I really like this case! This is because it explores the outcome of 2 different nerve blocks done on a young cadet (‘Sue’) with complex regional pain syndrome (CRPS) in her lower right leg.
Sue’s 1st nerve block via lateral sciatic catheter resulted in improved but incomplete pain relief. This 1st nerve block had inadvertently missed a certain branch of the sciatic nerve (more later).
As such, a 2nd (i.e. replacement) nerve block via posterior sciatic catheter was required.
Fortunately for Sue, ALL of her pain due to CRPS was finally eliminated once her replacement continuous sciatic catheter was correctly placed.
PRELIMINARY DETAILS
Sue, a young 17-year old female US Military Academy cadet, had a right ankle sprain due to an inversion injury during training. This sprain led to severe pain that radiated upward from her ankle. Sue’s ankle was swollen and the lateral part* of her lower leg and foot was numb. Her foot’s range of motion was very limited.
Within only 1 week, Sue’s orthopaedic surgeon diagnosed early CRPS after confirming severe pain and allodynia as well as vasomotor dysfunction. After 2 weeks of unsuccessful pain medicine treatment, Sue was transferred to Walter Reed Army Medical Center (WRAMC).
By now, Sue’s right foot was red, warm and swollen while her lower right leg displayed colour changes. Her lower leg, particularly the lateral side, and the top of her foot were sensitive to light touch. She had allodynia in the L5 and S1 dermatomes.
Distribution of dermatomes including L5 and S1 dermatomes (Hancock, 2011)
After a failed lumbar sympathetic block that did nothing for her pain, Sue received a ketamine infusion (that was titrated up to the maximum dose the following day).
1st CONTINUOUS SCIATIC NERVE BLOCK VIA LATERAL SCIATIC CATHETER
When Sue was admitted to the Surgical Intensive Care Unit (ICU) for a continuous lateral sciatic catheter placement, her pain levels were 8 out of 10.
Once Sue’s sciatic nerve was located in the popliteal fossa (i.e. knee pit),* and after this nerve’s division into its tibial and common peroneal nerve branches was identified,* the continuous nerve block catheter was placed proximal* to this nerve’s division. The correct placement of this catheter was necessary to achieve a continuous lateral sciatic nerve block.
The needle was then placed next to the sciatic nerve and a single dose of 20 mL 1.5% Mepivacaine with Epinephrine was injected into the nerve sheath.
Thereafter, a continuous infusion of 0.2% Ropivacaine was commenced (10 mL per hour). Sue was also given the option of adding a patient-controlled bolus dose of 3 mL every 20 minutes.
Sue was unable to move her foot up and down shortly after the Ropivacaine infusion started.
Guess what happened next??
Within only 15 minutes, Sue’s pain levels dropped from 8 to 1 (out of 10)! Wow!!
The Ropivacaine and Ketamine infusions continued throughout the night.
The next day, Sue continued to enjoy excellent pain relief in most of her CRPS-affected lower leg, with one notable exception:
There was burning pain and allodynia on the lateral part of her lower leg, just beneath her knee.
The pain in this particular dermatome can not be blocked by the 1st block called a lateral sciatic nerve block. Instead, a different kind of sciatic nerve block was needed.
As such, the Ropivacaine infusion was stopped for 8 hours (during which time Sue’s pain levels rose to 5/10). During this time, a ‘new and improved’ continuous posterior sciatic catheter was placed. This 2nd catheter was precisely located to also target the cutaneous branch of the sciatic nerve (that had inadvertently been overlooked by the 1st catheter).
2nd CONTINUOUS SCIATIC NERVE BLOCK VIA POSTERIOR SCIATIC CATHETER
Guess what happened after the first catheter was replaced and bolus of 30 mL of 0.5% Ropivacaine was released??
Sue finally had nil pain! Nada! Zilch! Zero! Even the lateral part of her lower leg was finally pain free! OMG!
The next morning, Sue was also able to move her foot without pain.
While her Ketamine and Ropivacaine infusions continued for another 3 days, Sue continued to enjoy complete pain relief.
Despite cessation of both infusions after the 4th day, Sue remained completely pain free.
Sue had physiotherapy and was able to bear weight on her CRPS-affected ankle without pain. Her ankle joint had full range of motion.
Upon discharge, Sue returned to cadet training. Half a year later, she was still pain free and able to perform all her cadet duties. Sue also enjoyed running without pain and was training for a marathon.
