Patterns of Common Pain Syndromes
Pain Management, Chapter 6, 50-56
Chapter outline
- Temporal Pattern 51
- Spatial Pattern 51
- Symptomatic/Anatomic/Etiologic Diagnostic Approach to Pain Problems 51
- Referred Pain Patterns 52
- Spinal Pain Patterns 52
- Vertebral Pain Syndromes 52
- Spinal Radiculopathies 55
- Cervical Facet Syndrome 55
- Lumbar Radiculopathy 55
- Lumbar Facet Syndrome 56
- Lumbar Spondylolisthesis 56
- Lumbar Spinal Stenosis 56
- Arachnoiditis 56
Discussions of patterns of pain syndromes form a large portion of this comprehensive book. The text is divided into sections on generalized pain syndromes, including acute pain syndromes, neuropathic pain syndromes, malignant pain syndromes, pain of dermatologic origin, and pain of musculoskeletal origin, and regional pain syndromes, encompassing virtually every part of the body. This chapter does not reiterate material that is discussed in detail in appropriate chapters, but rather outlines the general features and underlying principles of patterns in pain-producing syndromes.
Pain is defined by the International Association for the Study of Pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. Several types of pain are recognized.
Nociceptive pain is caused by the ongoing activation of nociceptors (pain receptors) in response to noxious or potentially noxious stimuli. It may be cutaneous, deep somatic, or visceral. It is associated with “proper functioning” of the nervous system, and generally the severity of the pain corresponds closely to the intensity of the stimulus. Although its characteristics may vary with the part of the body involved, the tissues under attack, or the intensity, acuteness, or chronicity of the process, nociceptive pain is familiar, expected, recognizable, and attributable to a source. In short, “it makes sense,” or, in modern parlance, it “computes.” Many different pain types and patterns emerge.
Neuropathic pain is caused by aberrant signal processing in the peripheral or central nervous system and reflects nervous system damage or dysfunction. It has an unexpected aspect, detached from an obvious stimulus intensity or putative tissue damage. It is characterized by burning, tingling, or shooting sensations, which may be spontaneous or evoked, steady, or intermittent. This pain may be associated with other clear-cut neurologic phenomena, such as sensory loss, allodynia (pain elicited by a non-noxious stimulus, such as clothing, air movement, touch, or an ordinarily nonpainful cold or warm stimulus), or hyperalgesia (exaggerated painful response to a mildly noxious, mechanical, or thermal stimulus). Common sources of neuropathic pain include trauma, metabolic disease (e.g., diabetes mellitus), infection (e.g., herpes zoster), tumors, toxins, side effects of medications (especially chemotherapeutic and antiviral agents used to treat human immunodeficiency virus [HIV] infections), and primary neurologic diseases. Central pain may arise in the setting of stroke, tumor, spinal cord injury, or multiple sclerosis. Neuropathic pain has the characteristic of unfamiliarity, is often inexplicable, is hard to believe (even for the experienced observer), and, in short, “doesn't compute.”
Another caveat concerns “what is common.” This depends on the patient or physician setting (e.g., whether it is an emergency department, cancer center, or pain clinic). Physician specialty and interests also play an important role. The painful manifestations of rheumatoid arthritis or multiple sclerosis and painful peripheral neuropathies are rarely seen at an average pain clinic, which is more concerned with problems of the axial spine, complex regional pain syndrome, and postherpetic neuralgia. Conditions seen on a daily basis by podiatrists, rheumatologists, or orthopedists may be terra incognita to the pain physician.
Several universals are noted in pain patterns. Pain patterns have the following: a temporal and spatial distribution; characteristic pain types (e.g., burning, tearing, gnawing, deep, superficial); and often associated medical diagnoses, other symptoms, and other features that offer important clues to the diagnosis and management. One of the most commonly overlooked features of pain patterns is the occurrence of a secondary or tertiary type of pain pattern. This feature is clearly apparent in radiculopathies, which often manifest as a sharp (and sharply delineated) pain (“epicritic pain”) and tend to obscure a deeper, less well-delineated gnawing-type pain (“protopathic pain”). The two types of pain originate in the same relative area of the body (e.g., cervical or lumbar region) and often at the same axial spinal level (e.g., C6-7 or L4-5), but stem from different tissues or structures (e.g., nerve root versus vertebral body or facet joints). Careful inquiry for a secondary or tertiary type of pain (rarely volunteered by the patient) produces a much greater understanding of the pathologic process involved.
