How lidocaine gtt 2/2 drip help in migraine pain ?
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lidocaine infusion migraine treatment
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intravenous lidocaine migraine refractory
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PMID: 34894295
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PMID: 35609890
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Here is a detailed explanation of how a lidocaine 2% drip (gtt) helps in migraine pain:
Lidocaine Drip (2 mg/mL / 2 mg/min) in Migraine
What "Gtt 2/2" Means
"Gtt 2/2" in the clinical context typically refers to a continuous IV infusion of lidocaine at 2 mg/mL concentration running at 2 mg/min (or sometimes a weight-based protocol starting at 1-2 mg/kg). It is used in inpatient/hospital settings for refractory migraine - migraine that has not responded to standard therapies.
Mechanism of Action
Lidocaine is a Class IB sodium channel blocker. In migraine, it works through several interconnected mechanisms:
1. Sodium Channel Blockade - Core Mechanism
- Lidocaine blocks voltage-gated Na+ channels (specifically Nav1.1, Nav1.7, Nav1.8) on nociceptive trigeminal nerve fibers
- This suppresses ectopic neuronal firing and repetitive action potentials that propagate pain signals from the trigeminal nucleus caudalis to the cortex
- In migraine, trigeminal sensory fibers innervate intracranial blood vessels and meninges; lidocaine dampens their hyperexcitability
2. Inhibition of Central Sensitization
- Sustained migraine leads to central sensitization - a state of neuronal hyperexcitability in the trigeminal nucleus and thalamus
- IV lidocaine, by systemically reaching the CNS, reduces this central sensitization and helps "break the pain cycle"
- This is why it is particularly useful in status migrainosus or refractory chronic migraine
3. Suppression of Cortical Spreading Depression (CSD)
- CSD is a wave of neuronal and glial depolarization that propagates across the cortex and is believed to trigger migraine aura and headache
- Lidocaine, via Na+ channel blockade, can suppress CSD propagation, reducing both aura and the downstream activation of trigeminal pathways
4. Anti-inflammatory and Anti-nociceptive Effects
- At systemic levels, lidocaine inhibits neurogenic inflammation - the release of substance P, calcitonin gene-related peptide (CGRP), and other neuropeptides from trigeminal nerve terminals around meningeal vessels
- CGRP is the primary mediator of neurogenic vasodilation and pain in migraine; dampening its release is a key therapeutic target
5. Modulation of NMDA and AMPA Receptors
- Lidocaine also has some NMDA receptor antagonist activity, contributing to its anti-sensitization effect in the dorsal horn and trigeminal nucleus
Clinical Use Protocol
| Parameter | Detail |
|---|---|
| Setting | Inpatient / monitored infusion unit |
| Indication | Refractory migraine, status migrainosus, refractory chronic migraine |
| Dose | IV 1-2 mg/kg loading, then continuous infusion 1-3 mg/min (titrated) |
| Duration | Typically 3-7 days in hospital ("multiday infusion") |
| Monitoring | Continuous cardiac monitoring (ECG), BP, plasma lidocaine levels |
| Adjuncts | Often combined with ketorolac, magnesium, dihydroergotamine (DHE), methylprednisolone, neuroleptics |
A rapid one-time abortive dose is 100 mg IV bolus (as listed in Morgan & Mikhail's Clinical Anesthesiology) for acute migraine.
Evidence Base
A large retrospective analysis of 609 hospital admissions (Schwenk et al., Reg Anesth Pain Med 2022) found:
- Median pain score dropped from 7.0 to 1.0 by end of hospitalization (p<0.001)
- 87.8% of patients were acute responders
- 43% remained sustained responders at 1 month
- Nausea/vomiting were the most common (mild) side effects
A 2021 review by Mojica et al. in Current Pain and Headache Reports (PMID: 34894295) confirms that in carefully monitored inpatient settings, IV lidocaine and ketamine infusions are increasingly used when the standard Raskin protocol (DHE + antiemetic) fails.
From Tintinalli's Emergency Medicine: "A small number of studies using IV lidocaine (50-150 mg or 1-2 mg/kg) for ED migraine management show no consistent benefit vs. standard therapy (morphine, ketorolac, DHE, chlorpromazine)" - so in the ED setting, lidocaine is not considered first-line.
Important Caveats
- Not a first-line treatment - reserved for refractory cases after triptans, DHE, antiemetics, and NSAIDs have failed
- Requires continuous cardiac monitoring - risk of arrhythmias, hypotension, CNS toxicity (tinnitus, perioral numbness, seizures at toxic levels)
- Plasma lidocaine levels should be checked during multiday infusions (therapeutic range 1.5-5 mcg/mL; toxicity >5 mcg/mL)
- Evidence is mostly from retrospective studies; prospective RCTs are still needed
In summary: Lidocaine drip in migraine works primarily by blocking Na+ channels on trigeminal nociceptive fibers, suppressing central sensitization, inhibiting CGRP-mediated neurogenic inflammation, and possibly suppressing cortical spreading depression - collectively "breaking" the sustained pain cycle in refractory migraine. - Morgan & Mikhail's Clinical Anesthesiology, p. 2023; Tintinalli's Emergency Medicine, p. 3425
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