SUMMARY
This case highlights the importance of:
Early diagnosis; and
Timely and effective pain treatment
in CRPS.
1. The Importance of Early Diagnosis
Specifically, the earlier a diagnosis of CRPS is made, the less pain and suffering.
Early diagnosis of CRPS is a prerequisite to timely and effective treatment thereof.
In Sue’s case, her orthopaedic surgeon (one of her guardian angels!) diagnosed CRPS within only 1 week (!) after her ankle sprain.
Think about that! Only 1 week!!
2. The Importance of Timely and Effective Pain Treatment
If treatment for CRPS (via a precision nerve block or otherwise) is both timely and effective, this can lead to rapid recovery from CRPS.
Sometimes different treatments need to be tried out before the most effective treatment protocol is found.
Here, we learned that whilst partially effective, the 1st catheter (i.e. lateral sciatic catheter) was unable to block the residual pain on the lateral side of her lower leg, just underneath her knee.
In other words, Sue’s 1st Ropivacaine infusion was not properly placed to also block the cutaneous branches of the common peroneal nerve branches that innervate the lateral area of her lower leg, just below her knee.
As such, the anaesthetist (another one of Sue’s guardian angels!) replaced the original lateral sciatic catheter with a new posterior sciatic catheter (Everett et al, 2009).
It is clear that with a dedicated, professional and caring pain management team, the chances of recovery from CRPS are greatly enhanced.
In Sue’s case, her pain due to CRPS was completely eliminated within only 1 month. As such, Sue was able to return to an active and rewarding life and career shortly after.
This is good news for everyone!
KEY
*Lateral is the side of the body or limb that is away from the middle (i.e. farther from the middle).
* A popliteal fossa (a.k.a. knee pit) is a shallow depression behind the knee joint and knee cap.
* The sciatic nerve’s division into its tibial and common peroneal nerve branches was initially identified via ultrasound guidance.
This nerve’s division was identified via neurostimulation when the replacement posterior sciatic catheter was placed.
*Proximal means closer to the centre of the body.
REFERENCES
Peer-Reviewed Paper
(1) Everett et al. A Unique Presentation of Complex Regional Pain Syndrome Type I Treated with a Continuous Sciatic Peripheral Nerve Block and Parenteral Ketamine Infusion: A Case Report. Pain Med (2009);10(6):1136-9.
(2) Hancock et al. Diagnostic accuracy of the clinical examination in identifying the level of herniation in patients with sciatica. Spine (2011);36(11):E712-E719.
This blog post explores studies involving both children and adults with complex regional pain syndrome (CRPS) who underwent peripheral nerve blocks for pain relief.
ANATOMY OF A PERIPHERAL NERVE BLOCK
Peripheral nerve blocks are useful for diagnostic and/or therapeutic purposes.
An example of a brachial plexus infusion kit used for continuous nerve block
Continuously via infusion pump filled with a local anaesthetic; or
Via single injection of a local anaesthetic.
Local anaesthetics may include Bupivacaine**, Lidocaine, Mepivacaine** or Ropivacaine (Ropivacaine having less toxicity – see ‘Ropivacaine vs Bupivacaine’ section for more details).
There are many kinds of peripheral nerve blocks (e.g. upper limb blocks, lower limb blocks).
The brachial plexus is shown below. This comprises a complex network of nerves including roots and branches – some of which may targeted by a nerve block:
Chelly JE, ed. Peripheral Nerve Blocks: A Color Atlas. 2nd ed. Philadelphia, PA, Lippincott Williams & Wilkins; 2009: 20
The Feature Image at the top shows the innervation of the upper limb, some that may be affected by a nerve block.
Below, the branches of the lumbar plexus (left) and sacral plexus (right) that innervate the lower limb are shown, some that may be the precise target of a nerve block:
From Chelly JE, ed. Peripheral Nerve Blocks: A Color Atlas. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009: 76 and 79.
(1) A French Study Shows 100% Success Including Nil Pain Following 4-Day Continuous Nerve Block for Children with CRPS (N=13)
Details of French study
Introduction
According to a French study by Dadure et al (2005), recurring or intractable CRPS1 is not rare in children.
In this study, (the lesser toxic) Ropivacaine was used for performing continuous peripheral nerve block infusions in children with CRPS1 (N=13). Ropivacaine is considered less toxic than other local anaesthetics (see ‘Ropivacaine vs Bupivacaine’ section, below).
