Case 1
A 52 year old male presents with the complaint of pain radiating from his lower back to his right lower extremity. His past medical history is not significant for any chronic medical problems. Eighteen months ago after lifting a box of heavy tools at his home, he experienced severe pain in his lower back which radiated to his right foot. He was found to have a large herniated disk at the L5-S1 level with severe compression of the right S1 nerve root. He developed weakness of ankle flexion and hip extension as well as loss of sensation in the S1 dermatome and loss of his right ankle reflex, and after failing to improve following conservative therapy he underwent a lumbar laminectomy at the L5-S1 level. While the surgery was successful in that he regained full strength in his right lower extremity, the pain in his lower back radiating to his right foot actually intensified within the immediate post-operative period.
Multiple post-op diagnostic studies including MRI and EMG/NCV confirmed that there was no evidence of direct compression of the S1 nerve root nor was there recurrence of a herniated disk; however, the EMG/NCV suggested changes consistent with a chronic right S1 radiculopathy. Prior to this visit, the patient was seen by an interventional pain specialist who performed several selective nerve root injections without benefit. The patient has been advised to undergo a spinal stimulator trial but declined as he does not want to pursue any additional invasive treatment.
The patient is experiencing neuropathic low back pain. Neuropathic low back pain can be considered from a structural standpoint, distinguishing among processes that originate as the result of clear nerve compression or injury to those in which the neural hyperexcitability is associated with chronic inflammation to those in which there may be central nervous system changes facilitating the pain. When considering treatment for this type of neuropathic pain, it must be emphasized that there are limitations due to a lack of randomized controlled trials. Often, multimodal therapeutic approaches combing medical, interventional and non-medical approaches are required to maximize pain relief for such patients.
Case 2
A 68 year old female presents complaining of burning pain in her feet. Her past medical history is notable for hypertension, osteoporosis and onset of diabetes mellitus type 2 six years ago. Current medications include metformin 500 mg twice daily, lisinopril 10 mg daily and alendronate 70 mg weekly. For the past eight weeks, she has been complaining of numbness in her feet but also of burning pain. She states that whenever anything touches her feet, even her bed sheet or a towel after bathing, the pain increases. On examination, notable findings include absent ankle reflexes bilaterally, diminished pin prick sensation to the calves bilaterally and “discomfort” when her feet are touched lightly with the soft end of a Q-tip. Her routine laboratory studies do not suggest any new abnormalities and the remainder of her examination is unchanged. Based on the clinical presentation, she likely has developed painful diabetic neuropathy (PDN).
Although EMG/NCV studies can be useful in confirming the diagnosis of PDN, a normal study does not rule out the condition. EMG/NCV studies primarily measure the electrical activity of myelinated fibers and PDN may predominantly affect unmyelinated fibers; thus, the study may be normal in someone who is not “normal” but in fact has altered pain signaling due to damaged unmyelinated nerve fibers. Of interest is the emerging use of skin biopsies (3mm punch) as a diagnostic tool in selected patients. In addition to nonpharmacological therapies including, for example, maximizing blood glucose control, proper foot care/hygiene and regular exercise, multiple medical therapies have been shown to be helpful in the treatment of PDN.
In the United States, two pharmacologic agents are FDA approved specifically to treat this condition: duloxetine and pregabalin. Other agents which may be considered include tricyclic antidepressants, topical lidocaine, venlafaxine, and opioids. Not infrequently, patients may experience maximal relief when two or more agents with different mechanisms of action are combined.
Case 3
An 73 year old male with a past medical history of congestive cardiomyopathy, hypertension and degenerative joint disease complains of pain that originates in his left lower back and radiates anteriorly into the groin. When asked to characterize the pain, he states that it is always present and has a deep aching, burning or tingling quality. Warmth exacerbates the ache so it is exquisitely painful for him to bathe; he is unable to wear trousers due to the pain, and able to tolerate only loose-fitting sweat pants without underwear.
