Atypical Facial Pain
The term “atypical facial pain” has often been used to refer to any facial pain other than classic trigeminal neuralgia. However, this term more properly describes a type of deep burning, throbbing, or aching pain, usually confined to one side of the face but sometimes affecting both sides. It is usually constant but can have occasional brief, stabbing components. Unlike trigeminal neuralgia, there are no trigger zones. It occurs much more frequently in women than in men, and may occur following minor trauma or dental procedures.
The cause of atypical facial pain is unknown. However, in the majority of patients there is a marked degree of depression and anxiety which can contribute to worsening of the pain. Tricyclic antidepressants such as amitriptyline (Elavil) have been used to treat atypical facial pain, with complete relief in up to 80% of patients. The surgical treatment of atypical facial pain is controversial. Procedures which destroy parts of the nervous system are not indicated for treatment of this condition. Stimulation procedures such as deep brain stimulation or motor cortex stimulation may be somewhat effective, but should be reserved for patients who have failed to respond to an adequate trial of medication and who are actively participating in psychological treatment and counseling.
Therapy for Unmanageable Chronic Pain
Patients with chronic deafferentation or neuropathic pain who are resistant to previous medical and surgical therapies may benefit from a targeted form of neuromodulation surgery.
Cleveland Clinic’s Center for Neurological Restoration is one of the few centers worldwide to offer this procedure for unmanageable, disabling chronic pain. Pioneered in Japan and Europe, the surgery involves a small craniotomy implant procedure.
The next step is an inpatient trial involving subthreshold stimulation using varying parameters. The trial is considered successful if the patient has a consistent 50 percent reduction in pain. If successful, the second stage of the procedure – connection of the electrodes to a pulse generator in the upper chest just under the skin – follows.
Persistent Pain Following Spinal Surgery
Also called “failed back surgery syndrome” or “failed laminectomy syndrome”, continued chronic pain is common following spinal surgery. It is difficult to estimate how many patients develop persistent pain following spinal surgery, since patients undergo surgery for various indications. Some studies have suggested that as many as 90% of patients who have surgery for back pain alone, without nerve compression or spinal instability, will go on to develop chronic pain. The best treatment for this syndrome is thus education and prevention, since once surgery is done, it cannot be “undone.” However, even in many patients for whom surgery is clearly indicated, persistent pain can develop following both successful and unsuccessful back surgery.
There are many possible causes for chronic ongoing pain. Uncommonly, the original surgery may have failed to address the underlying problem of nerve compression. In these cases, repeat imaging will demonstrate the ongoing compression. Re-operation to address the problem is usually successful. In most patients, however, there are other causes of the pain which are more difficult to address.
Most patients with persistent pain following spinal surgery have components of both leg pain and back pain. Leg pain is usually due to compression or injury of the nerve roots, which originate from the spinal cord and leave the spinal column to form the major nerves of the leg, most commonly the sciatic nerve. Ongoing leg pain can have many causes, including longstanding nerve compression, manipulation or injury of the nerve during surgery, failure to address the original compression, re-herniation of a disc after successful disc surgery, arachnoiditis, and scar tissue. For most of these diagnoses, repeat surgery is not indicated, although disc re-herniation and ongoing compression can sometimes be successfully treated by re-operation. Surgical success decreases markedly with each operation, and the long-term success rate in patients who undergo 4 or more spinal operations at the same level has been estimated at less than 10%.
Nerve compression, injury, or irritation usually causes a specific type of pain called “neuropathic” pain. Neuropathic pain is often described as burning, tingling, electrical, or shooting. A number of medications can be effective in treating neuropathic pain. Anti-seizure medications such as gabapentin (Neurontin) are often highly effective, as are the tricyclic antidepressants, including amitriptyline (Elavil). In many patients, neuropathic pain can be treated medically. However, in patients who do not respond to medication, surgical options may be considered.
Neuropathic leg pain is often reduced by epidural spinal cord stimulation. This procedure is done under local anesthetic under light sedation. A needle is placed in the low back, and an insulated wire electrode is placed in the epidural space, similar to the placement of epidural catheters for anesthetic delivery. X-rays are used during the procedure to verify proper location of the electrode. The electrode has four metal contacts which deliver low-voltage, pulsed electricity to the spinal cord. When the spinal cord stimulation is activated, a sensation of tingling or warmth is produced in the leg. The electrode is manipulated until this area of tingling overlaps with the usual area of pain. The electrode is then fastened in place and an extension wire is brought out through the skin. The patient is then discharged with an external control unit, which allows the strength of the stimulation to be adjusted. After a one week trial period, the effectiveness of the spinal cord stimulation is assessed by surgeon and patient. If 50% or greater pain relief has been achieved, a pacemaker is inserted under the skin of the abdomen or in the gluteal region, and attached by an extension cable to the electrode. The system is self-contained and completely internal, with no external components. Programming of the spinal cord stimulation can be done remotely using a computer console or a small hand-held device. Approximately 70% of patients will have long term pain reduction of 50% or greater.
Persistent back pain is often more difficult to treat than leg pain. A structured program of therapy, exercise, and psychological counseling can sometimes be effective in achieving 50% or greater pain reduction. However, some patients can be treated with opioid medications such as morphine, fentanyl (Duragesic), hydrocodone (Vicodin), and oxycodone (Oxycontin) with good results. The dangers of long-term narcotic use include tolerance and dependence. Tolerance refers to the need for escalating doses in order to achieve the same degree of pain relief. Dependence on opioid medication has two components, a physical component and a psychological component. Patients who are maintained on opioids for long periods of time will develop withdrawal symptoms if the medication is discontinued abruptly. This is termed physical dependence. Psychological dependence is reflected in cravings for the drug or anxiety regarding obtaining the drug. Addiction can be defined as a maladaptive behavioral change whereby the patient loses control over the use of opioids, becomes preoccupied with their use despite adequate pain relief, and continues their use in the face of apparent adverse consequences. It is rare that patients treated with opioids develop addiction, unless they have a prior propensity toward addictive behavior.
