needle can confirm the correct position of the needle tip. Stimulation should produce a tingling sensation into the nasal area and nasal cavity. Following that, 1 ml of local anesthetic agent or neurolytic agent can be applied. Alternatively, radiofrequency ablation can be performed.1,3,4

Complications may include mechanical traumatic injury to the maxillary nerve, vascular trauma/hematoma, epistaxis and pain at the site of the injection as well as potential complications from the intravascular injection, damage to the maxillary nerve by the neurolytic agent, and seizure from the local anesthetic agent.

Cervicothoracic/Stellate Ganglion Block

Sympathetic flow to the head and neck and to the upper extremities is derived from the upper five to seven thoracic spinal segments. Cell bodies are located in the gray matter of the dorsolateral spinal cord material. They exit with the anterior primary rami as white rami communicante. The fiber ascends along the anterior lateral surface of the spinal column, to the three cervical sympathetic ganglia (superior, middle and inferior cervical sympathetic ganglia).1,3-5

In 80% of patients with the inferior cervical and the first thoracic sympathetic ganglia fused together to form the Stellate ganglia. This is why it is more appropriate to describe the cervicothoracic sympathetic blockade, rather than using the term sympathetic stellate ganglia block. The Stellate ganglia lies in front of the neck of the first rib by the dome of the pleura. It supplies the head and neck, and most of the upper limb sympathetic flow with the notable exception of the nerve of Kuntz which arises from T2 spinal segment and bypasses the cervicothoracic/stellate ganglia and continues to the upper extremity. This may explain why stellate ganglia block or upper cervical thoracic ganglia block sometimes may not provide total sympathectomy to the upper extremity.

This block is indicated for the following conditions:

  1. Head and neck painful conditions if SMP (herpes Zoster pain and post-herpetic neuralgia).
  2. CRPS type I (RSD) and II (Causalgia) and other sympathetically maintained pain syndromes to the upper extremities and to the anterior chest wall.
  3. Vascular insufficiency/vascular disorders including Raynaud’s disease, and other vascular conditions to the upper extremities, head and neck, including some vascular type of headaches (migraine, cluster headaches).

Two classical techniques use either the C6 or the C7 vertebra as a landmark. After identification of the level, either under fluoroscopy or by palpating the C6 transverse process (the Chassaignac’s process), it can be used as a landmark. At the junction of the body and the transverse process of either C6 or C7, the periosteum can be contacted using a 27-gauge short beveled needle. The carotid artery can be retracted laterally with the sternomastoid to avoid puncture. Once the periosteum is contacted, the needle is withdrawn a few millimeters.

After negative aspiration for both blood and CSF, 1 ml of dye can be injected. If there is no intravascular or intrathecal spread but good spread along the sympathetic ganglia, it is followed by the injection of .5 ml of local anesthetic and a wait period of two to three minutes to exclude any signs of CNS toxicity (intravascular injection) or spinal analgesia (intrathecal injection). Finally, 2 - 10 ml of local anesthetic is injected. Sympathetic blockade to the head and neck can be confirmed by the development of Horner’s syndrome.1,2,4,5

Confirmation of sympathetic blockade to the upper extremity can be done by measuring the skin temperature which should increase by at least 2 to 3 degrees centigrade. A modified posterior and anterior approach to the upper thoracic sympathetic ganglion can also be used for SMP to the upper extremities to avoid Horner’s Syndrome.2,3

Complications may include pain from the injection, hematoma, pneumothorax, pneumomediastinum, injury to the esophagus, brachial plexus and vasovagal attacks. Pharmacological complications may include Horner’s syndrome, spinal analgesia, brachial plexus and phrenic nerve block leading to difficulty in breathing, recurrent laryngeal nerve block leading to hoarseness of voice (this is why bilateral stellate ganglia block/cervicothoracic ganglia block should not be attempted bilaterally) and seizure because of intravascular injection.2,3-5,7

Contraindications include contralateral phenic nerve palsy, blood dyscrasia/coagulopathy, local sepsis and patient refusal.1,4

Celiac/Splanchnic Nerve Plexus Block

Sympathetic supply to the abdominal viscera arises in the anterior lateral horn of the spinal cord. Pre-ganglionic fibers from the T5- T10 spinal segment give rise to the lesser splanchnic (T11-12), the greater splanchnic (T5-10) and the least splanchnic (T12). These nerves hug the thoracic vertebral then pass to the Celiac plexus.Celiac ganglia is a mesh-like structure which lies in front of the great abdominal vessel. It measures about 1 to 4.5 cm in diameter at the level of the first lumbar vertebra. From there, the post-ganglionic fibers supply the abdominal viscera.1-4

Interruption of the sympathetic flow has been proven to relieve certain pain syndromes. Such pain syndromes are referred to as Sympathetically Maintained Pain Syndromes (SMP).