He describes the pain as 7 on a scale of 0 – 10, and states that the discomfort is causing him to lose sleep. Nothing relieves the pain, although application of topical analgesic cream does lessen it for a short while. Although he is able to ambulate without assistance, his wife says that he can’t do any of his usual chores around the house due to the pain. She adds that she recognizes that the pain is in excess of her husband’s usual arthritis pain, and confides that it is causing him to be irritable and short with her.
Physical exam is unremarkable with the exception of scattered hyper-pigmented and scarred areas across the left lumbo-sacral area involving the L3 to L5 dermatomes with extension of the scarring anteriorly to the lower abdomen. The area is extremely sensitive to light touch and pain is elicited beyond the margins of the post-inflammatory area of hyperpigmentation. In addition to experiencing burning, aching pain at the dermatomal sites of the resolved shingles rash, the patient also has numbness and tingling extending in a wide arc over the lower thoraco-lumbar and anterior pelvic regions making it difficult to dress, bathe, sit, or lie down comfortably. The phenomenon of dysesthesia extending beyond the area of the rash site is characteristic of post-herpetic neuralgia.
This gentleman had a “very bad” case of shingles approximately three months ago. The pain from the rash had lessened for a few weeks during the course of treatments prescribed by an emergency department physician, but returned with increasing severity over the prior few weeks. He had received a seven-day course of famciclovir 500 mg three times a day, methylprednisolone tapering dose pack and a prescription for oxycodone/APAP 5/325 mg to be taken as needed in the emergency department. The latter made him nauseous; he stopped taking it after the first day and instead has been taking over-the-counter ibuprofen for the pain.
The patient is experiencing post-herpetic neuralgia (PHN), the most common complication of herpes zoster infection. Herpes zoster represents the reactivation of varicella zoster virus (VZV), a viral illness with two distinct stages. Following primary VZV infection (“varicella” or “chickenpox”), the virus becomes dormant in the dorsal root ganglia to reactivate at some later time as herpes zoster, or shingles. Waning cell mediated immunity with advancing age is the biggest risk factor for development of shingles, although cellular immunosuppression due to HIV/AIDs, hematologic malignancy, bone marrow transplantation, systemic lupus erythematosis and immunosuppressive treatments have also been implicated.
Herpes zoster can occur at any age, but is most severe in the elderly, who not coincidentally (due to increased severity and complications) have the highest rates of hospitalization during acute herpes zoster infection and are most at risk for potentially life-threatening or disabling complications. Incidence and severity of zoster increase with advancing age. Of the estimated 1 million cases per year, approximately 0.74 to 5.09 per 1000 persons per year in immunocompetent adults younger than age 60 and 10.79 to 11.50 per 1000 persons per year in immunocompetent adults age 60 and older are affected. Approximately 40% to 50% of cases of shingles occur in individuals aged sixty or older, and approximately 50% of individuals 85 years of age will have experienced a case. PHN affects as many as 65% of patients aged 60 or older; since about 1 in 3 persons will develop zoster, the risk of developing PHN is significant.
Definitions of PHN vary, but in general it represents any pain persisting after resolution of the rash. PHN is, unfortunately, a common cause of NP in clinical practice, and herpes zoster provides an instructive model of how infection (in this case varicella zoster virus) can cause significant nerve damage resulting in NP.
The Joint Meeting of the Drug Safety and Risk Management Advisory Committee with the Anesthetic and Life Support Drugs Advisory Committee and the Nonprescription Drugs Advisory Committee, which met June 29-30, 2009 to discuss steps to reduce acetaminophen-related overdoses and associated liver toxicity...
Bridget Martell et al presented an ambitious, systematic review of the effectiveness of opioid therapy in the treatment of chronic back pain.
Patient J.L. presented to pain management/neurology with complaints of low back pain and radiating right greater than left buttocks pain. Patient also complained of radiating right antero-lateral thigh pain, which occasionally radiated to antero-lateral lower leg.