7.10 (9.8) Interventional approaches for pain Flashcards
What are the two general indications for an interventional approach to pain management?
What are two general goals of an interventional approach to pain management?
indications:
(a) uncontrolled pain despite systemic analgesics
(b) unacceptable systemic analgesic adverse effects
Goals: improve pain control and/or allow opioid dose reduction
A patient has muscle pain and a palpable nodule is felt on examination. What is a trigger point?
What meds can be injection via trigger point injections? Name 3
Besides TP injection, name 3 other interventions that can be done for this patient at the site of their muscle pain
Trigger point: a HYPERIRRITABLE nodule in skeletal muscle that may be palpable, is painful on compression, and can cause characteristic referred pain and/or autonomic phenomena
TP drugs:
- Local anesthetic (lidocaine)
- Botox
- Steroid/NSAID
(ABS)
Treatment options that target trigger point:
- Acupuncture*
- Dry needling*
- Pulse radiofrequency
- Physical manipulation (massage, exercise)*
- TENS
List 2 medications that are generally used with intraarticular injections.
List 3 complications of intraarticular injections
corticosteroids are most commonly used
hyaluronic acid
infection, bleeding, nerve injury, joint destruction
What is the mechanism of action of botulism toxin?
List three clinical situations where it can be used for pain management.
What is the onset of effect post injection and duration?
A patient received botox and had an excellent effect for pain. 3 months later the injection is repeated with no appreciable change in pain. What is the mechanism for this loss of efficacy? What can be done to limit this?
BTX is a neuroparalytic agent produced by the bacterium Clostridium botulinum: irreversibly inhibits acetylcholine release at the neuromuscular junction –> reduce muscle contraction and painful muscle spasm; may also block peripheral sensitization and indirectly reduce central sensitization
BTX is used in spasticity and movement disorders, as an analgesic in migraine, phantom limb pain, complex regional pain syndrome, chronic myofascial pain
Onset 1 week post injection, last 3-4 months
Repeated administration may lead to diminishing benefit due to the development of neutralizing antibodies. An interval of >12 weeks between injections is recommended, and if positive effects are lost, they may be regained by using an alternative formulation.
WP: break into two cards?
List 2 common pain conditions indicating the use of regional (i.e. peripheral) nerve blocks.
What is the main medication generally utilized for these blocks?
A patient has a successful peripheral nerve block and is offered a catheter for ongoing blockage of the nerve. (1) What are three complications that can arise from catheter placement? (2) How long can catheter be maintained for?
perioperative (eg brachial plexus block for upper limb surgery) or chronic pain (diagnostic and therapeutic)
Local anesthetic = main med
complications of long term catheters - infection, local anesthetic toxicity, catheter displacement, or technical difficulties such as catheter knotting
Can be maintained for several weeks
List 3 methods for neurolysis
Radiofrequency (thermal)
Chemical (phenol and ethanol)
Surgical (open)
FS: neurolysis destroys nerves (permanent nerve blocks)
What is the indication for neurolysis?
Severe refractory cancer pain
List three chemicals frequently used for sympathetic nerve blocks
local anesthetic, botox, neurolytic solution (phenol)
FS:
- neurolytic block with phenol = permanent damage of nerve (a type of nerve block)
A patient has a local anesthetic block used to predict the effects of a sympathetic neurolytic block. The trial is a success but after neurolysis there is no pain relief. What might have taken place (two reasons)?
analgesic effect of absorbed local anaesthetic and/or placebo response.