In patients who are receiving good relief from opioids but have intolerable side effects, delivery of medication directly to the spinal cord can be considered. This is performed by implanting a programmable pump beneath the skin of the abdomen, attached to a small catheter that runs into the spinal fluid and delivers the medication continuously. The pump is refilled with medication with a needle every 1-3 months. The advantage to delivering opioid medications directly to the spinal cord is that the dose delivered to the brain is much less, avoiding drowsiness, confusion, and euphoria, but allowing good pain relief at the spinal levels where the nerves enter the spinal cord. Many new medications are being developed and tested which may allow greater control over the pain modulating areas in the spinal cord.
In all cases of persistent pain following spinal surgery, psychological counseling and support is vitally important. Anxiety and depression can worsen pain, which can then worsen anxiety and depression, causing a vicious cycle which can be difficult to escape. Both medical and surgical treatments are enhanced by active therapy, psychological support, and vocational pursuits.
Infection by the herpes zoster virus causes an inflammatory condition known as shingles, which commonly occurs on the chest or abdomen but can occur in nearly any location. The rash of a shingles infection occurs along the distribution of a single sensory nerve. Once the rash subsides, discoloration or scarring may remain. Pain can commonly occur, but it is usually short-lived, improving within 1 to 3 months. Pain persisting longer than 1 month is called post-herpetic neuralgia. It has been estimated to affect 10-15% of patients with shingles, although the incidence is much higher above age 60, approaching 50%. Fortunately, the pain resolves over the course of 6-12 months in the majority of cases. However, a few patients will develop severe pain which persists for longer periods or may be permanent. The cause is unknown, but seems to be related to damage to the nerve fibers caused by the virus.
Post-herpetic neuralgia can have both a steady, burning or aching component, as well as an intermittent, sudden, stabbing component. Both types of pain can occur spontaneously, or may be aggravated by light touch or contact with clothing. Some patients report abnormal sensations similar to itching or crawling. The pain can be quite severe.
Once post-herpetic neuralgia develops, it can be very difficult to treat. Some investigators suggest that the development of post-herpetic neuralgia can be prevented by giving amantadine hydrochloride at the onset of the shingles infection. Other preventative medications which may decrease the incidence of post-herpetic neuralgia are levodopa and adenosine monophosphate. Still other investigators have advocated aggressive early treatment of pain in the acute phase with opioid medications such as morphine, based on the hypothesis that reduction of pain impulses may prevent further sensitization of the pain circuits in the spinal cord and brain.
Tricyclic antidepressants such as amitriptyline (Elavil) can provide moderate to excellent pain relief in 50-70% of patients. Anti-seizure medications such as gabapentin (Neurontin) can be effective for treating the brief, stabbing components of the pain. Lidocaine patches applied to the skin have also shown some efficacy.
If medical treatment fails to relieve the pain of post-herpetic neuralgia, several surgical options are available. However, the results are generally disappointing and variable. Destruction of the spinal nerves or portions of the spinal cord have been effective in some cases, although in others the pain has been worsened or new numbness or weakness has been caused. Non-destructive procedures such as spinal cord stimulation, intraspinal drug delivery, and deep brain stimulation may occasionally be effective, and have the advantage of being reversible if they fail to provide effective relief. In general, treatment with medications is more effective than surgery for post-herpetic neuralgia, although surgery remains an option for selected patients who have failed all other treatments.
Post-Stroke Pain and Thalamic pain
A stroke is an injury to the brain due to interruption of the blood supply, causing destruction of a portion of brain tissue which can lead to weakness, numbness, paralysis, speech difficulties, confusion, or other problems. A small number of patients (less than 10%) will develop severe pain following a major or minor stroke. Post-stroke pain, also sometimes called thalamic pain or central pain, occurs most frequently following strokes on the right side of the brain, affecting the left side of the body. The pain usually develops after a period of time, although the time course is extremely variable, ranging from days to years.
Post-stroke pain has been described as burning, aching, or pricking in nature, although the character of the pain can be widely variable. The pain is usually constant and unrelenting, with a tendency to increase in intensity over time. It may involve face, arm, leg, trunk, or the entire half of the body. The pain may be worsened by movement, changes in temperature, or other unrelated stimuli. It is often accompanied by abnormal sensation in the affected body part.
A number of medical treatments have been tried for post-stroke pain, none of which have proven to be particularly effective. Tricyclic antidepressants such as amitriptyline (Elavil) are the only medications which have shown some efficacy in treating the constant component of the pain, although anti-seizure medications such as gabapentin (Neurontin) and carbamazepine (Tegretol) have shown some mild effectiveness in the treatment of brief, stabbing pains which can sometimes occur.
Surgical treatments for post-stroke pain have showed much more promise than medications. Deep brain stimulation has been shown to provide some measure of pain relief for at least 50% of patients, with some achieving excellent relief of pain. Motor cortex stimulation is a newer procedure which is now being used in the treatment of post-stroke pain. The results appear to be comparable to deep brain stimulation, with about 50% of patients achieving good pain relief and a smaller percentage achieving excellent or complete relief. The selection of deep brain stimulation versus motor cortex stimulation depends on the character and distribution of the pain, as well as the extent of the stroke and other factors. As with all chronic pain syndromes, psychological factors play a major role in the intensity of the pain. It is recommended that all patients with post-stroke pain consult with a psychologist specializing in the evaluation and treatment of chronic pain. Although post-stroke pain is a challenging problem, surgical procedures offer some hope for relief.