The average age of the children was 13, with ages ranging from 9 to 16.
The VAS Pain Scores prior to 4-day continual peripheral nerve block ranged from 8 to 10. This severe nerve pain was accompanied by allodynia, numbness, swelling and vasomotor disturbances.
The inciting event(s) for CRPS1 included sprains and traumas to ankles and wrists that occurred 6 to 8 months prior to peripheral nerve block.
4-Day Continuous Peripheral Nerve Block
While under general anaesthesia, nerve block was commenced by using a nerve stimulator to precisely locate the affected nerve. Once the catheter was in place, 0.5 ml/kg of a mixture on a 1:1 basis of 0.5% Ropivacaine and 1% Lidocaine (with Epinephrine) was injected via the catheter for 5 minutes.
Thereafter, a 20-minute Bier block* that involved anaesthesia of a limb was performed. A Bier block is sometimes called intravenous regional anaesthesia.
Specifically, the Bier block that led to regional anaesthesia involved draining blood out of the limb (via exsanguination), inflating a tourniquet* and intravenously injecting a local anaesthetic (0.2 ml/kg lidocaine, 1%) and other medication.
General anaesthesia was discontinued after completion of the Bier block.
A 96-hour ambulatory continuous 0.2% Ropivacaine infusion was commenced. Twelve (12) children had popliteal nerve blocks* while the 13th child was given an axillary nerve block*.
Results
Postoperative pain relief was excellent in all 13 children with CRPS1!
VAS Pain Scores decreased from 8 – 10 to NIL following 4-day ambulatory continual peripheral nerve block in ALL 13 children with CRPS1.
Motor nerve block was minimal before 12 hours, and non-existent thereafter. All children were able to walk after 24 hours.
Early discharge from hospital and continuation of the 4-day peripheral nerve block at home was rendered possible via the use of disposable catheter pumps.
Follow-Up
All 13 children had nil pain nor other symptom of intractable or recurrent CRPS1 at the 2-month follow-up.
Summary
The authors concluded that disposable continuous peripheral nerve block with Ropivacaine infusions may be an effective treatment for recurring or intractable CRPS1.
The 4-day Ropivacaine infusion offered complete pain relief and rapid mobility. This resulted in early discharge from hospital for all 13 children with CRPS1(Dadure et al, 2005).
A happy child is a happy life.
NERVE BLOCKS FOR ADULTS WITH CRPS
(2) A New Zealand Study – Peripheral Nerve Block for CRPS Patients (N=9)
Details
Nine (9) patients (5 females; 4 males) had severe CRPS including hyperalgesia and allodynia. The VAS Pain Scores were 9 or 10 (‘Worst Pain’) for 7 patients, and 7 or 8 (‘Severe Pain’) for the remaining 2 patients.
Many patients suffered pins and needles, tingling, numbness, redness of skin, sweating, hot or cold skin temperatures in their CRPS-affected limb as well as sleep disturbances.
The causes for CRPS varied greatly. Inciting events and injuries that led to CRPS included elbow injuries and traumas caused by crutching machine, blunt blows, a forklift blow and forceful gripping. CRPS also resulted following an injection into a thumb, a knee twisting injury, a fall onto a knee and an incident involving a hand and a 4WD door.
Treatment
These 9 CRPS patients (aged 22 to 61) were offered:
Peripheral nerve blocks;
Pain medications (e.g. carbamazepine, opiates); and
Bupivacaine (Marcain) trigger point injections for myofascial pain (in some patients)
from 2002 to 2003.
Peripheral Nerve Blocks
Three ml (3ml) of Bupivacaine was injected proximal* to the site of nerve pain. This was repeated every 2 – 3 weeks (maximum 3 injections). Treatment occurred in Invercargill (N=7) and Wellington, New Zealand (N=2).
Results
Seven (7) of 9 CRPS patients enjoyed significantly less hyperalgesia and allodynia after peripheral nerve blocks and other pain treatments.
Specifically, 5 patients enjoyed NIL pain more than 1 year after discharge. Another 2 patients had VAS Pain Score reductions from 9 to 1 or 2 two years after discharge (Kanji, 2006).
Conclusion of New Zealand Study
Peripheral nerve blocks together with pain medication may be a promising pain treatment for some CRPS patients.
