Pain management in neurosurgical patients

Pain management in neurosurgical patients

Dr. Tushar kumarDA,DNB

PDCC Neuroanaesthesiology

Introduction:

• In neurosurgical patients pain has often being overlooked and traditionally has been a subject of inconsistent research.

• No consensus regarding the standardizationof pain control.

• Pain after craniotomy is moderate to severe and inadequately treated in approximately 50% of patients.

Anesthesiology Clin; 25 (2007) 655–674; Perioperative Pain Management in the Neurosurgical Patient ; Jose Ortiz-Cardona, MD, Audre´e A. Bendo, MD*

BioMed Research International; Pain following Craniotomy: Reassessment of the Available Options; Rudrashish Haldar, Ashutosh Kaushal, Devendra Gupta, Shashi Srivastava, and Prabhat K. Singh; Volume 2015, Article ID 509164, 8 pages

Introduction:• Various techniques and approaches, based on the

latest research and clinical trials.• The greatest challenge in managing neurosurgical

patients is the need to assess neurologic function while providing superior analgesia with minimal side effects.

• To achieve this goal, a multimodal approach to analgesia using various drugs and techniques is an ideal choice.

Rahimi SY, Vender JR, Macomson SD, et al. Postoperative pain management after craniotomy:evaluation and cost analysis. Neurosurgery 2006;59(4):852–7

What is pain?

Pain, as defined by the International Association for the Study of Pain, is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage or both.

It is an individual experience, with unique properties varying from patient to patient.

Physiology of pain:Myelinated A delta afferent nerve fibers. These are fast conducting, have low threshold for activation.Stimulus is sensed by nociceptors free nerve endings located in the skin, muscles, joints, and mucosa, and in visceral organs.

Unmyelinated, slow C fibers. Polymodal nociceptors respond tohigh-intensity mechanical or chemical stimuli, and cold-hot stimuli.

Pain pathways:

Vasodilatation, plasma extravasation activation of nociceptors

Release on inflammatory mediators, substance P, calcitonin - GRP

communicated with cell bodies of sympathetic nervous system and ventral motor nuclei

Impluse generation

Primary afferent neuron to dorsal horn of spinal cord

Synapses to form second order neuron

Synapses at thalamus to form 3rd order nerves

Relay in somatosensory cortex

2nd order nerves transmit pain , temperature and light touch

Also transmit axonal br to reticular formation, nucleus raphe magnus, periaqueductal grey matter and other area of brain stem.

Pain in neurosurgery:• Pain experienced by patients after craniotomy

is of somatic origin, most likely involving the scalp, pericranial muscles, and soft tissue, and from manipulation of the dura mater.

• Correlation between the site of the surgical wound and the pain.

• Subtemporal and suboccipital surgical routes gives highest intensity of pain.

Innervations:• The scalp receives its innervations from cervical plexus and

the trigeminal nerve. • The anterior scalp: supraorbital and supratrochlear nerves,

divisions of the frontal nerve (ophthalmic division of trigeminal nerve).

• The temporal scalp: zygomaticotemporal (maxillary division of trigeminal nerve), temporomandibular, and auriculotemporal nerves (mandibular division of trigeminal nerve).

• The occipital scalp: cervical plexus greater auricular, and the greater and lesser occipital nerves.

• The dura mater is innervated by nerves that accompany the meningeal arteries.

Innervations:

Causes of inadequate pain controlNeurosurgical patients require frequent neurological

examinations.But excessive sedation camouflages the new onset neurological deficits and hamper the neurological

response monitoring.

Respiratory depression Hypercarbia ↑ ICP.

Inadequate analgesia agitation, hypertension, shivering, and vomiting which may increase the risk of intracranial bleeding or other neurologic complications

Causes of inadequate pain control

2. Defective communication, altered mental status or neurologic deficits.

3. Patients undergoing spine procedures, pain is often a source of significant preoperative distress.

‘‘chronic pain patients’’ require high doses of narcotics to achieve satisfactory analgesia.

