14.1 Myofascial Pain Syndrome
This condition is a regional musculoskeletal pain disorder which stems from the lack of obvious organic findings and characterized by tender trigger points in taut bands of muscle that produce pain in a characteristic reference zone.
14.1.1 Diagnostic clinical criteria
Pain complaint or altered sensation in the expected distribution of referred pain from a myofascial trigger point.
Taut band palpable in an accessible muscle
Exquisite spot tenderness at one point along the length of the taut band
Reproduction of clinical pain complaint, or altered sensation, by pressure on the tender spot.
Elicitation of a local twitch response by transverse snapping
Palpation at the tender spot or by needle insertion into the tender spot in the taut band
Pain alleviated by elongating (stretching) the muscle or by injecting the tender spot
14.1.3 Differential diagnosis
Mixed tension-vascular headaches: Associated with trigger points in the sternomastoid, suboccipital, temporalis, posterior cervical, and scalene muscles.
Thoracic outlet syndrome: Associated with trigger points in the scalene and pectoralis minor muscles.
Temporomandibular joint (TMJ) dysfunction: These conditions are often primarily myofascial in origin with particular trigger point involvement of the temporalis, masseter, and pterygoid muscles.
Piriformis muscle syndrome: Pseudosciatica with entrapment of the sciatic nerve by the involvement of the piriformis muscle and the trigger points identified within this muscle.
Gerwin RD. Differential diagnosis of myofascial pain syndrome and fibromyalgia. J Musculoskeletal Pain 1999;7:209–215 (The Haworth Medical Press)
Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual. Vol. 1. 2nd ed. Baltimore: Williams and Wilins; 1998
Borg-Stein J, Simons DG. Focused review: myofascial pain. Arch Phys Med Rehabil 2002;83(3, Suppl 1):S40–S47, S48–S49
14.2 Fibromyalgia Syndrome
The American College of Rheumatology (ACR) set two criteria for the diagnosis of fibromyalgia syndrome (FMS). (1) chronic (i.e., persisting longer than 3 months) widespread pain, dull diffuse aching modulated by several factors, including weather changes, exercise, and stress. (2) Multiple localized areas of tenderness (trigger points), generally defined as 11 of 18 specific tender points of precisely determined location on examination. Patients with FMS report numerous additional—apart from pain—complaints: most common and more characteristic occur in over 75% of patients include fatigue, nonrestorative sleep pattern, and morning stiffness. Less common features (approximately 25% of cases) are irritable bowel syndrome, Raynaud’s phenomenon, headache, subjective swelling, nondermatomal paresthesia. In addition, people with FMS often have neurotic, functional symptoms, including depression (20–80%), anxiety states (13–63%), emotional instability, and personality disorders.
The specific cause of FMS remains unknown; however, a number of events are known to be associated with this condition. These include trauma (particularly head and/or neck injury from motor vehicle accidents), recent infection, and stress. Sleep disturbances also play an important role in the pathology. FMS patients lack stage 4, non-REM (or slow-wave) sleep. Serotonin is considered the neurotransmitter that mediates slow-wave sleep. Inhibition of serotonin (or its precursor tryptophan) is associated with a decrease in slow-wave sleep and an increase in the somatic symptoms.
14.2.1 Diagnostic criteria of fibromyalgia syndrome
If both the criteria are fulfilled, FMS is confirmed. Other disease does not exclude FMS (sensitivity 95% and specificity 84%).
14.2.2 Differential diagnosis of fibromyalgia syndrome
Common features: depression and anxiety
But: In psychiatric disorders there are less somatic, functional symptoms and no tender points in clinical examination.
Common features: Myalgia and arthralgia, dry mouth, dry eyes, Raynaud’s phenomenon, paresthesia, mild psychological disturbances (e.g., mild depression).
But: In Sjogren syndrome positive Schirmer test, > antinuclear antibodies (ANA), and anti-La/Ro antibodies, abnormal salivary glands biopsies.
Predominate in both young and middle-aged female, widespread, nonspecific arthralgia and myalgia, Raynaud’s-like peripheral acrocyanosis, debilitating fatigue, high sensitivity to light and noise, and menstrual irregularities.
