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Pain

Ketamine was approved by the FDA in 1970 and was originally used for the induction of anesthesia. It has been shown to relieve depression and is also widely used to treat pain. For depression, it is approved by the FDA in a nasal spray form. For severe pain, it is often given intravenously. Oral ketamine is probably the least effective.

In a recent study, Australian researchers compared the pain-relieving effect of oral and sublingual ketamine in 16 patients. The study was double-blind. Sublingual administration of ketamine resulted in a faster onset of pain relief – 7 minutes with sublingual and 13 with oral. Side effects were also more common with the sublingual route. In all other measures, sublingual and oral administration produced similar pain-relieving effects.

Oral and sublingual ketamine are not available at regular pharmacies. It is, however, easily made up by compounding pharmacies. The sublingual ketamine is available as a lozenge which is also called troche. I usually prescribe ketamine infusions or troches only after a wide variety of other treatments do not provide relief.

Ketamine is a controlled drug with a potential for misuse. It can also cause psychiatric side effects such as hallucinations, disinhibition, delusional thinking, and depression.

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The influence of estrogen on migraines in women is well established – women often experience migraines before or during menstruation and ovulation and their migraines usually subside during pregnancy and menopause.

According to a new study published this month by Dutch researchers, men who suffer from migraines often have a deficiency of male hormones.

Gisela Terwindt and her collaborators evaluated a possible deficiency of androgens or male hormones in 534 men with migraine and 437 men with cluster headaches. These men were compared to 152 healthy controls. Two validated questionnaires were used to measure androgen deficiency scores. The researchers controlled for age, weight (BMI), smoking, and lifetime depression. They also measured four sexual symptoms (beard growth, morning erections, libido, and sexual potency). These four symptoms have been shown to differentiate between hormonal deficiency from anxiety and depression. They did not perform blood tests to measure hormone levels.

Patients reported more severe symptoms of clinical androgen deficiency compared with controls. Both patient groups were more likely to suffer from any of the specific sexual symptoms compared to controls (18% migraine, 21% cluster headache, 7% controls).

The findings in men with cluster headaches are not surprising. Prior reports have documented low testosterone levels in this population. A small study by Dr. Mark Stillman suggested that those cluster patients who have low testosterone levels could benefit from hormone replacement therapy.

There are also reports of low testosterone levels in men with chronic migraines but the connection is less established.

This study may prompt me to pay more attention to sexual dysfunction in men with chronic migraines. I may also start checking testosterone levels in such patients.

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The placebo effect is a bane of clinical trials. It is, however, a great tool in clinical practice. It is unethical to prescribe an actual placebo but there is no reason not to try to enhance the placebo effect when prescribing any treatment, pharmacological or non-drug.

A new and unique study that was just published in Pain, a journal of the International Association for the Study of Pain, suggests that looking at others who respond to treatment makes people more likely to respond to that treatment as well.

German researchers decided to study what is called social observational learning (SoL). This was a double-blinded randomized controlled clinical trial in 44 patients with chronic low-back pain (CLBP). They compared the effects of observing positive treatment outcomes in a sham or pretend patient versus hearing the same sham patient report neutral effects. In the SoL group, the sham patient told study patients about his improved pain due to amitriptyline and he also demonstrated his improved mobility by bending forwards and sideways. The same sham patient told the control group only that he was taking amitriptyline. The researchers collected data before and after the intervention and two weeks later. After the intervention, pain decreased in both groups with no difference between groups. The SoL group, however, showed a significantly larger decrease in perceived disability.

The authors concluded that “The CLBP patients’ direct observation of positive treatment outcomes in the sham patient appears to have enhanced the treatment effects, while indirect verbal reports of reduced pain did not.”

These findings are not surprising. I often have patients ask for a particular treatment because their friend or relative had a very good response to it. If it is a reasonable treatment for a particular patient, I usually oblige, hoping for an enhanced placebo effect.