Consequences of inadequate pain control:

Classification of Headache Disorders

• International Classification of Headache Disorders (ICHD-3) published by the International Headache Society.

• They classified Postcraniotomy headache and subdivided it into acute and persistent varieties.


• Acute Headache Attributed to CraniotomyDescription. Headache is of less than 3 months’ duration caused by surgical craniotomy.

• Diagnostic Criteria. They are as follows:(A) Any headache fulfilling criteria (C) and (D).(B) Surgical craniotomy which has been performed.(C) Headache which is reported to have developed

within 7 days after one of the following:


(1) the craniotomy,(2) regaining of consciousness following the craniotomy,(3) discontinuation of medications that impair ability to

sense or report headache following the craniotomy.(D) Either of the following:(1) headache resolved within 3 months after the

craniotomy,(2) headache not yet resolved but 3months have not yet

passed since the craniotomy.(E) Not better accounted for by another ICHD-3 diagnosis.


Persistent Headache Attributed to CraniotomyDescription. Headache is of greater than 3

months’ duration caused by surgical craniotomy.

Pain assessment

Pain History– O – Onset – P – Provoking / Palliating factors– Q – Quality / Quantity– R – Radiation– S – Severity – T – Timing

Pain assessment: VAS

Pain assessment

Pain assessment in spinal surgeries: 1. McGill pain questionnaire.2. The Brief Pain Inventory3. The Roland Morris disability questionnaire4. Oswestry disability index (ODI)/neck

disability index (NDI)

Pain assessment: Headache score

Methods to Treat Pain• Non-Pharmacologic

• Pharmacologic– Medications (po, iv, im, sc, pr, transdermal)

• Acetaminophen• NSAIDs• Opioids• Gabapentin• NMDA antagonists• Alpha-2 agonists

– Procedures• Regional Anesthesia• LA infiltration at incision site

Methods to Treat PainNon pharmacological methods include:1. Avoidance of trigger factors.2. Behavioural approaches: relaxation techniques,

biofeedback, 3. Cognitive- behavioral therapy but require

specialist time or technical devices.4. Acupuncture is controversial because of

methodologic difficulties. But studies acknowledge their efficacy.

5. Radiofrequency or cryoablation, 6. Physiotherapy,

Multimodal Analgesia

B. Pharmacologic :Using more than one drug for pain control

– Different drugs with different mechanisms/sites of action along pain pathway

– Each with a lower dose than if used alone– Can provide additive or synergistic effects– Provides better analgesia with less side

effects (mainly opiate related S/E)

Methods of analgesia for craniotomy:B. Pharmacologic methods:

1. Opioids:• stimulation of μ and k receptors.• Inhibition of voltage-gated calcium

channels and an increase in potassium influx.

Opioids inhibit the transmission from afferent first neuron to the second neuron.

Pharmacologic methods: opioids

• Intermittent boluses cause oversedation (peak opiate effect) followed by periods of inadequate analgesia.

• Patient-controlled analgesia (PCA) with morphine or fentanyl used effectively.

• Side effects • nausea, • vomiting, • decreased gastrointestinal motility, • pruritus, • respiratory depression, • oversedation.


As a consequence: Additional pharmacologic intervention.

Increased length of hospital stay.

Hindrance to postoperative neurologic examinations.


• Morphine: Intravenous (including PCA) or i.m. routes. Blunt the haemodynamic surges.

• Fentanyl: compared to morphine, it is more potent, faster acting.Transdermal route also.

Shorter duration of action so preferred in PCA .• Tramadol: synthetic analgesic

Less potent.

2. Nonsteroidal anti-inflammatory drugs

Mechanism of action:

• Reversible, nonselective inhibition of the cyclooxygenase (COX) enzymes COX-1 and COX-2.

• COX acts on arachidonic acid to synthesize prostaglandins & thromboxane.

• Central and peripheral inhibition of prostaglandin-mediated activation of sensory pathways.