But: ANA not elevated > 1:640, no anti-dsDNS antibodies
Common features: Arthralgia in hands and feet, prolonged morning stiffness, subjective puffiness of the hands and fingers, paresthesia in the fingers suggestive of carpal tunnel syndrome, Sicca syndrome (dry eyes, dry mouth). But: Elevated erythrocyte sedimentation rate (ESR), C-reactive proteins (CRP), anti-cyclic citrullinated peptide (CCP), and rheumatoid factor (RF).
Out of FMS patients aged more than 60 years, 6% have previously been misdiagnosed as having PMR.
But: Inflammatory markers (ESR and CRP) are frequently elevated. The ESR, however, can be normal in 6% to 20% of patients with PMR. Therefore, CRP may be more sensitive marker of inflammation in these patients. Rapid improvement after corticosteroid treatment is not seen in FMS. On the contrary, patients may even feel worse!
PM may have a very indolent onset with nonspecific fatigue, lethargy, weakness, an acute-phase response may be absent, muscle enzymes may be normal or only mildly increased, electromyography tests and biopsies may be necessary.
Symptoms include: Nonspecific aches and pain, chronic fatigue, intolerance of exercise and cold environments, may be associated with loss of concentration and menstrual upsets and constipation.
But: Thyroxine levels are normal in FMS, myalgic symptoms respond to low dose thyroid replacement in hypothyroidism.
Common features: Insidious onset, reduced threshold for pain in the muscles, chronic fatigue, mild psychiatric disturbances (depression, attention)
But: Calcium, alkaline phosphatase, and parathyroid hormone levels are normal in FMS.
Ehlers–Danlos benign hypermobility joint syndrome
“Beighton score”: Dorsiflexion of 2nd finger to 90°, apposition of thumb to volar aspect of forearm, hyperextension of elbow by 10°, hyperextension of knee by 10°, hands flat on floor with knees extended.
Musculoskeletal disorders (diffuse idiopathic skeletal hyperostosis (DISH), Paget’s disease)
Common features: muscle pain and exercise intolerance
But: Physical examination may discriminate, good response to physiotherapy, in some cases of myopathy elevated creatine phosphokinase (CPK).
Statins in general well tolerated: used > 100 million people worldwide. But: In 0.9% for all statins occurs clinically relevant myopathy (muscle pain with CPK > 10x of the norm and also more than 29 cases of statin-associated autoimmune disorders (e.g., PM, dermatomyositis).
In daily practice: Stop statins if CPK > 5x norm and myalgia regresses after 2–3 months.
No association between FMS and cancer found.
But: Increased risk of female breast cancer among unconfirmed cases who did not meet the ACR criteria for FMS.
Other diseases to differentiate FMS with, include: FMS-like syndromes (4–19%) in hepatitis C; inflammatory/autoimmune diseases; mitochondrial myopathies; FMG and aromatase inhibitor; generalized musculoskeletal pain is a feature of many malignant diseases, such as multiple myeloma, metastatic breast, lung, and prostatic cancers.
Chochowska M, Szostak L, Marcinkowski JT, et al. Differential diagnosis between fibromyalgia syndrome and myofascial pain syndrome (Review article). J PreClin Clin Res 2015;9(1):82–86
Wolfe F, Smythe HA, Yunus MB, et al. The American College of Rheumatology 1990 criteria for the classification of fibromyalgia. Report of the Multicenter Criteria Committee. Arthritis Rheum 1990;33(2):160–172
Bennett R. Fibromyalgia, chronic fatigue syndrome, and myofascial pain. Curr Opin Rheumatol 1998a;10(2):95–103
14.3 Postherpetic Neuralgia
It is one of the most common types of neuropathic pain. This syndrome is characterized by prolonged pain after an episode of herpes zoster (HZ), classically known as shingles. After the acute rash of HZ has resolved, pain can often persist at the site of the healed rash. This pain, termed postherpetic neuralgia (PHN), is one of the most debilitating feature of HZ infection and can persist for months to years after initial HZ infection. The incidence of PHN varies between 9 and15% and increases with age, occurring in as many as 50% of the population older than 60 years. PHN is often defined as pain persisting for more than 3 months after the resolution of an HZ rash. (▶Fig. 14.1)
Fig. 14.1 (a) Postherpetic neuralgia 3 months after the rash. Skin lesions soon after rash healing surrounded by an area of anesthesia to punctate touch (solid line) and pinprick, with wider area of pain on moving touch of cotton or tissue (interrupted line). Moving the hair on this hirsute individual is exquisitely painful. Firm pressure is soothing. (b) Atrophy of the dorsal horn of the spinal cord in postherpetic neuralgia (arrows). (c) Scarring in the dorsal root ganglion with postherpetic neuralgia (arrows). (Reproduced from Practice. In: Burchiel K, ed. Surgical Management of Pain. 2nd edition. Thieme; 2014.)