Temporal Pattern
It is a well-shown principle of pain management that the temporal pattern of the pain complaint is derived largely from the patient's history and sheds light on the possible cause of the problem. A relentlessly progressive course suggests serious underlying disease and warrants further inquiry (additional comprehensive history, physical examination, appropriate associated laboratory studies, and imaging techniques) for malignancy or infection. A rapid onset and rapid relief of pain are characteristic of neuropathies or neuralgia (e.g., trigeminal neuralgia).
Spatial Pattern
The spatial distribution of the pain in conjunction with physical examination, laboratory tests, and imaging procedures suggests the localization of the problem (e.g., cervical radiculopathy or lumbosacral plexus disease) and tends to limit the diagnostic possibilities. All physicians with even a brief exposure to pain problems recognize the syndromic approach to pain management. This approach is familiar in the example of cervical radiculopathy, with neck pain accompanied by radiation in a dermatopic nerve root distribution down into the thumb, index finger, or both. More detailed questioning may reveal a deep gnawing pain extending into the root of the neck, shoulder, or intrascapular area. This approach may serve well if alternative situations, such as referred pain (e.g., from a distal nerve lesion such as an ulnar nerve palsy or from an internal viscus) and the possibility of a tumor rather than a cervical disk disorder or spondylosis, are not forgotten.
Symptomatic/Anatomic/Etiologic Diagnostic Approach to Pain Problems
It is good practice to form a symptomatic/anatomic/etiologic diagnosis for each pain problem. This practice eliminates jumping to a syndromic conclusion and serves as framework for an orderly approach to the problem. This approach is demonstrated by the following cases.
Case 1
A 36-year-old woman developed diffuse neck pain without an antecedent history of illness or injury. The pain was deep and gnawing and was accompanied by sharp pain down the radial aspect of her arm and forearm to the thumb, index, and middle fingers. It was accompanied by a deep, boring (worse at night) intrascapular pain and mild weakness of the right biceps muscle. She had mild numbness of the thumb. Examination revealed limited range of motion of the cervical spine to the right and a right Spurling sign (pain reproduced by extension and lateral rotation to the right). She had mild weakness of the right biceps and brachialis, a diminished right biceps reflex, and hyperesthesia in the right C6 distribution.
The symptomatic diagnosis in this case is pain in the neck and down the right arm with mild C6 motor and sensory signs. This diagnosis is arrived at by a combination of the history and the physical examination. Syndromically, it could be referred to as “cervical radiculopathy without evidence of myelopathy.” For reasons that become clear in the next case presentation, the syndromic diagnosis should be made cautiously. The anatomic diagnosis in this case is C6 radiculopathy as a result of physical examination findings. The anatomic diagnosis may be augmented by electromyography, which is an extension of physical examination because it is based on physiologic examination of nerve, nerve root, and muscle. It is not based on imaging technique at this point because imaging technique may give irrelevant information and always requires clinical correlation. The etiologic diagnosis is cervical radiculopathy resulting from herniated nucleus pulposus at C5-6, based on magnetic resonance imaging (MRI) of the cervical spine that showed a herniated disk at C5-6 correlated with the history and physical examination and not negated by any more plausible diagnosis. This may seem a convoluted method of diagnosis, but its merits are better illustrated by the following cases.
Case 2
A 56-year-old, right-handed man developed pain in the right supraclavicular region with associated neck pain of boring quality, worse at night, with radiation of fairly sharp pain down the ulnar border of the arm. Neck turning and shoulder movements exacerbated the pain, which was particularly bad at night. Examination revealed that the right pupil was slightly smaller than the left, but fully reactive. The patient had some weakness of the intrinsic hand muscles and hyperesthesia along the ulnar border of the right forearm. No reflex changes were noted. MRI revealed diffuse ridging at all levels, but worst at C7-T1. No long tract signs (signs of spinal cord involvement) were noted.
