Can We Forget About Chronic Pain?

By Ann Marie Gaudon, PNN Columnist

I recently came across a clinical report which describe two patients with a lengthy history of chronic pain severe enough to warrant opiate therapy. Both patients experienced sudden memory loss and forgot about their pain – literally.

Central sensitization is a process known to occur in the spinal cord and brain where if short-term acute pain is allowed to persist, then changes occur within the central nervous system which can lead to chronic or intractable pain.

That’s what happened to me. I have a diagnosis of a visceral pain syndrome, as opposed to a progressive pain condition. I experienced one vicious organ assault and after more than 30 years of it being healed, I remain in pain.

Other patients who have experienced painful trauma may relive painful episodes that evoke recurring memories -- they experience their pain over and over again. That is a classic symptom of post-traumatic stress disorder (PTSD). Think of a war veteran or survivor of sexual violence.

Either way, neurophysiologic changes which relate to learning, memory and pain can result in a maladaptive learning process which leaves one in chronic pain. These intricacies happen outside of conscious awareness. We are not aware of or in control of this dysfunctional process while it is occurring within our brain and spinal cord circuits.

Here is an overview of the two patients discussed in the report:

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Patient #1

The first patient is a 47-year old female with complicated health problems. She had undergone multiple surgeries and treatment modalities for gastric ulcers, endometriosis, thyroid cancer, hypothyroidism, seizure disorder, malnutrition and chronic abdominal pain over 10 years.

Her pain was managed with high doses of opiate medications in various forms, including intravenous, transdermal and oral. During a complex 12-month hospital stay, she had at least five seizures and suffered memory loss so severe she could not remember her entire stay in the hospital.

She did eventually become fully alert and oriented to the present, but she no longer complained of her pain symptoms and no longer demonstrated a need for consistent pain medication.

Six months after discharge, the patient was living at home in stable condition and only occasionally using tramadol. She reported her symptoms as minimal and 1-2 on the pain scale. She still has no memory of many aspects of her long hospitalization.

Patient #2

A 57-year old male was described as a “highly functioning architect” with a 10-year history of low back and right extremity pain. He had undergone many unsuccessful treatments for pain, including surgery, and was being admitted to hospital to have an intrathecal pump surgically implanted for pain control. He was taking no less than nine medications for pain including high doses of opiate therapy.

Initially after the pump was placed, he reported having a partial reduction of pain in his leg. However, in the next six months he was requesting higher doses of intrathecal as well as oral opiates.

One month after this, the patient was in a minor motor vehicle accident where he did not lose consciousness, but inexplicably had partial memory loss. His physicians felt the accident was not the cause, as the memory loss symptoms occurred long afterward. The cause of the amnesia was unknown and tests including a brain MRI showed as normal.

The patient could not remember the names of his doctors, where he lived, what type of work he did, or why he had a pain pump implanted. He was weaned off opiates without any complaint of increased pain and subsequently had the pump removed at his request.

Eight months later, this patient was found minimally responsive in his home. It is not known what occurred, but there was a suspicion that he had fallen and incurred a head injury. The patient experienced profound memory loss, with no memory of who he was, his family members or his back pain.

His pain medications were discontinued with no complaint of pain, but he required placement in a long-term care home due to severe amnesia. Over the next two years, this patient regained partial memory, along with some back and leg pain. He has not requested or required opiate therapy.

Emotions, Pain and Memory

We know pain perception can be caused by nociceptive stimuli, yet we also know that emotional and psychological factors can increase our perception of pain. A complex play of nerve fibers which transmit messages to the brain and spinal cord suggest there is a relationship between emotions, pain and memory. The best evidence that memory plays a role in pain is that of phantom limb pain.

The two cases presented here suggest that memory may influence the perception of pain, and that amnesia can be accompanied by a loss of or significant reduction of pain in the absence of any physical factors.

Treatments that reduce “pain memories” in the brain and spinal cord, along with a focus on preventing pain to reduce or eliminate these memories, may someday have a more widespread role in the management of chronic pain. To have a treatment or ability to effectively erase a maladaptive pain memory leaves me with just three words:

Count me in.

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Ann Marie Gaudon is a registered social worker and psychotherapist in the Waterloo region of Ontario, Canada with a specialty in chronic pain management. 