Nonsteroidal anti-inflammatory drugs

Drawbacks:• Platelet dysfunction

• Increased bleeding times.• Avoid in aneurysm repair, arteriovenous malformation

resection and hematoma evacuations.

• Asthma• AKI• Rash


• Paracetamol (acetaminophen): N-acetyl-p-aminophenol

• Paracetamol alone is not sufficient to provide adequate analgesia. *

• With opioids they are very effective.

* Verchere and colleagues

3. Alpha-2 adrenergic agonistsDexmedetomidine • Potent and highly selective alpha-2 agonist• Acts on presynaptic neurons in the spinal cord

dorsal horn.• Provides sedation and analgesia without

respiratory depression. Clinical applications:• Awake craniotomy, • Preoperative sedation• Fiberoptic tracheal intubation.

Alpha-2 adrenergic agonistsDexmedetomidine :• Opioid-sparing effects: reducing morphine

requirements by 60% .• They also have preemptive analgesic effect.• Sedation to arousal immediately for

neurologic examinations. • Side effect: Hypotension and bradycardia.

4. N-methyl-D-aspartate (NMDA) receptor antagonists

NMDA receptors are ligand-gated ion channels • Permit calcium, sodium, and potassium into

the cell.• Activated by glycine and glutamate.

Glutamate, sensitizes nociceptors, increasing the magnitude and duration of neurogenic responses to pain, even after the initial peripheral input has stopped.

They are not actually analgesic but antinociceptive.

Methods of analgesia for craniotomy:A. Regional analgesia:

1. Scalp block:• Decrease the amount of rescue pain medication

requests.• Increase the time between the end of surgery

and the first request for postoperative analgesics,• Lower pain score values in the early

postoperative period . • Lower pain scores lasting up to 48 hours a • Preemptive analgesic effect.

Methods of analgesia for craniotomy:

2. Wound infiltration:Preincision local anaesthetic injection:

– blunt the systemic responses to craniotomy – minimize bleeding with skin incision.

visual analog scale (VAS) scores remains comparable without LA inj.

Ayoub C, Girard F, Boudreault D, et al. A comparison between scalp nerve block and morphinefor transitional analgesia after remifentanil-based anesthesia in neurosurgery. AnesthAnalg 2006;103(5):1237–40.

Chronic pain after craniotomy• Suboccipital craniotomy : M/C • Causes: Dural traction

Cervical muscleDestruction Nerve entrapment Cerebrospinal fluid leakageFibrin glue or drilling leading to Aseptic meningitis.

• T/T: TENS, acupuncture, radiofrequency, physiotherapy.NSAIDs, paracetamol, or opioids, GABA analogues, sumatriptan.

BioMed Research International; Pain following Craniotomy: Reassessment of the Available Options; Rudrashish Haldar, Ashutosh Kaushal, Devendra Gupta, Shashi Srivastava, and Prabhat K. Singh; Volume 2015, Article ID 509164, 8 pages

Pain management in spine surgery

Considerations :• a. Risk factors : Psychologic, social profile, and

preoperative pain severity .• ‘‘Failed back syndrome’’ high baseline opiate

requirements• Anxiety • Frequent neurologic examinations .• Patient cooperation and awareness• Early ambulation

Pain management in spine surgery

1. Parenteral administration Opioids:a. Fear of sedation b. Respiratory depression, c. Intolerance to the doses required for adequate analgesia.

A multidrug approach is a better choice because of higher Patient satisfaction and decreased doses of opioids.


• NSAIDS as the sole medication is not sufficient to provide adequate analgesia.

• Ketorolac, given IM or IV, is the most investigated drug among the NSAIDS.

• It has good analgesic potency.• Opioid-sparing effect.

Remy C, Marret E, Bonnet F. State of the art of paracetamol in acute pain therapy.Curr Opin Anaesthesiol 2006;19(5):562–5.


• High-dose (120–240 mg/d), but not low-dose, ketorolac has been associated with nonunion following spine fusion surgery .

