Dr. Charles is Clinical Associate Professor Neurology, Rutgers–New Jersey Medical School, Newark, NJ; Neurology Attending, Holy Name Medical Center, Teaneck, NJ ( [email protected]).

Dr. Gallo is Interventional Radiology Attending, Holy Name Medical Center, Teaneck, NJ ( [email protected]).

DISCLOSURES

The authors have no financial relationships to disclose relevant to the manuscript. There was no sponsorship of, or funding for, the study.

Dr. Charles designed and conceptualized the study; analyzed study data and performed the statistical analysis ; and drafted the manuscript for intellectual content . Dr. Gallo had a major role in the acquisition of interventional sphenopalatine ganglion data.

ABSTRACT

Objective

Chronic refractory migraine patients who failed repetitive dihydroergotamine/dopamine infusion protocols and conventional preventives were treated with repeated low-dose ketamine-based parenteral protocols, followed by memantine-based preventive therapy, and observed for immediate reduction in pain intensity and headache frequency.

Methods

Ten patients were treated at an outpatient infusion center for 2 to 5 sequential days with AM and PM courses of intravenous diphenhydramine, prochlorperazine, and dihydroergotamine. A daily sphenopalatine ganglion block and low-dose intramuscular ketamine were given midday between treatments, with dexamethasone given on the last infusion day. The Numeric Pain Rating Scale was measured after infusion. Carryover effect was assessed 1 month and 2 months after infusion by headache frequency while being treated with memantine and various other preventive and abortive therapies.

Results

Reduction in headache pain of 71% was achieved at the end of the infusion period. Sedation was the only adverse effect. Decreased headache frequency persisted beyond the infusion period, with an 88.6% reduction in headache days per month at 1 month and a 79.4% reduction in headache days per month at 2 months, without adverse effects.

Conclusions

Data indicate that 1) repetitive low-dose, ketamine-based parenteral therapy, followed by memantine-based preventive therapy, reduced refractory headache pain and 2) the decremental effect on headache frequency persisted beyond the infusion period. Our results support the hypothesis that multimechanistic therapies might be better than single-modality treatment. More studies, with a larger patient population, are needed to confirm whether these multimodality ketamine/memantine therapies should become the preferred approach for these extremely disabled patients.

Chronic refractory migraine (CRM) degrades function and quality of life despite elimination of triggers and adequate trials of acute and preventive medicines that have established efficacy. This definition requires that patients with chronic migraine fail adequate trials of preventive drugs, alone or in combination, in at least 2 of 4 drug classes, including beta blockers, anticonvulsants, tricyclic antidepressants, onabotulinumtoxin A, and calcium-channel blockers. Patients must also fail adequate trials of abortive medicines, including both a triptan and dihydroergotamine (DHE), intranasal or injectable formulation, and either a nonsteroidal anti-inflammatory drug or a combination analgesic, unless contraindicated. 1-4

In 1986, Raskin published a nonrandomized, nonblinded study of 2 treatments for intractable migraine in which repetitive inpatient intravenous (IV) DHE, administered in the hospital, was statistically more effective than IV diazepam in terminating cycles of intractable migraine. 5 Most headache specialists have adopted the so-called Raskin protocol, as originally described or in any of several variations, as cornerstone therapy for CRM, chronic migraine, and prolonged status migrainosus. 6 However, DHE-based infusion protocols do not always effectively reset the brain’s pain modulatory pathways in chronic migraine immediately posttreatment and might not induce a meaningful carryover effect.

We present 10 patients with CRM who met criteria for refractory migraine, including failure to terminate their headache with repetitive DHE/prochlorperazine/diphenhydramine/ketorolac/dexamethasone IV protocols, with or without sporadic administration of a sphenopalatine ganglion block. We treated these patients multimechanistically with repetitive IV DHE, a dopamine antagonist, an antihistamine, sphenopalatine ganglion ( SPG) block, and low-dose ketamine, plus last-infusion-day dexamethasone, followed by outpatient oral memantine. Subsequently, we observed them for 2 months.

Ketamine is a phencyclidine derivative introduced the early 1960s as an IV anesthetic. Low-dose ketamine has been used successfully in the treatment of chronic pain. Today, increased interest in the application of low-dose ketamine includes cancer pain; treatment and prevention of acute and chronic pain, with and without neuropathic analgesia; ﬁbromyalgia; complex regional pain; and migraine. 7,8 The effectiveness of ketamine in different pain disorders may arise through different pathways and/or by way of activity at various receptor systems. Effects arise predominantly by noncompetitive antagonism of the glutamate N-methyl-D-aspartate (NMDA ) receptor. 7,8

Memantine also is an NMDA receptor antagonist that is used effectively as an oral agent in CRM. 9

METHODS

Patients enrolled in this prospective study had CRM for periods ranging from 1 to 2 years. All had daily headache that could not be terminated with repetitive DHE/prochlorperazine/diphenhydramine/ketorolac/dexamethasone IV protocols with or without sporadic administration of an SPG block. Age ranged from 18 and 68 years; all patients were female. Patients were excluded if they had known coronary artery disease, uncontrolled hypertension, or peripheral arterial disease; a history of stroke, transient ischemic attack, or pregnancy; impaired liver or renal function; smoked a tobacco product; or were taking a protease inhibitor or macrolide antibiotic.