Ann Marie has been a chronic pain patient for over 30 years and works part-time as her health allows. For more information about her counseling services, visit her website.

This column is for informational purposes only and represents the author’s opinions alone. It does not inherently express or reflect the views, opinions and/or positions of Pain News Network.

Does Chronic Pain Affect Memory?

By Ann Marie Gaudon, PNN Columnist

Pain is a complex experience. It not only affects us biologically, but we also experience it cognitively and emotionally. Does it affect our memory? You bet it does.

Chronic pain patients often complain of memory problems and there are numerous studies which confirm these challenges are indeed a reality.

Twenty-four studies evaluating working memory (WM) and/or long-term memory (LTM) in chronic pain groups and control groups were reviewed last year by French researchers. WM was defined as the processing and manipulation of information within a short period of time (a few seconds), while LTM involved the “storage” of knowledge and memories over a long period of time.

Concentration and memory deficits on a daily basis were the most frequently reported cognitive difficulties. Memory complaints included forgetfulness and problems performing everyday tasks and conversations.

Emotional distress common to pain patients, such as depression, anxiety and rumination (the inability to divert attention away from pain), was also found to play an important role in memory difficulties.

One study compared two groups of pain patients who had minor or major memory complaints. Between the two, no significant differences were found with regard to age, gender, education level, marital status, medication use, long-term pain or pain intensity.

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However, patients in the major memory complaint group suffered from emotional distress to a significantly greater degree. They also reported a lack of family support and discontent with their social and sexual lives. These were noted as additional daily sources of suffering for this group.

Adding to potential negative effects on memory were comorbidities which many pain syndromes share. Conditions such as depression, anxiety, sleep disturbances, and chronic fatigue could alone or combined affect memory. A major concern expressed was the need to disentangle pain-related cognitive effects from those resulting from these comorbidities.

Medications and Memory

The review really became interesting when it came to medication, because researchers found contradictory results. One European study reported that opioids exerted a negative effect on working memory -- finding a clear association between higher levels of analgesics and perceived memory dysfunction in chronic back pain patients. Some studies confirmed that medication can have a negative effect on memory, but others showed improvements in memory following analgesic treatment. That suggests that effective pain relief may also reverse pain-induced memory impairment.

The researchers concluded it was unclear whether analgesic medications are beneficial or detrimental, because both scenarios were reported.

Age was also identified as an important factor in the relationship between chronic pain and memory, but not in the way you may think. Surprisingly, it was shown that an increase in age did not additionally affect memory performance.

One study reported that gender and age significantly affected memory decline in those suffering from chronic migraine headaches. Cognitive decline in migraineurs was greater among younger individuals, and females showed greater decline during headache intervals than males. It was acknowledged that gender as a factor in pain-related experience is poorly investigated.

Like all reviews, this one has its limitations. There was a “large heterogeneity” of tests within the 24 studies. This diversity of tests did not allow for a suggestion of which memory processes were altered by chronic pain itself. The study populations were also heterogeneous regarding pain etiologies and an assessment of the intensity of pain was not performed.

Studies which included a mix of chronic pain disorders did not provide data on whether specific memory impairments were more frequently observed in specific disorders. The authors suggest there is a need for comparative studies across pain-related disorders in order to determine whether impairments are pain-related or a consequence of other pathophysiological features.

These numerous studies confirmed the memory decline that is often reported by chronic pain patients. Even if these effects are mild, the impact on quality of life could be substantial as they may indeed worsen suffering including depression, anxiety, and limitations on activity.

Researchers suggested that examining memory function should be part of the clinical assessment of chronic pain patients. The spectrum of cognitive difficulties must become acknowledged and understood in order to find ways to overcome them.

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Ann Marie Gaudon is a registered social worker and psychotherapist in the Waterloo region of Ontario, Canada with a specialty in chronic pain management.  She has been a chronic pain patient for over 30 years and works part-time as her health allows. For more information about Ann Marie's counseling services, visit her website.

The information in this column should not be considered as professional medical advice, diagnosis or treatment. It is for informational purposes only and represents the author’s opinions alone. It does not inherently express or reflect the views, opinions and/or positions of Pain News Network.