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Many migraine sufferers report that their migraines are brought on by the weather. High humidity, high temperatures, and changes in barometric pressure are the most commonly reported triggers. I’ve seen some patients for whom changes in the weather is the only trigger. Research studies looking at this connection, however, have been contradictory.

A very large study just published in Pain, the journal of the International Association for the Study of Pain examined a possible connection between the weather and pain tolerance.

The data from 18,000 Norwegians aged 40 years or older from the general population were examined. All of them underwent pressure pain tolerance (PPT) test using a blood pressure cuff and cold pain tolerance (CPT), tested by immersing the dominant hand in cold water.

The results showed a clear seasonal variation in CPT. Cold pain tolerance was worse during the warmer times of the year compared with January. There was no seasonal variation in PPT.

The authors also found that temperature and barometric pressure have “a causal and dynamic effect on pain tolerance, which supports the common belief that weather affects pain.”

There is not much you can do about the weather except for moving to a place with an unchanging and mild climate. Some of my patients with barometric pressure-induced headaches do respond to acetazolamide (Diamox). This is a diuretic that prevents mountain sickness in climbers. Patients do not need to constantly check the weather forecast. For more information on acetazolamide, see my previous blog post.

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The placebo effect is a bane of clinical trials. A drug is considered ineffective if it is only as good as a placebo. And placebo can be quite good. Intriguingly, the placebo effect in clinical trials has been getting stronger over the past few decades. Lately, placebo has been receiving a lot of attention from researchers.

A rigorous study just published in the journal Pain looked at the effect of a placebo when patients were clearly told that they are taking a placebo. These patients were compared to those who were given a placebo in a double-blind study of peppermint oil capsules for irritable bowel syndrome (IBS). These two different types of placebo were compared to a control group of patients who were not given any pills.

Participants treated with an open-label placebo and a double-blind placebo reported similar and clinically meaningful improvements in IBS symptoms. These improvements were significantly greater than in those who were not given any pills. The results were statistically significant for the primary outcome measure (IBS Symptom Severity Scale) as well as for mean global improvement scores.

Twice as many patients in the double-blind placebo group had side effects (mostly gastrointestinal, such as heartburn) than those in the open-label placebo. It is probably because the first group was told about the possible side effects of peppermint oil.

The authors concluded that an open-label placebo “could play a role in the management of patients with refractory IBS”.

Just like migraines, IBS involves central sensitization and hypersensitivity of the nervous system. And just like with migraines, placebo response in clinical trials of IBS tend to be high. This is not to suggest that these conditions are psychological. Especially with migraines, the biological basis is well documented. Psychological factors, however, cannot be ignored. About 40% of patients with chronic pain, including migraines, have a history of emotional, physical, or sexual abuse. Post-traumatic stress disorder of other types also causes hypersensitivity of the central nervous system. Psychological factors can even be the cause of such potentially deadly conditions as broken heart syndrome (Takotsubo cardiomyopathy). It is likely that the placebo effect is stronger in conditions where psychological factors are more pronounced.

It is considered unethical to prescribe a placebo to patients without telling them that they are getting a placebo. This latest study suggests that some patients may improve even if they know that they are taking a placebo.

I do prescribe herbal supplements such as feverfew and boswellia and on a rare occasion, a homeopathic remedy, all of which lack rigorous proof of their efficacy. For that matter, many drugs we prescribe for migraines lack such definitive proof. I would suggest that we should first prescribe less harmful unproven remedies rather than unproven prescription drugs.

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Many patients with chronic migraines complain of memory, word-finding, and other cognitive difficulties. I tell them that once we find an effective treatment for their migraines, their cognitive abilities should improve. I explain that the barrage of pain messages disrupts the normal flow of information in the brain.

“Association between chronic pain and long-term cognitive decline in a population-based cohort of elderly participants” is the title of a study published in a recent issue of the journal Pain. The French researchers followed elderly chronic pain patients for up to 15 years.

They concluded that “Chronic pain is associated with a higher cognitive decline, particularly in processing speed. This result reinforces the importance of actively treating chronic pain with pharmacological and nonpharmacological strategies to prevent its consequences, including cognitive consequences.”