Approval by the institutional review board was unnecessary because all drugs and procedures are FDA-approved and have published evidence-based efficacy for migraine and other diseases.

The Numeric Pain Rating Scale (NPRS; a scale of 0 to 10) was utilized to rate the intensity of pain from the beginning of the infusion to the end of the multiday infusion protocol, when the catheter was removed. All patients but 1 were treated for 5 days; for the 1 exception, treatment was terminated after 48 hours because of a scheduling conflict. The observational follow‐up periods for assessment of outcomes were 1 month and 2 months post-infusion.

Patients started the study with a baseline NPRS of 9 or 10. They were treated at the institution’s headache outpatient infusion center. In the morning, patients received, by sequential IV infusion, diphenhydramine, 50 mg; prochlorperazine, 10 mg; and DHE, 1 mg. They then received a midday SPG block under fluoroscopic guidance and ketamine, 0.45 mg/kg intramuscularly (IM), given in the post-anesthesia care unit. In the late afternoon, the patients received diphenhydramine, 50 mg; prochlorperazine, 10 mg; and DHE, 0.5 mg, in the Headache Outpatient Infusion Center. Patients were discharged to home by 6 PM. They received IV dexamethasone, 20 mg, on the last day of therapy.

Oral preventive agents were continued and abortives were temporarily discontinued during infusion therapy. Oral memantine was used immediately before, during, and, in all cases, after infusion, at a daily dosage that ranged from 10 mg BID to 28 mg, once-daily extended release.

RESULTS

Therapies were well-tolerated by all patients. On the last day of treatment, the entire cohort (N = 10) demonstrated an average of 71% (mean standard deviation [SD], 10.1%) reduction in pain intensity. The average reduction in headache days per month at 1 month was 88.6% (mean SD, 6.24%) and at 2 months was 79.4% (mean SD, 17.13%) ( Table). Adverse effects were mild temporary sedation from ketamine. Pulse oximetry revealed no abnormal decrease in O 2 saturation. All patients reported marked overall reduction in headache disability at the end of the infusion protocol. Self-administered abortive therapies posttreatment were more efficacious than they were pretreatment. All patients indicated less headache disability overall by the end of the 2-month observation period.



Table. Chronic Refractory Migraine Baseline Data and Treatment Results a

Name Age (y) Sex Treatment Duration (days) Baseline NPRS Post-treatment NPRS One Month Follow-up b Two Month Follow-up b SL 45 F 5 10 2 3 3 RR 44 F 5 9 1 1 3 MP 41 F 5 10 4 3 6 AP 35 F 5 10 3 8 15 SW 27 F 5 10 2 6 12 HC 47 F 5 10 4 4 6 KK 56 F 5 10 3 3 8 MG 53 F 5 9 4 2 3 DM 68 F 2 9 2 2 4 AO 18 F 5 9 3 2 2

aAll patients had daily headache at initiation of treatment.

bHeadache days/month.

NPRS, Numeric Pain Rating Scale.

DISCUSSION

In our study of 10 patients with CRM who had daily headache treated repetitively in an outpatient infusion center with multimodality therapies, including sub-anesthetic doses of ketamine, all patients experienced marked reduction in headache pain intensity, with a whole-group average reduction of 71% by the end of infusion treatment. During post-infusion observation, all patients continued various preventive therapies, including memantine. At 1 month, the average reduction in headache frequency was 88.6%. Two months post-infusion, the average reduction in headache frequency was 79.4%. Adverse effects were minimal. Overall, the treatment was found to be safe and efficacious. All patients felt less headache disability after 2 months.

Because the protocol was administered comfortably in the Headache Outpatient Infusion Center, the inconvenience and higher cost of inpatient parenteral treatment were avoided. Ketamine, 0.45 mg/kg IM is a sub-anesthetic dose with proven efficacy in treating migraine without adverse effects in an outpatient setting. 8 Low-dose ketamine obviated the need for anesthesia personnel and precautions. Temporary sedation was the only adverse effect. Ketamine was administered by a nurse in the post-anesthesia care unit while patients were under observation with conventional measurement of vital signs and pulse oximetry. Memantine, also an NMDA receptor antagonist, is postulated to prolong the NMDA antagonism of ketamine.

