Am Fam Physician. 1998;57(10):2485-2494
Physicians may encounter patients with a collection of psychologic disorders that present with neurologic symptoms or signs, yet have no identifiable structural or functional etiology within the nervous system. These disorders comprise the so-called pseudoneurologic syndromes, which can mimic almost any organic disease. A careful history and physical examination often can identify the psychologic origin of the symptoms. Presenting syndromes can include pseudoparalysis, pseudosensory syndromes, pseudoseizures, pseudocoma, psychogenic movement disorders and pseudoneuro-ophthalmologic syndromes. These presentations may be distinguished from organic disease by observing signs and symptoms or eliciting test responses that are nonphysiologic and incompatible with organic disease. Once a pseudoneurologic syndrome is identified, patients require compassionate and understanding care to resolve underlying emotional problems.
When the mind-body relationship becomes unbalanced to the point of a diseased state, the psyche can manifest several well-described disorders such as somatization disorder, conversion disorder, psychogenic pain disorder and factitious disorder. Perhaps the most common constellation of presenting symptoms and signs for these disorders are neurologic,1 and they constitute the pseudoneurologic syndromes discussed in this review.
The nomenclature used to describe these conditions is confusing and overlapping. Terms such as “hysteria,” “conversion,” “functional,” “nonorganic,” “simulated” and “psychogenic” have been used interchangeably and are not clearly defined. For the purpose of discussion in this review, the terms “psychogenic” or “pseudoneurologic” will be used to refer to neurologic symptoms for which a psychologic etiology is suspected.
The significance of these conditions to the primary care physician cannot be overemphasized.2
From 25 to 72 percent of patient visits to primary care physicians are primarily the result of psychosocial distress presenting as somatic complaints.3,4 Conservative estimates indicate that at least 10 percent of all medical services are provided for patients who have no evidence of organic disease.5 Early diagnosis of pseudoneurologic syndrome spares the patient unnecessary, expensive and invasive procedures.
The economic impact of pseudoneurologic syndrome is tremendous. Patients with somatization have overall health care expenditures nine times that of unaffected persons, and over 82 percent of patients with somatization stop working because of their health problems.3 This translates into a cost of $20 billion in health care expenditures annually, not counting time lost from work and disability payments.6 Even a modest improvement in recognition and treatment of somatizing disorders could reduce health care costs significantly.
The major pseudoneurologic syndromes are summarized in Table 1. The pseudoneurologic syndromes can mimic almost any organically based disease. A thorough history and neurologic examination are the most important aids to the clinician in distinguishing organically from psychologically based disease. Clues to the diagnosis of pseudoneurologic syndrome are outlined in Table 2. Although these clues do not rule out organically based disease, they should raise the clinician's suspicion for pseudoneurologic syndrome. In particular, objective findings such as normal reflexes, muscle tone and pupils are rarely altered by psychogenic causes, and pseudoneurologic syndrome often does not follow neuro-anatomic (e.g., dermatomal) patterns.
|Pseudosensory syndromes (e.g., deafness, anesthesia)|
|Psychogenic movement disorders|
|Precipitated by stress|
|Occurs or worsens in the presence of others|
|Signs of other psychiatric illness (panic attacks, depression, schizophrenia)|
|History of multiple surgeries (e.g., appendix, gallbladder, adhesion, nerve entrapment)|
|No serious injuries sustained despite falls or “seizures”|
|Denies psychologic etiology of symptoms|
|Normal reflexes, muscle tone, pupillary reaction, etc.|
|Symptoms persist despite specific medical treatment|
|Alexithymia: inability to describe feelings in words|
|Vague, bizarre, inconsistent description of symptoms by patient|
|Striking inconsistencies on repeated examination|
|Nonanatomic distribution of abnormalities|
The psychiatric profile of patients with pseudoneurologic syndrome can be categorized using the classification of the somatoform disorders (somatization disorder, conversion disorder, psychogenic pain disorder, hypochondriasis and undifferentiated somatoform disorders) and factitious disorder given in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).7 Somatization disorder and conversion disorder are subconscious expressions of psychologic stress in the form of somatic complaints.8 Like somatization disorder, conversion disorder is nonvolitional but presents with the sudden onset of single, usually nonpainful symptoms that are precipitated by stress. Symptoms occur mostly in adolescent or young adult women from socioeconomically deprived backgrounds.8,9 Factitious disorder is a conscious fabrication of disease for personal gain.10 Psychogenic pain syndromes (e.g., somatoform pain disorder)11 will only be discussed in the context of other pseudoneurologic syndromes.
Psychogenic disorders coexist with organic neurologic disease in up to 60 percent of patients and offer no immunity against any disease process.13 Careful laboratory and radiologic investigation may be required to exclude an organic etiology. The following discussion illustrates the salient features of pseudoneurologic syndrome that may allow clinicians to differentiate organic from psychogenic etiologies (Table 4).
|Pseudosensory syndromes||Tuning fork test|
|Bowlus and Currier test|
|Pseudoseizures||No lateral tongue biting|
|No postictal confusion|
|Geotropic eye movements|
|Normal “ictal” EEG|
|Normal serum prolactin level|
|Pseudocoma||Normal caloric-provoked nystagmus|
|Pseudoblindness||Normal pupils and OKN|
|Hysterical aphonia||Pressured whispering|
Patients with pseudoparalysis usually report involvement of a single limb or one half of the body. On physical examination, they have normal reflexes, muscle tone and sphincter functions, and negative Babinski signs. The weakness does not follow anatomic patterns and is not consistent on repeated examinations. With pseudohemiparesis, the face, tongue, platysma and sternocleidomastoid are usually not affected. When the sternocleidomastoid is affected, patients have apparent weakness on the wrong side because the sternocleidomastoid normally aids in turning the head in the opposite direction.