This also applies to chronic migraines. Fortunately, we have many new and not so new highly effective pharmacological and non-drug therapies that can provide relief to well over 90% of chronic migraine suffers. Check out my new book, The End of Migraines: 150 Ways to Stop Your Pain.

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Trigeminal neuralgia (TN) is an extremely painful and often debilitating condition. Many people respond to the standard therapy with epilepsy drugs such as carbamazepine (Tegretol) or oxcarbazepine (Trileptal). Botox injections can be helpful as well. A significant minority of patients, however, do not respond to these treatments and sometimes require brain surgery.

Fortunately, we have a new class of drugs that has allowed some of my patients to avoid having an operation. These drugs are CGRP monoclonal antibodies (mAbs). They have been approved by the FDA only for the prevention of migraine headaches, so their use for TN is considered to be “off-label”.

The first case series was reported in 2019 by the Cleveland Clinic doctors. They found that six out of eight TN patients had a good response to erenumab (Aimovig).

A group of Israeli physicians published another case series in the current issue of Neurology. They found that nine out of ten TN patients obtained very good relief from erenumab.

Erenumab was the first CGRP mAb. It was approved in May of 2018. Another two, galcanezumab (Emgality) and fremanezumab (Ajovy) were approved about six months later. These are given by a monthly subcutaneous injection. About a year ago, an intravenous CGRP mAb, eptinezumab (Vyepti) was also approved. These four drugs are very similar. However, some patients find one to be more effective than others. I’ve found this to be true not only in migraine patients but also in those with TN. Erenumab is slightly different in its mechanism of action and it is the only one that has a warning about the potential for causing severe constipation and increased blood pressure. Since TN patients tend to be older and more prone to these side effects, I prefer galcanezumab or fremanezumab. Unlike eptinezumab, they can be self-administered.

Off-label use is totally legitimate. However, insurance companies are not likely to pay for an expensive drug that is not explicitly approved by the FDA for a specific indication. And these drugs are not cheap – about $600 to $700 for each monthly shot. Because of the competition among pharmaceutical companies, they provide us with plenty of free samples (except for eptinezumab). TN is a relatively rare disorder so we can provide free samples to all of our TN patients who respond to these drugs. This is true for most neurologists’ private offices. This may not be true in big hospitals where sampling is not allowed.

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Trigeminal neuralgia (TN) is an extremely painful condition. Patients describe the pain as electric shocks going through the face. The most common or classic form of TN is caused by the compression of the trigeminal nerve as it exits the brainstem by a blood vessel. TN can also be caused by multiple sclerosis (MS).

The pain of TN can be debilitating. Some people are unable to eat because of pain and become malnourished. The pain can interfere with speech. In some, it occurs unprovoked. In many, it leads to depression.

The first-line treatment is epilepsy drugs. These include carbamazepine (Tegretol) and oxcarbazepine (Trileptal). We also use Botox injections and the new preventive migraine drugs – CGRP monoclonal antibodies. If drugs and Botox fail, radiofrequency destruction of the nerve can be of help. When none of this helps, surgery can be very effective.

The so-called microvascular decompression surgery involves opening the skull and placing a Teflon patch between the nerve and the blood vessel which presses on the nerve. Since TN in people with MS is not caused by the compression of the nerve, surgery is rarely undertaken.

This is a very delicate surgery and should be performed by a neurosurgeon who has done many of such operations (yes, it’s a conundrum – how do surgeons become experienced if nobody wants to be one of their early cases). Sometimes, even if surgery is performed well, the pain persists.

Fortunately, a group of Canadian researchers found a way of predicting who is likely to respond to decompression surgery. In a study just published in the journal Pain, they described a special MRI scanning technique that predicted the success of surgery with high accuracy. They discovered that if the trigeminal nerve fibers are disrupted inside the brainstem rather than after they exit the brainstem, surgery was much less likely to help. This applied to both patients with classic TN and TN due to MS.