Inpatient and outpatient continuous IV DHE and repetitive IV DHE, often combined with dopamine antagonists in controlled and comparator studies, have demonstrated equal effectiveness for the treatment of chronic migraine. 5,10,11 Our patients failed these therapies. This raises the question: Should our combined multimodality, ketamine-based approach be standard parenteral therapy for CRM?

In a recent study of continuous inpatient single-modality IV ketamine, a less-impressive carryover effect was obtained, with 23% to 50% 1-month sustained responders. 12 Multimechanistic treatment superiority over monotherapy is legendary in the treatment of cancer and human immunodeficiency infection. Sumatriptan plus naproxen sodium as a single tablet for acute treatment of migraine resulted in more favorable clinical benefit compared with either monotherapy, with an acceptable, well-tolerated adverse effect profile. Because multiple pathogenic mechanisms putatively are involved in generation of the migraine symptom complex, multimechanism-targeted therapy may confer advantages over individual monotherapy . Drugs in 2 classes of migraine pharmacotherapy—triptans and nonsteroidal anti-inflammatory drugs —target distinct aspects of the vascular and inflammatory processes hypothesized to underlie migraine. 13

Although combination therapy for CRM has not been systematically studied in randomized trials, clinical experience suggests that a rational approach to CRM treatment, utilizing a combination of treatments, may be effective when monotherapy has failed. 14 During the infusion protocol, we re-set the trigeminovascular pain pathways 1) by repetitively blocking NMDA receptors (with ketamine), dopamine receptors (with prochlorperazine), and histamine receptors (with diphenhydramine); 2) by lidocaine anesthetic block of the sphenopalatine ganglia; and, on the last day of the protocol, 3) administering 1 large dose of IV dexamethasone to help prevent recurrence. 15 NMDA blockade continued with oral outpatient memantine.

Virtually all patients were taking other preventives during the pretreatment period and 2-month observation period, including topiramate, venlafaxine, beta blockers, candesartan, zonisamide, onabotulinumtoxin A, neuromodulation (Cefaly Technology), and transcranial magnetic stimulation (springTMS®). Self-administered abortives were more effective in the 2-month observational period; these included IM/IV DHE; oral, spray, and subcutaneous triptans; IM ketorolac; diclofenac buffered solution; and transcranial magnetic stimulation (springTMS®). The cornerstone strategy of our treatment group that was a constant was the use of low-dose IM sub-anesthetic ketamine at a dosage of 0.45 mg/kg/d and the use of oral memantine during the follow-up observation period, at dosages ranging from 10 mg BID to 28 mg, once-daily extended release.

Limitations of this study design are:

lack of a control group

lack of subject randomization for comparative outcomes

patients remaining on a variety of prophylactic regimens

patients permitted to take any rescue therapy.

The effect of repetitive SPG block cannot be teased out of the efficacy data, but many of our patients had a poor or temporary response to infrequent sporadic SPG blocks prior to participating in our protocol.

Many migraineurs who seek care in a headache clinic are refractory to treatment, despite advances in headache therapy; refractory migraine was found in 5.1% of these patients. 16 In this small series of patients, we demonstrated immediate relief and a significant 2-month carryover effect with our multimodality parenteral protocol. Larger, controlled studies are needed to further explore this protocol with repetitive DHE, diphenhydramine, prochlorperazine, SPG block, and low-dose IM ketamine, followed by outpatient memantine. Such studies would determine whether our protocol should be utilized as a primary treatment, instead of the conventional DHE-based Raskin and modified Raskin protocols.

Although this is a small series of patients, lack of adverse effects and impressive results should give credence to utilizing our protocol as treatment for this extremely debilitated, often desperate subset of headache patients. D ata indicate that, whereas ketamine combined with other therapies immediately reduced refractory headache pain, the ameliorating effect of ketamine on CRM headache frequency and pain in our protocol persisted beyond the infusion period. This phenomenon indicates a disease-modulating role for ketamine in refractory migraine pain, possibly by means of desensitization of NMDA receptors in the trigeminal nucleus caudalis—desensitization that continued with the NMDA receptor antagonist memantine and/or restoration of inhibitory sensory control in the brain.

CONCLUSION

Our results support the hypothesis that multimechanistic therapies, including low-dose IM ketamine and memantine, might be better than single-modality treatment in this debilitated, refractory population. Future studies, with larger patient populations, are needed to confirm whether these multimodality ketamine/memantine-inclusive therapies should become the preferred approach for these extremely disabled patients.

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