Syndromic diagnosis would be lower cervical radiculopathy secondary to spondylosis. This diagnosis conceivably could lead to inappropriate therapeutic measures. The symptomatic diagnosis is neck, shoulder, and arm pain in a lower cervical distribution. The anatomic diagnosis is C8-T1 root or brachial plexus involvement (>90% of all cervical nerve root disorders involve the C5-6 or C6-7 levels emanating from the C6 or the C7 nerve roots). The etiologic differential diagnosis includes involvement of the brachial plexus by Pancoast's tumor of the lung, C8-T1 disease or acute brachial plexitis (Parsonage-Turner syndrome), or primary tumor of the nerve roots (meningioma or neurofibroma). In this case, a chest radiograph and computed tomography (CT) scan revealed a malignant tumor of the right upper lobe of the lung, and MRI of the brachial plexus showed erosion by the tumor. In this case, keeping an open mind and using the symptomatic/anatomic/etiologic approach averted a significant error in diagnosis and treatment.
Case 3
A 64-year-old man presented with sharp and aching pain in the left shoulder blade, neck, and elbow. The sharp pain was referred from the elbow into the forearm, and the aching pain in the elbow (occasionally) was referred to the neck and the forearm, related to exertion, although the association was unclear. Some association (again unclear) existed with flexion-extension of the left elbow that produced the sharp and the aching pain. The patient had intermittent numbness of the ulnar portion of the left hand and forearm, as well as weakness of the left abductor digiti, first dorsal interosseous muscle, and adductor pollicis brevis. No cranial nerve, long tract, or sphincteric signs were observed.
In this case, the symptomatic diagnosis is sharp and aching elbow pain and shoulder and forearm pain potentially related to exertion or flexion-extension, or both, of the elbow. The anatomic diagnosis is unclear and requires further elucidation by electromyography for possible ulnar neuropathy at the elbow, brachial plexus lesion, and a cardiology workup for atypical angina pectoris. The anatomic differential diagnosis includes such diverse possibilities as visceral (cardiac or pulmonary), musculoskeletal (scapulocostal syndrome or other chest wall syndrome), or peripheral nervous system (ulnar entrapment at the elbow with radiation to the chest wall or lower brachial plexus or cervical spine pathology) conditions. The etiologic diagnosis is in doubt at this point because numerous possibilities largely depend on the anatomic location of the problem.
Any attempt at syndromic diagnosis is fraught with hazard because it forces the examiner prematurely into identifying an organ system as the cause of the pain with little or no evidence to support any one possibility. The symptomatic/anatomic/etiologic approach serves as a “holding area” while each of the diagnostic possibilities is explored, without the examiner's having to jump to conclusions.
The symptomatic diagnosis seems self-evident, although the tendency is to try to fit it into a defined syndrome, such as cervical radiculopathy, complex regional pain syndrome, or migraine, in clear-cut circumstances. The anatomic diagnosis requires careful analysis of findings from physical examination, electromyography (when applicable), and imaging techniques. The physical examination and imaging findings must be concordant (match), and in case of a discrepancy, especially in spinal imaging in which abnormalities abound in asymptomatic patients, greater weight must be given to the physical examination findings, especially when they explain the clinical history. The etiologic diagnosis should include, at least preliminarily, a checklist of all possible types of pathologic processes. It is useful to review the list in Table 6.1 or at least give it brief consideration no matter how obvious the apparent cause may be. The putative anatomic site may be subdivided as shown in Table 6.2 .