Multiple approaches have been used to block the celiac plexus, including the anterior, posterior approaches and open techniques. The classical technique will be described here which is the posterior approach. The posterior approach can also be retrocrural or transcrural. An alternative approach could also be transaortic, where the needle will lie in front of the aorta (Celiac ganglion block), the transcrural is referred to as celiac plexus block while the retrocrural is referred to splanchnic nerve block.

Although all provide effective sympathetic blockade, the splanchnic block is reserved for those patients who have abdominal pathology such as widespread metastasis of tumor, which makes a transaortic approach difficult, or if there is a vascular anomaly (i.e. aortic aneurysm) which prohibits it.1,3-5

The posterior approach is done with the patient in the prone position. This is either done using fluoroscopy or CT scan. The difference between the retrocrural and the transcrural is the final position of the needle tip. If it is at the level of T12 vertebra in the lower third anterior lateral area, then it is referred to as transcrural. If at the middle to upper third of the L1 vertebra, then it is a retrocrural approach. The needle is usually inserted at the edge of a triangle which is formed from the T12 rib, L1 transverse process and the tip of the T12 spinous process. The needle is then directed so that the final position will be either in front of the T12 or the L1 vertebra, depending whether this is transcrural or retrocrural approach. Bilateral needles should be inserted. The position is confirmed by both AP and lateral view and by the injection of dye. Following confirmation of the spread of dye, either local anesthetic agent is injected (8-15 ml on each side).1,3,4

Alcohol or phenol may be used for a more permanent blockade. Before lytic block is performed, local anesthetic agent should be injected initially to be sure that there is no intravascular or intrathecal epidural spread as confirmed by the development of spinal analgesia, then the alcohol or phenol should be injected.1,4

Indications for Celiac/ Splanchnic Nerve Plexus Block include:1,3,4,5,9

  1. Acute/chronic pancreatitis and hepatobiliary disorder including biliary sphincteric disorder (biliary dyskinisia).
  2. Abdominal visceral pain syndrome including abdominal malignances.
  3. Abdominal angina.
  4. To differentiate visceral pain from somatic pain syndrome of the abdominal cavity (somatic pain will nor respond to celiac plexus block).

Complications may include injury to the blood, kidney and ureter lung and pleura (pneumothorax, hemopneumothorax, pleurisy), paraplegia because of intravascular/intrathecal injection or because of trauma to the blood supply to the spinal cord (artery of Adamkeiwicz). Pharmacological complications may include hypotention, diarrhea, intravascular injection (seizure). Note that alcohol neurolytic block can cause alcohol withdrawal in people having disulfiram therapy for alcohol abuse. Phenol should be avoided in patients who have vascular prosthesis, as it can attack the prosthesis. IV access should be maintained and pre-load of fluid is also advisable to reduce the severity of hypotention.1,3,4

Lumbar Sympathetic Block

Pre-ganglionic flow to the lower extremities arises from the dorsolateral part of the spinal cord (lower thoracic and upper two lumbar segments). They synapse into the lumbar sympathetic ganglia which is located in the anterior lateral surface of the L2 to the L4 vertebra, anterior to the psoas muscle. However, there is some individual variation in the position.4 Most post-ganglionic sympathetic fibers accompany nerve roots to the lower extremity.1,3-5

Using the lateral approach technique, in the prone position, using a 5-inch spinal needle, under fluoroscopy, by avoiding the transverse process of L2 or L4, the needle is inserted in such way that it will aim so that the final tip of the needle will lie in front of and just lateral to the L2 vertebra (in the mid facetal line) or at the superior third of the L3 vertebra where in most individuals, the sympathetic ganglia is located.4 Injection of dye should confirm the spread in front of and lateral to the vertebral body, both on A-P and lateral view. To confirm sympathetic blockade, again, the temperature of the lower extremity should increase by at least 3 degrees centigrade, with 3 to 5 ml of local anesthetic agent. A small amount of local anesthetic agent is preferable to avoid spread to the somatic nerve thus confusing the outcome of the block (somatic vs SMP).1,3,4

Indications for the Lumbar Sympathetic Block include:1,3-5

  1. CRPS type I and II (SMP).
  2. Vascular insufficiency/disorder to the lower extremity.
  3. Neuropathic pain, i.e. post-herpetic neuralgia, to the lower extremities.
  4. Visceral pain (renal colic).