(3) A Dutch Study – Continuous Axillary Brachial Plexus Blockade with Bupivacaine for 6 CRPS Patients (3 Successfully Treated)
Introduction
Axillary brachial plexus blockade* was offered for patients with severe upper limb CRPS (N=6).
Specifically, an indwelling catheter was placed within the neuromuscular sheath.
Regional anaesthesia was done either:
Continuously via portable infusion pump filled with Bupivacaine (0.5%, 3ml/hour); or alternatively,
Via a daily single dose of 20 ml Bupivacaine (0.25%) half an hour before therapy.*
Half (N=3) of the 6 Dutch CRPS patients benefited from brachial plexus blockade.
Details of all 6 patients follow:
Patient 1 (Unsuccessful Nerve Block due to Irritation at Catheter Insertion Site)
Sadly, Patient 1 (let’s call her ‘Eliza’) did not permanently benefit from brachial plexus blockade.
Eliza was 31 when she had right hand surgery for morbus Quervain.* Following casting, Eliza’s forearm was swollen and cold. Additionally, she had persistent and intense burning pain and severe allodynia in the right arm. A diagnosis of reflex sympathetic dystrophy (RSD; now called CRPS1) was made. Conventional pain intervention did not offer any relief and her arm lost all function due to severe muscle weakness.
Eliza was offered a continuous axillary brachial plexus blockade 2 years after she was first diagnosed with RSD.
The good news:
Within only hours of the continuous axillary brachial plexus blockade, Eliza’s right arm became warm, her pain decreased and the range of motion in her RSD-affected joints almost returned to normal.
The bad news:
Sadly, due to irritation at the catheter insertion site, Eliza’s continuous axillary brachial plexus blockade was stopped. Instead, she received a daily single dose of Bupivacaine.
Despite this, all of Eliza’s severe RSD symptoms returned within weeks after her continuous axillary brachial plexus blockade was discontinued.
Patient 2 (Successful Nerve Block)
Patient 2 (let’s call her ‘Alina’) was 39 when she suffered trauma including dislocation to her left shoulder during an epileptic seizure. After her dislocated left shoulder was repositioned, Alina felt a ‘burning diffuse pain’ in her left arm that was also swollen. Despite pain medication, Alina suffered severe allodynia and continuous burning pain in her entire left arm. Her left arm remained swollen, red, warm and sweaty. Her left hand’s range of motion was severely restricted and painful.
Nerve tests via electroneuromyography showed a small left brachial plexus lesion as well as deficient motor and sensory conduction velocity in her ulnar nerve. Alina was diagnosed with RSD following three-phase bone scanning.
Despite conventional pain treatment for 2 months, Alina’s RSD symptoms did not improve.
As such, Alina was offered a daily single dose of Bupivacaine.
The good news:
After receiving her first injection of Bupivacaine, she immediately enjoyed significant pain relief, reduced swelling and enhanced mobility. Her left hand function also improved.
After completing 2 sessions, Alina’s Bupivacaine treatment were no longer necessary. Alina’s RSD symptoms were vastly improved and lasting, as indicated at the follow-up appointment more than 1 year later.
Patient 3 (Unsuccessful Nerve Block due to Infection and Abscess)
Sadly, Patient 3 (let’s call her ‘Abby’) did not permanently benefit from brachial plexus blockade.
At 41 and while carrying glass bottles, Abby accidentally fell and severed 4 extensor tendons in her right wrist. Her forearm was casted following reconstructive surgery. Almost immediately afterward, her forearm became swollen. Furthermore, it switched from being red and warm to cold and blue. The cast had to be removed due to severe allodynia and continuous burning pain.
Despite conventional pain treatment for 2 months, Abby’s severe pain and swelling persisted. There was also excess hair and nail growth as well as wasting of skin.
Abby was diagnosed with RSD following three-phase bone scanning.
The good news:
Within a few hours of the continuous axillary brachial plexus blockade, Abby’s right forearm and hand became warm with significantly less pain and swelling. Abby was finally able to undertake physiotherapy.
The bad news:
Sadly,due to local infection at the catheter insertion site that spread to an abscess below the skin, Abby’s continuous axillary brachial plexus blockade was stopped after 3 sessions.
Following discontinuation of her nerve block, Abby’s severe pain and all of her other RSD symptoms and disability returned.