Table 6.1
Partial List of Etiologic Causes of Pain
| Etiology | Examples |
|---|---|
| Vascular | Claudication, hemorrhage, space-occupying vascular malformations impinging on pain-sensitive structures |
| Tumor | Primary (e.g., meningioma or neurofibroma) and metastatic |
| Osseous | Primary bone disorders (e.g., Paget's disease, fibrous dysplasia, leontiasis ossea), DISH syndrome, focal spinal overgrowth (ridging) |
| Degenerative | Various arthritides, degenerative spine disease (spondylosis, spinal stenosis, spondylolisthesis, degenerated intervertebral disks) |
| Trauma | Herniated intervertebral disks, compression fractures, microtrauma |
| Metabolic | Diabetes mellitus, thyroid disorders, parathyroid disorders |
| Infectious | HIV infection, viral, bacterial, fungal, rickettsial infections |
| Collagen vascular disorders | Rheumatoid arthritis, systemic lupus erythematosus, polymyalgia rheumatica, temporal arteritis |
| Toxic | Exogenous and endogenous toxicities |
| Psychiatric | Substance abuse, depression, psychosis, personality disorders |
DISH, disseminated idiopathic skeletal hyperostosis; HIV, human immunodeficiency virus.
Table 6.2
Possible Generalized Sites of Anatomic Pathology Causing Pain
| Skin |
| Subcutaneous tissues, including fat and connective tissue |
| Ligaments and tendons |
| Skeletal muscles |
| Nerves, nerve roots, and plexus |
| Central nervous system structures, including spinal cord |
| Vascular structures, including arteries and veins |
| Lymphatics |
| Viscera |
Referred Pain Patterns
Physicians become familiar with the patterns of intrathoracic and intra-abdominal pain referral from internal viscera in the earliest years of training in clinical medicine. Referral patterns are particularly well discussed and illustrated in Wiener's classic text. A potential pitfall in referred pain diagnosis is the less well recognized referral of myofascial pain (e.g., referral of pain from the levator scapulae to the chest wall simulating angina or cholecystitis). So-called trigger points frequently simulate the pain of internal organs, thus raising the possibility of misdiagnosis and mistreatment. The concept of trigger point referral is most closely associated with Simons and Travell, who wrote the classic two-volume work on pain referral patterns. Volume 1 addresses referral patterns in the upper half of body (head, neck, thorax, and abdomen), and volume 2 addresses the lower extremities.
Spinal Pain Patterns
Vertebral Pain Syndromes
Vertebral pain tends to be deep and boring and present at rest. When associated with an aggressive process, the pain tends to increase stepwise and may spread to a radicular distribution, which may be “girdling” if it is in the abdomen or thorax. Jarring, movement, or percussion may exacerbate the pain. Although the pain characteristics may vary from condition to condition and from individual to individual, the presence at rest is highly suggestive and clearly different from radiculopathies, which tend to be ameliorated by rest and recumbency.
Spinal Radiculopathies
The pain of spinal radiculopathies tends to be quite sharp and well delineated, with the proviso that patients often have an associated deep, gnawing pain that is usually more proximal and less well defined than the sharp pain. This pain is attributable to irritation of nonradicular structures, such as bones and tendinous attachments, and follows a sclerotogenous pattern ( Fig. 6.1 ). Radicular pain usually follows well-understood and familiar patterns. , Pain distribution, sensory changes, motor weakness, and reflex changes in the cervical region are summarized in Table 6.3 , and changes corresponding to the lumbar region are summarized in Table 6.4 . Clinical syndromes associated with cervical spondylosis include acute stiff neck, radiculopathy, myelopathy, myeloradiculopathy, vertebrobasilar insufficiency, cervicogenic headache, and Barre-Lieou syndrome (cervical sympathetic syndrome).
Sclerotogenous pain pathways.
This illustration is useful for pinpointing referred sclerotogenous pain from spinal levels C1 through S3.
(From Clinical Charts & Supplies, Beverly, Mass.)