• Low-dose ketorolac, is a safe and effective adjuvant to an opioid-based regimen for acute postoperative pain management after spine surgery.

NSAIDs: Cyclooxygenase-2 inhibitors

Defective bone healing by NSAIDS. COX-2– dependent PGE2 produced at the early stage

of bone healing is a prerequisite for efficient skeletal repair.

• Paracetamol is safe option where NSAID’s need to be avoided in view of bleeding risks, asthma, or renal derangements*.

• COX -2 inhibitors , given for shorter duration does not affect bone healing.

* Journal of Craniovertebral Junction and Spine; Pain management following spinal surgeries: An appraisal of the available options, Sukhminder Jit Singh Bajwa, Rudrashish Haldar1

NMDA receptor antagonist

Ketamine decreases postoperative pain by its direct analgesic effects and preventing the nociceptive sensitization in CNS.

Reduce or reverse opioid tolerance.

Dysphoria, sedation, diplopia, salivation, nausea, and hallucination restricts its extensive use.

GABA Analogues: Gabapentin• Anti-epileptic drug, also useful in:

– Neuropathic pain.• Blocks voltage-gated Ca channels in CNS• Additive effect with NSAIDs• Reduces opioid consumption by 16-67%• Reduces opioid related side effects• Drowsiness if dose increased too fast• Dose: 300 – 3600 mg/day

Tremont-Lukats IW. Anticonvulsants for neuropathic pain syndromes: mechanisms ofaction and place in therapy. Drugs 2000;60(5):1029–52.

Steroids

• Steroids are anti-inflammatory drugs:

• Inhibit phospholipase A2, • Decrease in the expression of substance P at

the dorsal root ganglion.

SteroidsIntraoperative IV injection of 40-mg dexamethasone• Reduces postoperative radicular leg pain • Reduces narcotic use.

• Oral and intravenous steroid administration as well as Intraoperative irrigation.

Neuraxial administrationNeuraxial administration: IntrathecalOpioids Intrathecal (IT)• Preservative-free morphine.• Fentanyl

• Side effects as with iv route.• Prolonged continuous infusion of drug through

an IT catheter is not recommended because of the risk of cauda equina syndrome.

Neuraxial administration

Local anesthetics: • Local anesthetics is mostly in combination with

opioids or other adjuvants. • Doses 0.6 mg/kg/h of morphine with

bupivacaine .

• But they may show prolonged sensory and motor block which is not desirable.

Neuraxial administration: epidural

• Epidural opioids have a better safety margin• Low incidence of dose-dependent respiratory

depression and urinary retention.

The controversy: More invasive procedure is superior to the standard IV or IM route after spine surgery.


Opioid and local anesthetic:Ropivacaine, more favoured.Different techniques like A. Single and double catheters, B. Intermittent boluses, C. Patient-controlled epidural analgesia,D. Continuous infusion of medication.Epidural catheter can be placed intraoperatively can

be done by the surgical team under direct vision .


Other agents:Alpha-2 agonists can be combined with opioids,

local anesthetic, or both to potentiate their action.

They produce minimal respiratory depression when compared with opioids.

Duration of action is prolonged.

Newer possibilities: • Transcutaneous electrical nerve stimulationIt is an efficient and opioid sparing method.TENS applied before surgery and postoperatively

reduces opioid requirement.

• Extended release formulationsMultivesicular liposomes containing bupivacaine.Single dose produces analgesia for several days.

Newer possibilities:

Summary

Pain management in neurosurgical patients has been inconsistently recognized and inadequately treated.

An increased awareness of pain management along with advances has led to improved practice and perioperative care of patients.

The greatest challenge to managing neurosurgical patients is the need to assess neurologic function while providing superior analgesia with minimal side effects.

To achieve this goal, a multimodal approach to analgesia using various drugs and techniques should be preferred.

Thank you

Pain management in neurosurgical patients

Health & Medicine

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