Patient 4 (Successful Nerve Block)
At 52, Patient 4 (let’s call her ‘Erin’) had right hand surgery due to Dupuytren contractures.* This was following up with a second hand operation to correct hand function. Erin had severe burning pain in her entire right arm that prevented her from sleeping, performing domestic chores and playing the piano.
Four (4) months later, Erin had severe pain, reduced sensation and swelling in her right hand. She was diagnosed with RSD following three-phase bone scanning.
The good news:
Erin underwent 3 sessions of continuous axillary brachial plexus blockade, during which she was pain free and able to do physiotherapy.
Despite minor contractures in several finger joints in her right hand (that compromised her ability to play the piano), her muscle strength fully recovered.
Patient 5 (Successful Nerve Block)
At 57, Patient 5 (let’s call her ‘Janet’) underwent casting following bilateral Colles fractures.* Her right hand remained painful.
Seven (7) later, Janet was diagnosed with RSD via three-phase bone scanning.
Janet received 4 sessions of daily single dose of Bupivacaine.
The good news:
These injections led to significant pain relief and enhanced muscle strength in her right hand.
After 2 months, all of her pain had vanished and her hand function including writing ability was restored.
The same results were confirmed at her 21-month follow-up appointment.
Patient 6 (Unsuccessful Nerve Block)
Sadly, Patient 6 (let’s call her ‘Lina’) did not permanently benefit from brachial plexus blockade.
At 43, Lina had RSD in her right leg for 7 years.
More recently and for unclear reasons, her right hand became painful, warm, red and swollen. Lina was diagnosed with RSD in her right hand.
Despite 7 months of conventional pain treatment, Lina had continuous burning pain and allodynia in her right forearm that was also cold. There was skin, nail and muscle wasting as well as severe contractures in her wrist and hand joints. Functional use of her right hand was impossible.
The good news:
Lina enjoyed immediate benefits upon commencing daily single dose of Bupivacaine. Her right hand became warm and the pain was reduced. After 3 sessions of Bupivacaine injections, Lina was able to perform activities using both hands.
The bad news:
Within only weeks after stopping Bupivacaine injection treatment,Lina’s pain and other RSD symptoms returned and functional activities using her hands were no longer possible.
Conclusion of Dutch Study
Three (3) of 6 CRPS patients (50%) benefited from axillary brachial plexus blockade.
Interestingly, the remaining 3 CRPS patients temporarily benefited from brachial plexus blockade. However, as soon as continuous axillary brachial plexus blockade was stopped (either due to irritation or local infection/abscess, as in Patients 1 and 3, respectively), pain and other symptoms of RSD returned.
Instead of a continuous axillary brachial plexus blockade, the 6th patient received daily single dose Bupivacaine injections.
The authors of this Dutch study asked a very interesting question (quoting):
‘Would continuous pain reduction with continuous axillary brachial plexus blockade (BPB1) have resulted in better functional use of the affected hand in activities of daily life and thereby improve long term effect? Continuous axillary brachial plexus blockadeseems more effective than daily single dose Bupivacaine injections (BPB2) in interrupting a … vicious [inserted: pain] circle and in preventing centralization and seems first choice when axillary brachial plexus blockade (BPB) is considered in treating severe RSD of an upper exteremity in which … exercises are not tolerated … Further studies are needed …’ (Ribbers et al, 1997; Ribbers, 2001).
In other words, would a better outcome have occurred if all 6 patients had continuous axillary brachial plexus blockade (assuming nil complications)?
(4) The English Patient with RSD
A 37-year old woman (let’s call her ‘Anne’) suffered neck (i.e. cervical) and shoulder pain as well as an occipital headache* following a car accident.
Six (6) weeks later, Anne endured pain in her left hand that was cold, blue, swollen and weak with reduced sensation.
Six (6) months later, Anne’s left hand was continuously painful (8/10), swollen, cold and in a semi-claw position. Following various tests, a diagnosis of RSD was made for the first time. (Unfortunately, Anne’s pregnancy had to be terminated following exposure to diagnostic tests that may have resulted in birth defects.)
Almost a year after her car accident, Anne was successfully treated with a 48-hour continuous axillary brachial plexus Bupivacaine block via a catheter inserted into her axillary sheath.
The good news:
Anne was finally free of pain during the Bupivacaine infusion! She was able to regain some movement of her hand and fingers during the next 2 weeks.