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The opioid epidemic has claimed many lives. Overprescribing by doctors has certainly played a role. The push to use opioids more liberally started in the late 1980s. This promotion by many pain experts even led to pain being adopted as the fifth vital sign. One impetus for this push was the mistaken belief in the low rates of addiction when opioids are used to treat pain. Another was the results of surveys of patients being discharged from hospitals. Poor pain control was the main complaint of 40% of such patients. Centers for Medicare & Medicaid Services (CMS) got into the act as well and included good pain control as one of the measures required for the recertification of hospitals. In January 2018, however, the three survey questions about pain management were replaced by three questions about communication about pain. In October of 2019, even these three items about communication about pain were completely removed from the CMS’ HCAHPS Survey. So hospitals and doctors no longer need to worry about relieving pain and the suffering that goes with it. Doctors have to worry more about losing their license or even being put into jail. I’ve testified in front of a disciplinary panel on behalf of a doctor who was at risk of losing his license. An adult patient’s mother complained to the state health department about her son getting prescriptions for opioid drugs. In this case, the doctor was exonerated but the financial and the emotional toll will certainly make him very unlikely to continue prescribing opioids drugs.

These drugs, despite their potential for causing addiction and other side effects, are life-savers for many people. When used judiciously and as part of a multidisciplinary approach, they can provide not only improved quality of life but can make a difference between disability and normal functioning.

A study just published in the journal Pain looked at the difficulties patients taking opioid drugs have in finding a primary care doctor.

This study examined if primary care clinics “are more or less willing to accept and prescribe opioids to patients depending on whether their history is more or less suggestive of aberrant opioid use”. They conducted an audit survey of primary care clinics in 9 states from May to July 2019. They had simulated patients call the clinics and give one of two scenarios for needing a new provider: their previous physician had either (1) retired or (2) stopped prescribing opioids for unspecified reasons. Of 452 clinics responding to both scenarios (904 calls), 193 (43%) said their providers would not prescribe opioids in either scenario, 146 (32%) said their providers might prescribe in both, and 113 (25%) responded differently to each scenario. Clinics responding differently had greater odds of willingness to prescribe when the previous doctor retired than when the doctor had stopped prescribing.

The authors concluded that “…primary care access is limited for patients taking opioids for chronic pain.” and that “This denial of care could lead to unintended harms such as worsened pain or conversion to illicit substances.”

Hopefully, the pendulum will soon begin moving closer to the middle. Another hope is that the researchers will finally discover the holy grail of pain management – a non-addictive pain medicine with few other side effects.

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The goal of personalized medicine will be achieved through the exponential growth of computing power. Epigenetics, pharmacogenomics, and machine learning are some of the approaches that are being driven by our ability to process massive amounts of data. Unfortunately, it may take another decade or two before we can offer our patients truly personalized medicine.

Until then, we still have to rely on clinical skills. In a study just published in the journal Pain, D. Bouhassira and his colleagues were able to predict the response of neuropathic pain to Botox injections. The prediction was based on a specific combination of symptoms and signs. They used the Neuropathic Pain Symptom Inventory (NPSI) in 628 patients to identify three distinct clusters of patients. The first group had a more severe pinpointed pain, the second one had more evoked pain, and the third had a higher score for deep pain.

The study included adult patients who had experienced pain for at least three months with a mean pain intensity three or greater on a 0 to 10 numerical rating scale. In more than 85% of the patients, neuropathic pain was due to a traumatic or surgical nerve injury. In the rest, it was due to postherpetic neuralgia (shingles).

The researchers used these three groupings to predicting treatment response through the analysis of their two previous controlled trials of Botox. They found significant effects of Botox compared to placebo in clusters 2 and 3, but not in cluster 1. They also developed and performed a preliminary validation of a web-based version of the NPSI and algorithm for the stratification of patients in both research and daily practice.