PHN is caused by the varicella zoster virus (VZV), which causes two illnesses: the initial infection, known as chickenpox, and a reactivation illness known as herpes zoster or shingles. The virus gains access to and establishes latency within the dorsal root ganglia. Reactivation is associated with decline of cell-mediated immunity that may result from natural aging, AIDS, organ transplantation, or other causes of immunocompromised states.
The dermatomes from T3 to Le are most commonly involved in HZ (thoracic 55%, lumbar 10%, cervical 10%, and sacral 5%). However, in some cases, the virus may afflict the cranial nerves (trigeminal 20%) that leads to complications.
14.3.1 Diagnosis of PHN
Its diagnosis is based primarily on clinical features. Patients with PHN can exhibit a variety of pain and sensory patterns, including constant pain (burning or throbbing), intermittent pain (shooting or stabbing), and allodynia (pain caused by a nonpainful stimulus). Areas of hypoesthesia and hyperesthesia can also be present in the affected area, sometimes in combination.
Although a clinical diagnosis is often sufficient to those patients presenting with the classic HZ rash, laboratory testing can be useful for atypical presentations. Both immunofluorescence VZV antigen detection and VZV detection by viral polymerase chain reaction are excellent tests with high specificity and sensitivity (90–100%). Serologic testing of acute and convalescent VZV immunoglobulin G (IgG) titers can also be used in establishing the diagnosis of HZ.
Johnson RW, Dworkin RH. Treatment of herpes zoster and postherpetic neuralgia. BMJ 2003;326(7392): 748–750
Gnann JW Jr, Whitley RJ. Clinical practice. Herpes zoster. N Engl J Med 2002;347(5):340–346
14.4 Atypical Facial Pain
The pain usually starts in the upper jaw. Initially pain spreads to the other side, and back to below and behind the ear. Later, pain may spread onto the neck and the entire half head.
It occurs mainly with first-division herpes; although the whole zone hurts, the pain in the eyebrow and around the eye is especially severe. Pain is continual and burning, with severe pain added by touching the eyebrow or brushing the hair. The condition shows a tendency to spontaneous remission.
Swelling, redness, and tenderness of the temporal artery, and a headache in the distribution of the artery are the classic hallmarks of the disease. A diffuse headache can occur.
Cluster headache (migrainous neuralgia)
Nocturnal attacks of pain in and around the eye, which may become bloodshot, and nose “stuffed up,” with lacrimation and nasal watering. Bouts last 6–12 weeks and may recur at the same time each year.
TMJ dysfunction or Costen’s syndrome
Pain is mainly in the TMJ, spreading forward onto the face and up into the temporalis muscle. The joint is tender to touch and pain is provoked by chewing or just opening the mouth. The pain ceases almost entirely if the mouth is held shut and still.
A dull aching, throbbing, or burning pain that is more or less continuous and is triggered by mechanical stimulation of one of the teeth. It is relieved by sympathetic blockade.
Aching pain lasting from days to months and elicited by palpation of trigger points in the affected muscle.
Chronic aching pain involving the whole side of the face or even the head outside the distribution of the trigeminal nerve. This condition is much more common in women than in men and is often associated with significant depression.