Since some of the pain in her left hand had returned, 2 more 24- to 48-hour continuous axillary brachial plexus Bupivacaine blocks were added to her care.
Six (6) hours after the infusion, Anne was (again) pain free. Furthermore, she regained a full range of movement in her left hand.
At her follow-up appointment 2 months later, Anne’s pain in her left hand was ‘minimal’ (1/10) and she continued to enjoy full movement of her left hand and fingers (Murray et al, 1995).
(5) An American Study – Continuous Infusion of Lidocaine Leads to Pain Relief in 5 CRPS Patients
Nine (9) patients with CRPS were selected for continuous subcutaneous 10% lidocaine infusion treatment. Four (4) patients had to discontinue this treatment.
Of the 5 who actually completed this treatment for 4 – 8 weeks, 4 were female (average age 47) while 1 was male. All 5 were diagnosed with CRPS 2.5 to 8 years earlier before commencing this treatment.
Post-continuous lidocaine infusion treatment , all 5 CRPS patients enjoyed less pain and allodynia. Their VAS Pain Scores decreased from 7 – 10 to 2 – 5.
There were also improvements in other CRPS symptoms (Linchitz & Raheb, 1999).
(6) A CRPS Patient in Saudi Arabia: Single Injection Nerve Block for CRPS
A 34-year old female patient (let’s call her ‘Azza’) suffered severe pain and allodynia (9 – 10 out of 10) in her left hand and wrist that was swollen, pale, cool, clammy, numb and weak. Azza also had limited movement in her left shoulder. Azza’s symptoms started 5 months ago although she could not remember any cause.
A diagnosis of CRPS1 was made.
Azza received an ultrasound-guided nerve block (i.e. interscalene brachial plexus block*). This nerve block that involved a single injection shot of 30ml Bupivacaine 0.25% resulted in complete pain relief in her left hand within a week.
Azza was also given a trigger point injection for spasms in her trapezius muscle that caused neck pain. At first, the trigger point injection involved lidocaine 2% infiltration. Two weeks later, Azza was offered another trigger point injection using botulinum toxin (BTX-A 100u; Botox) that finally led to lasting pain relief in myofascial trigger points in her trapezius muscle in her shoulder.
Azza’s functional mobility was restored via physiotherapy.
In summary and as confirmed at her 3-month follow-up, Azza enjoyed 100% pain relief from CRPS1, left hand, and full limb mobility following a single interscalene injection using Bupivacaine.
Azza’s neck pain caused by trapezius muscle spasms was completely resolved by a myofascial trigger point injection using Botox (Fallatah, 2014).
(7) Ulnar Nerve Block for RSD
A patient was diagnosed with upper limb RSD following radiography of blood vessels in the brain via the subclavian artery*. To enhance imaging, contrast injections are necessary.
Using a stimulator to identify the ulnar nerve in the axillary bundle, low volume injections including Bupivacaine 0.5% were given.
These injections led to pain relief and reversal of other RSD symptoms (Klein & Klein, 1991).
(8) A Slovenian Study Involving Continuous Sensory Analgesia for CRPS, Upper Limb
This review explores 21 CRPS patients who were screened for treatment involving continuous sensory analgesia via brachial plexus blockade.
In the first 2 days, all 21 patients underwent non-invasive therapy that included elevation of the CRPS-affected limb, cryotherapy and active exercises. Cryotherapy involves placing ice and cold packs near a painful area to reduce inflammation and soothe pain.
While 5 patients benefited from this non-interventional treatment, 16 did not.
As such, these 16 CRPS patient had continuous sensory analgesia of brachial plexus. This nerve block was done within 1 to 6 months after the inciting injury.
Patients were followed up from 3 months to 3 years after continuous sensory analgesia. Two (2) patients enjoyed excellent results (i.e. a completely normal hand), 11 patients had good results while 3 had poor results (Margić & Pirc (2003).
ROPIVACAINE vs BUPIVACAINE
Toxicity of Bupivacaine to Muscle Cells
Ropivacaine is a less potent local anaesthetic with an improved safety profile including lower muscle toxicity compared to Bupivacaine (Kaur et al, 2015).
An animal study found that Bupivacaine was toxic to muscle cells, especially in young rats.