Table 6.3
Characteristics of Cervical Radicular Pain
| Cervical Root | Pain | Sensory Changes | Weakness | Reflex Changes |
|---|---|---|---|---|
| C5 | Neck, shoulder, anterolateral arm | Numbness in deltoid area | Deltoid and biceps | Biceps reflex |
| C6 | Neck, shoulder, lateral aspect of arm | Dorsolateral aspect of thumb and index finger | Biceps, wrist extensors, pollicis longus | Brachioradialis reflex |
| C7 | Neck, shoulder, lateral aspect of arm, dorsal forearm | Index and middle finger, dorsum of hand | Triceps | Triceps reflex |
Table 6.4
Characteristics of Lumbar Radicular Pain
| Lumbar Root | Pain | Sensory Changes | Weakness | Reflex Changes |
|---|---|---|---|---|
| L4 | Back, shin, thigh, leg | Shin numbness | Ankle dorsiflexors | Knee |
| L5 | Back, posterior thigh, leg | Numbness at top of foot and first web space | Extensor hallucis longus | None |
| S1 | Back, posterior calf, leg | Numbness at lateral aspect of foot | Gastrocnemius and soleus | Ankle jerk |
Cervical Facet Syndrome
Cervical facet syndrome is a syndrome of head, neck, shoulder, and proximal upper extremity pain largely in a nondermatomal distribution. The pain is usually dull and ill defined; it is worsened by flexion, extension, and lateral flexion of the neck (unilateral or bilateral) and is unaccompanied by motor or sensory deficits. Referral patterns are presented in Figure 6.2 .
Pain referral patterns from lumbar L4-5 and L5-S1 facet joint injections.
On the left are areas of pain drawn by asymptomatic subjects following injection of hypertonic saline into the facet joints. On the right are areas of pain drawn by patients with chronic back and leg pain who had similar injections. The different methods of shading indicate different patients.
(Redrawn from Renfrew DL. Facet joint procedures. In Atlas of spine injection , Philadelphia, 2004, Saunders, 73.)
Lumbar Radiculopathy
Patients complain of pain, numbness, tingling, and paresthesias in the appropriate nerve root distribution. The pain may be sharp and lancinating, but it is accompanied by a more vaguely, localized, proximally distributed sclerotogenous pain. Relative contributions of dorsal and ventral roots influence the character of the pain, and the ventral root pain is often duller and less well localized as a result of the predominately motor distribution. Involvement of the sinuvertebral nerve (recurrent nerve of Luschka) ensures at least some painful involvement of the axial structures, whereas a laterally placed process may result in pain purely localized to the limb and confusing because of the absence of the axial pain usually present in radiculopathies.
Lumbar Facet Syndrome
Patients usually are more than 65 years old, and the pain, which is less well localized than radicular pain, is deeper and duller. The pain is exacerbated by standing or lumbar extension and is improved by sitting and forward flexion. Pain is not exacerbated by coughing or other Valsalva-related maneuvers, it may be referred to the buttocks or ipsilateral thigh, and it generally presents in a more proximal distribution than radicular pain.
Lumbar Spondylolisthesis
Dull or sharp back pain is exacerbated with lifting, twisting, or bending. Patients often complain about a “catch” in their back. Rising from a sitting to standing position often reproduces the pain.
Lumbar Spinal Stenosis
Pseudoclaudication of the lower extremities is the characteristic pattern. Multiple roots are typically involved. The pain may disappear with spinal flexion (e.g., riding a stationary bicycle), but it results in fatigue with prolonged walking or standing ( Table 6.5 ). Pain is characteristically present in the calf, and it simulates vascular claudication. Pain, numbness, and weakness are seen in the affected segments. Muscle spasms and vague pains are commonly seen, including (paradoxically) pains in the intrascapular region.
Table 6.5
Spinal Stenosis versus Disk Protrusion (Radiculopathy)
| Spinal Stenosis | Disk Protrusion (Radiculopathy) | |
|---|---|---|
| Pain pattern | Insidious, less well localized, duller Worse with walking or standing Worse with extension | Acute, sharper, better localized Worse with sitting Worse with flexion |
| Age at onset (yr) | Most commonly 30–50 | Most commonly >60 |
| Response to conservative therapy (%) | 50 | >90 |
Arachnoiditis
Arachnoiditis is characterized by pain (generally duller and less well defined than radiculopathy, but may be severe and excruciating), numbness, tingling, paresthesias, and weakness, often in multiple nerve roots. Muscle spasm in the lumbar region with referral into the buttocks is common. Bladder and bowel symptoms are more frequent than expected with radiculopathy.
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