Zakrzewska JM. Facial pain: neurological and non-neurological. J Neurol Neurosurg Psychiatry 2002; 72(Suppl 2):ii27–ii32
Nóbrega JCM, Siqueira SR, Siqueira JT, Teixeira MJ. Differential diagnosis in atypical facial pain: a clinical study. Arq Neuropsiquiatr 2007;65(2A):256–261
Agostoni E, Frigerio R, Santoro P. Atypical facial pain: clinical considerations and differential diagnosis. Neurol Sci 2005;26(Suppl 2):S65–S67
Quail G. Atypical facial pain—a diagnostic challenge. Aust Fam Physician 2005;34(8):641–645
14.5 Cephalic Pain
Classical migraine (hemicrania)
A pulsatile headache which starts in the temple on one side and spreads to involve the whole side of the head. Usually self-limiting lasting from 30 minutes to several hours.
Cluster headache (migrainous neuralgia)
Nocturnal attacks of pain in and around the eye, which may become bloodshot and nose “stuffed up,” with lacrimation and nasal watering. Bouts last 6–12 weeks and may recur at the same time each year.
Unilateral, shooting, boring headache, associated with lacrimation, facial flushing, and lid swelling that lasts 5–30 minutes day or night without remissions.
TMJ dysfunction or Costen’s syndrome
Pain is mainly in the TMJ, spreading forward onto the face and up into the temporalis muscle. The joint is tender to touch and pain is provoked by chewing or just opening the mouth. The pain ceases almost entirely if the mouth is held shut and still.
A dull aching, throbbing, or burning pain that is more or less continuous and is triggered by mechanical stimulation of one of the teeth. It is relieved by sympathetic blockade.
Pain is believed to be due to spasm in the scalp and suboccipital muscles, which are tender and knotted. It is described as tightness like a “band” or “scalp too tight” is a frequent clue.
Swelling, redness, and tenderness of the temporal artery, and a headache in the distribution of the artery are the classic hallmarks of the disease. A diffuse headache can occur.
A specific spot on the head is isolated and bizarre complaints such as “bone is going bad,” “worms crawling under the skin,” quickly followed by an invitation to feel the increasingly large lump. Usually nothing other than normal bulge in the skull is palpable. This condition should always be suspected if the patient offers to locate the headache with one finger. A relentless pressure feeling over the vertex is typical of simple depression headache.
Occurs on waking and is aggravated by bending or coughing, produces a “bursting” sensation in the head and does not respond well to analgesics.
Pain occurs as a persistent and occasionally progressive and localized symptom following head trauma with an onset usually many months after the accident. It may relate to an entrapped cutaneous nerve neuroma, extensive base of skull fractures associated with injuries of the middle third of the face, stripping of the dura from the floor of the middle fossa, following diastatic linear fractures, etc.
It is commonly a secondary manifestation of a benign process affecting the second cervical dorsal roots of the occipital nerves.
Carcinoma of the head and neck
Often a deep, boring, headache, debilitating in its progressive persistence, regional or diffused and induced by carcinoma of the face, sinuses, nasopharynx, cervical lymph nodes, scalp, or cranium.
Headaches related to brain tumors or mass lesions
A “cough” or “exertional” headache may be the sole sign of an intracranial mass lesion. Patients often wake up early in the morning with the headaches, which may be more frequent—daily versus episodically for migraine. Neurological examination may reveal focal abnormalities, as well as papilledema on fundoscopic examination.
Headaches related to ruptured aneurysms and arteriovenous anomalies
The onset of pain is usually sudden and it is severe or disabling in intensity and located bi-occipital, frontal, and orbitofrontal.
May present as an acute unilateral headache associated with facial or neck pain, Horner’s syndrome, bruit, pulsatile tinnitus, and focal fluctuation neurologic deficits from transient ischemic attacks. Dissections occur in trauma, migraine, cystic medial necrosis, Marfan’s syndrome, fibromuscular dysplasia, arteritis, atherosclerosis, or congenital anomalies of the arterial wall.
Approximately in 20–25% of patients who undergo a lumbar puncture, irrespective of whether or not there was a traumatic tap and regardless of the amount of cerebrospinal fluid (CSF) removed. Characteristically, the headache is much worse when the patient is upright, often associated with disabling nausea and vomiting and improves dramatically when the patient lies flat in bed.
These occur before and after orgasm. The pain is usually sudden in onset, pulsatile, fairly intense, and involves the whole head. The International Headache Society classification defines three types:
Dull type: Thought to be due to muscle contraction and by far the most common type occurring prior to orgasm and located in the posterior cervical and occipital regions.