Specifically, Bupivacaine led to bioenergetic alterations within the mitochondria*in muscle cells. This led to severe abnormalities in the muscle ultrastructure including damaged sarcomeres inside the muscle cells themselves (Nouette-Gaulain et al, 2009).
Selectivity of Ropivacaine for Sensory Nerves – Not Motor Nerves
Furthermore, at lower concentrations, motor nerves may remain unaffected throughout a Ropivacaine blockade (compared to Bupivacaine that initially blocks both sensory and motor nerves). This is due to the selectivity of Ropivacaine blockade for sensory nerves only.
Thus, reduced or nil pain sensation and unaffected motor nerves following a sensory nerve block with Ropivacaine may facilitate physiotherapy (Markham & Faulds, 1996).
SUMMARY
In summary, peripheral nerve blocks (together with other pain treatments) may offer significant relief from pain and other symptoms of CRPS.
This can only be good news!!
Sabina Walker
Blogger, Pain Matters (in WordPress)
KEY
*Mitochondria are the cells’ powerhouse or engine room and even have their own DNA.
*Sarcomeres are the ‘building blocks’ of our skeletal muscle cells.
*An axillary brachial plexus block (or axillary nerve block) is a nerve block for the lower arm (i.e. forearm) including elbow, wrist and hand.
An axillary corresponds to an armpit or part thereof.
Brachial pertains to the arm or part thereof.
* Exsanguination forces blood out of the limb, or part thereof. The use of an inflatable tourniquet prevents the return of blood flow into this area until desired.
* In a Bier block, a tourniquet is used to restrict local anaesthetic to a certain limb area and hence prevent it from entering circulation.
* A popliteal nerve block is a distal sciatic nerve block that leads to anaesthesia of the lower leg including calf, tibia, fibula, ankle, and foot.
Distal means further from the centre of the body.
*Proximal means closer to the centre of the body (e.g. spinal cord).
*Morbus Quervain, or de Quervain syndrome, involves pain and inflammation in the thumb including its tendons.
* Dupuytren’s contracture involves knots of tissue that form under the skin of the palm of a hand that leads to a deformed hand.
* A Colles fracture is a distal forearm fracture (ie broken wrist).
* Occipital headache may be caused by injury to head, neck and upper cervical spine that adversely affects the occipital nerves.
* An interscalene brachial plexus block is a proximal block of the brachial plexus.
* The subclavian artery delivers oxygenated blood from the base of the neck to the brain.
* Bupivacaine treatment was offered for a maximum of 2 weeks, followed by a 1-week ‘rest’ period. This was done to prevent infection, scar tissue and fibrosis as well as other complications at the catheter insertion and/or injection site. These 3-week cycles (aka sessions) were repeated as necessary.
** The local anesthetic, Mepivacaine, preferentially blocks sodium channel Nav1.8, while Bupivacaine inhibits TTX-sensitive sodium channels (Leffler et al, 2010).
REFERENCES
NERVE BLOCKS FOR CHILDREN WITH CRPS
(1) Dadure et al. Continuous Peripheral Nerve Blocks at Home for Treatment of Recurrent Complex Regional Pain Syndrome I in Children. Anesthesiology (Feb 2005);102(2):387–91.
(2) Kanji, Giresh. Treatment of Complex Regional Pain Syndrome with Peripheral Nerve Blocks: A Case Series of Nine Patients. Australasian Musculskeletal Medicine (June 2006); pages 1-10.
(3A) Ribbers et al. Axillary brachial plexus blockade for the reflex sympathetic dystrophy syndrome. International Journal of Rehabilitation Research (1997); 20; 371-380.
(7) Klein & Klein. Low-volume ulnar nerve block within the axillary sheath for the treatment of reflex sympathetic dystrophy. Can J Anaesth (Sept 1991);38(6):764-6.
(8) Margić & Pirc. The treatment of complex regional pain syndrome (CRPS) involving upper extremity with continuous sensory analgesia. European Journal of Pain (2003); 7(1):
(10) Kaur et al. Comparision between bupivacaine and ropivacaine in patients undergoing forearm surgeries under axillary brachial plexus block: a prospective randomized study. J Clin Diagn Res (2015);9(1):UC01-6.
(12) Leffler et al. Block of sensory neuronal Na+ channels by the secreolytic ambroxol is associated with an interaction with local anesthetic binding sites. Eur J Pharmacol (2010); 630:19–28.