List 5 common sympathetic nerve blocks performed (and their corresponding areas of pain relief)
stellate ganglion block -> upper extremitiy celiac plexus block -> upper abdo pain lumbar sympathetic block -> lower extremity superior hypogastric plexus block -> pelvic pain ganglion impar block -> perineal pain
FS: SC L SG
List four clinical condition for a stellate ganglion block
Angina*
inoperable coronary artery disease
Upper extremity pain: ◆ complex regional pain syndrome* ◆ peripheral vascular disease ◆ Raynaud’s disease ◆ brachial plexus infiltration by tumour* ◆ herpes zoster ◆ phantom pain*
FS:
VIND (PVD, herpes, neoplasm, degenerative = phantom limb)
Celiac plexus block - name
- 2 indications
- 2 approaches
- Side effects (2 common and 2 rare)
Indications:
Visceral pain from -
- pancreatic cancer
- other upper abdominal tumours
Methods:
- percutaneous (fluoroscopy, CT or MRI)
- endoscopic US-guided transoesophageal
Immediate complications:
- diarrhoea
- orthostatic hypotension (usually transient)
Rare:
- paraplegia due to ischaemic spinal cord from injury or spasm of the artery of Adamkiewicz
- seizures
- aortic dissection
SEs = DOPA
List four clinical etiologies that would benefit from a lumbar sympathetic block
Intractable lower extremity pain: (most common indication) ◆ inoperable peripheral vascular disease* ◆ chronic painful leg ulceration ◆ complex regional pain syndrome* ◆ phantom pain* ◆ herpes zoster ◆ diabetic neuropathy*
Kidney pain (including ‘phantom kidney pain’)
Testicular pain
tenesmus
FS
VIND (PVD, herpes, rectal ca = tenesmus, degenerative - phantom pain)
What type of pain might necessitate a superior hypogastric plexus block? List three types of cancer that might cause this type of pain
Pelvic visceral pain
GI (colorectal), GU, Gyne cancer
What type of pain might necessitate a ganglion impar block
Intractable perineal pain
What is the aim of spinal (aka neuraxial) neurolysis?
What are 3 types of spinal neurolysis and their locations of interruption?
How is it accomplished?
Interrupting transmission of pain signals entering/though spinal cord
- Cordotomy - spinothalamic tract
- Myelotomy - dorsal midline
- Rhizotomy - dorsal roots (sensory neurons)
Open,RF, phenol or ethanol
A patient is bedbound and suffers from unilateral lower body pain. They are entering the last weeks of life and want to retain as much mental clarity as possible. Mobility and function are not a concern for the patient so long as they are mentally aware. What chemical intervention technique can be considered? What medications are used?
chemical cordotomy at the upper-lumbar dermatomal level
Medications: ethanol or phenol
2 types of pain indicating for spinal analgesic (epidural or intrathecal)
What is recommended before permanent spinal delivery system implantation
Indications:
- Deep constant somatic pain
- Neuropathic pain
Spinal analgesic trial through temporary catheter is recommended first
List four medications that are typically used for spinal analgesia. What is the mechanism of action of each of these agents?
Morphine is the most frequently used spinal analgesic for chronic pain, but other opioids (hydromorphone, fentanyl, and sufentanil) are also used.
local anaesthetics (bupivacaine, ropivacaine) - Na channel blocker
clonidine - alpha 2 adrengeric agonist
baclofen - gaba b agonist
FS:
A - anesthesia
B - baclofen
C - clonidine
D - opioids
List four side effects of spinal opioids
Most common spinal opioid adverse effects are those of opioid therapy in general - constipation, nausea, myoclonus, delirium, pruritus
***respiratory depression from spinal opioid therapy is uncommon, it can occur at initiation of treatment or with subsequent spinal catheter or pump adjustments. Occasionally, delayed respiratory depression (onset 3–20 hours) occurs, presumably as a result of cephalad opioid migration within the CSF
Other, more common adverse effects, such as endocrine abnormalities, sweating, and peripheral oedema, are associated with both systemic and spinal chronic opioid therapy
Difference between epidural and intrathecal analgesic in terms of effect on sensory or motor function
Epidural - less loss of sensory or motor function
List three contraindications to the use of spinal analgesics
Coagulopathy
Septicaemia
Local infection is a contraindication if a site free of infection cannot be found for spinal catheter system implantation
Immunosuppresion is a relative contraindication - although chemo and xrt not contraindications (XRT cannot include site)
List three complications from the use of spinal anesthetics (via catheter pump)
List one unique complication for epidural and intrathecal anesthesia
- Infection - site of catheter, meningitis, epidural abscess
- pump malfunction
- catheter dislodgement or disconnection
Epidural fibrosis - formation of scar tissue around the catheter within the epidural space
Subarachnoid - meningitis, catheter tip granuloma
A patient with an external subarachnoid catheter develops altered LOC, fevers, and HA. What diagnosis might you be concerned about? Does the catheter need to be removed? If so when?
Meningitis
If infection does not rapidly improve, the subarachnoid catheter should be removed (unless if patients at EOL)