Explosive type: The pain is excruciating and throbbing and is thought to be of vascular origin occurring at the occipital region at or just after orgasm. There is a family history of migraine in 25% of cases.
Positional type: Secondary to low-CSF pressure presumed due to dural tear and CSF leak, becoming worst in the upright position.
These headaches tend to be throbbing, often unilateral, and of brief duration (1–2 hours). Generally, benign in nature and thought to be due to migraine, secondary to increased intracranial venous pressure, muscle spasm, sudden release of vasoactive substances, or very rarely due to structural intracranial abnormalities such as Chiari abnormalities, tumors, or aneurysms.
Headache related to analgesics and other drugs
14.6 Face and Head Neuralgias
The 2nd and 3rd divisions are most commonly involved and the attacks have trigger points. The symptoms may be due to tumors, inflammation, vascular anomalies or aberrations, and MS. TN is the most frequent of all neuralgias.
Attacks of paroxysmal pains lasting for seconds or minutes, which are burning or stabbing in nature, and are localized to the region of the tonsils, posterior pharynx, back of the tongue, and middle ear. The causes may be idiopathic, vascular anatomic aberrations in the posterior fossa or regional tumors.
Attacks of paroxysmal pain along the distribution of the greater or lesser occipital nerve of unknown etiology.
Paroxysmal attacks of orbital pain caused or exacerbated by touching the medial canthus and associated with edema and rhinorrhea. It is of unknown etiology.
Neuralgia of sphenopalatine ganglion (Sluder’s neuralgia)
Short-lived attacks of pain in orbit, base of nose. and maxilla associated with lacrimation, rhinorrhea, and facial flushing. It affects elderly females and the cause is idiopathic.
Paroxysmal attacks of pain are localized in the ear, caused by regional tumors or vascular malformations.
Greater superficial petrosal nerve neuralgia (Vidian’s neuralgia)
Attacks of pain in the medial canthus associated with tenderness and pain in the base of nose, and maxilla brought out or triggered by sneezing. The etiology is idiopathic or inflammatory.
Neuralgia of intermedius nerve
Paroxysmal deep ear pain with trigger point in ear of unknown etiology. It may be related to varicella zoster virus infection.
Continuous trigeminal pain in hypoalgesic or analgesic territory of nerve. It occurs following percutaneous radiofrequency lesions or ophthalmic HZ.
Episodes of retro-orbital pain lasting for weeks or months associated with paralysis of CNs III, IV, the 1st division of V, the VI, and rarely the VII. There is intact pupillary function. It is caused by a granulomatous inflammation in the vicinity of the cavernous sinus.
Symptomatic neuralgia of the 1st division of CN V associated with Horner’s syndrome, and possibly ophthalmoplegia from middle cranial fossa pathology.
Continuous pain of the 1st and 2nd divisions of CN V with associated sensory loss, deafness, and CN VI palsy. It especially affects cases caused by inflammatory lesions in the region of the petrous apex after otitis media.
Zakrzewska JM. Differential diagnosis of facial pain and guidelines for management. Br J Anaesth 2013;111(1):95–104
Siccoli MM, Bassetti CL, Sándor PS. Facial pain: clinical differential diagnosis. Lancet Neurol 2006;5(3): 257–267
14.7 Trigeminal Neuralgia
It a neuropathic pain syndrome defined by the International Association for the Study of Pain (ISAP) as a “sudden and usually unilateral severe brief stabbing recurrent pain in the distribution of one or more branches of the fifth cranial nerve.” It is an excruciating, short-lasting (< 2 minutes), unilateral facial pain that may be spontaneous or triggered by gentle, innocuous stimuli and separated by pain-free intervals of varying duration (▶Fig. 14.2).
Fig. 14.2 MRI axial T1 image with contrast at the level of the midpons showing an aberrant loop of the superior cerebellar artery (red arrow) impinging on the root of the trigeminal nerve. The patient presented with clinical symptoms of trigeminal neuralgia. (Reproduced from 62.4 Trigeminal Neuralgia. In: Gasco J, Nader R, ed. The Essential Neurosurgery Companion. 1st edition. Thieme; 2012.)
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