Repetitive sciatic nerve blocks may offer substantial pain relief for some patients with nerve pain.
DETAILS
A 50-year-old woman (let’s call her ‘Jane’) suffered ongoing nerve pain in her left lower limb following surgery to remove a schwannoma* on her left S1 nerve root (aka sciatica nerve schwannoma).
Decades earlier aged only 27, Jane suffered ‘electric-like pain’ during intimacy. Shortly afterward, surgery was performed to remove a cyst on her left ovary. Despite surgery and nonsteroidal anti inflammatory drugs (NSAIDs), her pain persisted.
Several years later, a 3 cm surgical incision was performed to remove her left S1 nerve root at the plexus including a schwannoma.
Post-surgery, Jane endured pain upon sitting and touch. She also had a limp in her left leg.
Jane was prescribed NSAIDs, antidepressant and pregabalin. Despite these medications, Jane suffered ongoing mild pain. She also had intense pain at rest and movement as well as severe allodynia upon palpation in the area between S1 to L5 (VAS from 3 to 10).
Jane displayed mild motor weakness during nerve testing of her left lower leg (i.e. during leg abduction, foot eversion, plantar and toes flexion and in the hip extension).
Jane also had drastically reduced sensation in her foot, lower leg and thigh and buttocks.
A sciatic nerve block comprising an anesthetic mixture (20 mL) was injected at the ‘pain trigger point’ (located 1 cm above the midline of the incision).
RESULTS OF SCIATIC NERVE BLOCK
Guess what happened next??
Jane enjoyed immediate pain relief after this sciatic nerve block (VAS 1/10), after suffering years of pain!!
The sciatic nerve block’s pain relieving effects lasted 15 days. Despite her nerve pain returning 15 days later, Jane’s pain had lost its original intensity (VAS decreased to 3/10).
To better manage Jane’s nerve pain, a repetitive sciatic nerve block was prescribed.
SUMMARY
Some nerve pain patients may benefit from repetitive sciatic nerve blocks.
Sabina Walker
Blogger, Pain Matters (in WordPress)
*Usually benign in nature, a schwannoma is a nerve sheath tumour that develop from the Schwann cell.
REFERENCES
(1) Naja Z et al. Repetitive nerve block for neuropathic pain management: a case report. Scand J Pain (26 Jan 2018);18(1):125-127.
A single nerve block called a Greater Occipital Nerve Block (GON block) may lead to reduced migraine days and increased serotonin!
DETAILS OF MIGRAINE STUDY
Specifically, an Italian study involving 17 migraine patients and 19 healthy controls found that a single Greater Occipital Nerve Block (GON block) significantly reduced the total number of migraine days per month by 35%.
The GON block offered the biggest migraine relief in 11 of 12 patients who also endured Medical Overuse Headache (MOH). Medical Overuse Headache results from medication overuse.
Once the GON block’s effects wore off, episodic migraine returned in 8 of 17 patients.
It is thought that serotonin deficiency may contribute to migraines.
Thus, it is likely that enhanced serotonin release and increased central serotonergic tone resulted in migraineurs who enjoyed fewer migraine days following a single GON block.
The slope of the intensity dependence of auditory evoked potentials (IDAP) was significantly flatter in those patients who benefited from the GON block. Decreased IDAP values are linked with stronger central serotonergic tone.
A flatter IDAP slope as well as migraine relief offered by a single GON block are suggestive of changes in the brain (i.e. plastic brain changes, neuroplasticity) (Viganò et al, 2018).
SUMMARY
Migraineurs may benefit from a GON block.
Given that a single GON block led to 35% fewer migraine days per month and given that increased serotonin occurred (as indicated by a flatter IDAP slope), migraines may be (partly or fully) centrally mediatedin the brain by serotonergic mechanisms. Finally, these mechanisms may be modulated by a GON block.
A flatter IDAP slope as well as migraine relief offered by a single GON block are suggestive of changes in the brain (i.e. plastic brain changes, neuroplasticity) (Viganò et al, 2018).
All this is good news for migraine sufferers!
Sabina Walker
Blogger, Pain Matters (in WordPress)
REFERENCE
Viganò et al. Neurophysiological correlates of clinical improvement after greater occipital nerve (GON) block in chronic migraine: relevance for chronic migraine pathophysiology. The Journal of Headache and Pain (Dec 2018). 19: 73: pages 1-9.
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