Complications may include infection, trauma to the lumbar nerve and disc, intravascular, intrathecal, epidural injection, and kidney trauma (hematuria). Pharmacological complications may include intravascular or intrathecal injection of local anesthetic agent or neurolytic agent, hypotension, paraplegia and in case of neurolytic block, and genitofemoral neuralgia.1,4,5

Lumber symaptolysis can be performed either thermal lesion (radiofrequency ablation; RFA), lytic (phenol or Alcohol) or a combination of both to use less neurolytic solution and avoid spill to somatic nerves.1,3,4

Superior Hypogastric Plexus Block

The plexus is located retroperitoneally in the lower third of the fifth lumbar vertebral body and the upper third of sacrum in close proximity to the bifurcation of the common iliac vessel. It receives supply from the lumbar aortic and celiac sympathetic plexus. There are also some parasympathetic fibers from the ventral root of S2 to S4. The superior hypogastric plexus supplies the genital organs and also the sigmoid colon and the rectum. It also communicates with the inferior hypogastric plexus which is located parallel to the pelvic floor. It is not feasible to block the inferior hypogastric plexus.1,3,4,10

Superior hypogastric plexus block is indicated for the treatment of pelvic pain including malignancy, endometriosis or pelvic inflammatory diseases/adhesions.3,4

With the patient in the prone position, with a pillow to flatten the lumbar lordosis, the x-ray beam is turned to 45 degrees posterolateral view at the level of the L5 vertebra. Using the cephalocaudal view to avoid the iliac crest and identify the anterior lateral part of the L5 vertebra.3,4

Using the gun barrel technique, a needle is inserted in such way that the tip will lie in front of the vertebral body of L5. If the transverse process of L4 or L5 is encountered, sometimes bending the needle tip by 50 degrees can be used to bypass. The position is also confirmed by A-P and lateral view, and also by injection of dye. This followed by injecting 3-10 ml of local anesthetic or neurolytic solution on each side.1,3,10

Ganglion Impar Block (Ganglion of Walther)

This is a solitary retroperitoneal structure which is located at the level of the sacrococcygeal junction and it marks the termination of the paravertebral sympathetic chain. Ganglion Impar (Ganglion of Walther) Block is indicated for peri-anal pain which is sympathetically maintained or for visceral pain.1,3,4,11

Of two possible techniques, the easiest is the trans-sacrococcygeal ligament technique, where a needle is inserted through the ligament until it lies just a few millimeters in front of the curvature of the sacrum. This is confirmed by the injection of dye, followed by the injection of 2 to 4 cc of local anesthetic agent or neurolytic agent.

An alternative technique is to insert a needle between the coccygeal and the anal region, through the anococcygeal ligament, and then direct the curvature towards the coccyx until the needle lies anterior to the surface of the bone. Injection of dye confirmation should resemble an apostrophe.1,3,4

Potential complications include caudal/ epidural spread, injury to the rectum or to the periosteum and infection.1,4,11

Cautions

Following sympathetic blockade, especially following neurolytic agent (and also, sometimes, after radiofrequency ablation or surgical symapthectomy), the original pain may reappear.8

New neurological deficit or pain syndrome may also appear. This can be explained by reorganization, resprouting of the sympathic nerves with plasticity of the central and the peripheral nervous system. An alternative explanation is that during injection of lytic agent, some of the somatic nerves nearby could have been injured, and thus producing a new neuropathic syndrome.2,8

Post-sympathectomy syndrome is more common following sympathectomy for neuropathic pain, rather than following hyperhydrosis. Although, even sympathectomy for hyperhydrosis can be followed by neuropathic pain and possibly an increase of the hyperhydrosis as well. The best way to avoid these complications is to use a smaller volume of neurolytic agent, or more localized radiofrequency ablation or surgical lesion.2,8

Last updated on: January 6, 2012
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