Botox is not yet approved by the FDA for the treatment of neuropathic pain. This means that insurance companies are unlikely to pay for it. Besides the pain of shingles, neuropathy, injured nerves (I’ve treated two patients with post-amputation pain), we use Botox “off label” to treat trigeminal neuralgia, cluster headaches, hemicrania continua, numular headaches, and other painful conditions. In one of my patients, even headache due to a large but benign brain tumor responded to Botox.

Botox helps such a wide variety of headaches and other painful conditions probably due to its proven effect on sensory nerve endings.

In treating migraine headaches with Botox, there were several attempts to find clinical predictors of response. More recent onset of chronic migraine and fewer days with migraine have been identified as predictors of a better response. . There have been also suggestions that eye pain was a good predictor of response to Botox. Patients with”exploding” (pressure from inside-out) headache may be less responsive than those with “imploding” (pressure from outside-in, or constricting pain) headache.

When studied in large groups, these features might have some predictive value. But it is not anywhere close to 100% or even 70%. Therefore, when dealing with an individual patient we would try Botox in patients with chronic migraines regardless of the presence or the absence of any of these symptoms.

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COVID-related lockdowns have saved many lives. We don’t yet fully appreciate, however, the other side of the ledger – the harms the lockdowns have caused. These include delays in diagnosing cancers, alcohol and drug abuse, depression, anxiety, deprivation of schooling and socialization in children, and worsening of pain and headaches. The latter not only because of lack of access to care but also due to the effect of loneliness.

Prior studies have shown that loneliness is consistently associated with pain. A study by British researchers published in the current issue of the journal Pain examined the question of whether loneliness worsens pain or pain leads to loneliness.

Drs. Anna Loeffler and Andrew Steptoe studied 4,906 men and women (mean age was 65) over a period of four years. They also looked at the role of inflammation in these people. Pain was defined by reports of being often troubled by pain at a moderate or severe intensity. Loneliness was measured using a standard scale. The researchers took into account age, sex, ethnicity, educational attainment, wealth as a marker of socioeconomic resources, marital status, physical activity, degree of mobility, and depressive symptoms.

They found that baseline loneliness was associated with pain four years later. Similarly, baseline pain independently predicted loneliness four years later. The likelihood of pain was increased when at the baseline loneliness was accompanied by an increase in an inflammation marker, C-reactive protein (CRP). On the other hand, inflammation did not predict future loneliness. Both pain and loneliness are distressing experiences that impact well-being and quality of life. The researchers concluded that the relationships between pain and loneliness are bidirectional.

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Many studies have shown that virtual reality experience can relieve pain. The first such study in burn patients was published 20 years ago. A comprehensive review of this topic, Immersive Virtual Reality and Virtual Embodiment for Pain Relief was published last year by Italian researchers.

A different group of Italian researchers tested the effects of visual distraction on pain in chronic migraine patients. They compared a classical hospital waiting room with an ideal room with a sea view. Both were represented in virtual reality (VR). They measured pain and brain responses induced by painful laser stimuli in healthy volunteers and patients with chronic migraine. Pain was induced in the hand of sixteen chronic migraine patients and 16 healthy controls. This was done during a fully immersive VR experience, where two types of waiting rooms were simulated. Patients with migraine showed a reduction of laser pain rating and brain responses during the sea view simulation. Control subjects experienced the same level of pain in both types of simulated rooms.

An older study of 30 patients with chronic pain showed that 20 patients had pain relief during a VR session. Ten of them reported complete pain relief. Of the 20 who had relief, 10 had continued relief after the VR session.

A combination of VR with biofeedback resulted in lasting benefits in 9 of 10 children with chronic headaches who completed 10 training sessions.

About 5% to 10% of people who try VR get cybersickness. This is a feeling of dizziness or vertigo, similar to motion sickness. This is why VR sessions are often limited to a maximum of 30 minutes.

It appears that there are several possible approaches to the treatment of pain using VR. One is by using VR for distraction. Another, by utilizing VR to facilitate biofeedback, which is proven to relieve migraine and tension headaches. The third way, yet to be proven, is by altering body perception.

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