The patient with pseudoparalysis may have “give-way” weakness: abrupt or stepwise loss of strength in the tested muscle groups. In contrast, the loss of resistance is smooth in patients with organic weakness. Patients with pseudoparalysis have equal weakness of both agonist and antagonist muscles, whereas true paresis affects the extensor muscles more than the flexors.
A few bedside tests are often helpful in patients with suspected pseudoneurologic syndrome. The first is a drop test: the clinician drops the “paralyzed” arm over the patient's face. In pseudoneurologic syndrome, the “paralyzed” arm will not strike the patient's face when dropped (i.e., a near miss). Second, the clinician can test weakness with painful stimulation. Unexpected painful stimuli to the affected extremity may cause a purposeful withdrawal response.
A third test that is useful is the Hoover test. The physician places one hand under the heel of the patient's “weak” leg while pressing down with the other hand on the good leg. Now the patient is asked to lift the good leg against resistance. If the physician feels counterpressure under the “weak” leg, it normally means that the “affected” leg is not paralyzed. The physician can then switch hand positions and ask the patient to lift the “weak” leg. If there is no counterpressure under the good heel, the patient is not being compliant.
A final useful test is the adductor sign. Normally, adduction of one thigh is accompanied by reflex adduction of the opposite thigh. To test the adductor's sign, palpate both of the adductors and ask the patient to adduct with the good side. The “weak” side will be felt to contract normally.14
Pseudosensory syndromes are common pseudoneurologic presentations. Patients with pseudosensory syndromes complain mainly of numbness (anesthesia). Symptoms often follow the patients' own concept of their anatomy. All sensory modalities (touch, pain, vibration, proprioception) disappear at a discrete border (joint or skin crease or mid-line), unlike true sensory loss where overlapping borders and different borders exist for the various sensory modalities.14
One common pseudosensory presentation is hemisensory loss with a nonphysiologic midline sensory split including genitals, hearing, vision, smell and taste, but sparing the back. True hemianesthesia does not split the genitalia because of overlapping innervation.
Several bedside tests may be useful. First, the clinician may observe that painful stimuli applied to a “numb” extremity often increase the pulse rate by 20 to 30 beats per minute: a normal finding. In addition, unexpected painful stimuli may result in withdrawal of the “numb” extremity. Second, the clinician may try the tuning fork test by applying a tuning fork to a bony structure covering a hollow cavity. Vibratory loss on one half of the skull, sternum or pelvis is thought to be physiologically impossible because of bone conduction. The presence of vibratory loss over these surfaces suggests a pseudosensory syndrome.
A third test is the Bowlus and Currier test.15 In this test, the patient's arms are extended and crossed with thumbs down and palms facing together. The fingers are then interlocked and the hands rotated downward, inward and up in front of the chest. The fingertips end up on the same side of the body as their respective arms. The thumbs are not interlocked so that they lie on the side opposite the fingers. With true sensory impairment, a patient can quickly identify fingers with normal and abnormal sensation when rapid sharp tactile stimuli are applied. Patients with pseudosensory deficits confuse the lateralization, causing them to make many mistakes identifying digits when sharp stimuli are applied to them.15
Another useful test is the “yes-no” test. When testing the sensation of touch, have patients close their eyes and give “yes” responses when they perceive they are being touched and “no” responses when they perceive that they do not feel a touch. A repeated “no” response when a supposedly numb limb is touched favors a pseudosensory syndrome.
Finally, the clinician may test proprioception of the big toe. Patients with pseudosensory syndromes may erroneously identify the position of the big toe 100 percent of the time. In contrast, a rate of at least 50 percent accuracy would be anticipated with an organic lesion based purely on chance.
In cases where it is difficult to discern the organicity of sensory loss, somatosensory evoked responses also may be useful.
Pseudoseizures are probably the most difficult pseudoneurologic syndrome to distinguish from the organic equivalent, epileptic seizures. Epileptic seizures are frequently misdiagnosed as pseudoseizures, and vice versa. The use of video electroencephalographic (EEG) telemetry is often necessary to distinguish the two with certainty.
Pseudoseizures are prevalent and can coexist with epileptic seizures. From 5 to 35 percent of patients with pseudoseizures also have epilepsy and may be taking therapeutic doses of anticonvulsant medication.16 Intensive monitoring of patients with intractable seizures reveals that 35 percent of patients with presumed drug-resistant epilepsy have pseudoseizures.
No single clinical finding reliably differentiates epileptic seizures from pseudoseizures. Pseudoseizures are involuntary and refractory to anticonvulsant medication, and can mimic generalized convulsive seizures, absence seizures or complex partial seizures.17 Non-convulsive pseudoseizures are more common than convulsive ones. Patients with pseudo-seizures often have a history of abuse or trauma, a familiarity with epilepsy (e.g., in a family member or as an allied health professional), are female and have onset of seizures in the late teens.
The history of the seizure is often helpful. Pseudoseizures may be suspected if the patient is able to act out or recall precisely what occurred during the seizure.18 Clinical features that suggest pseudoseizures include seizures that follow stress or occur in the presence of an audience. Clinical features of pseudoseizures vary from one seizure to the next, while epileptic seizures are stereotypical. Pseudoseizures have a gradual onset, whereas epileptic seizures tend to start abruptly. Symptoms at the onset of pseudoseizures that can be confused with seizure auras include palpitations, choking, numbness, pain and visual hallucinations.
The traditional wisdom that self-injury during a seizure excludes a psychogenic etiology is not always true. While such injuries remain more common in epilepsy, they also occur in pseudoseizures as a reflection of self-destructive behavior. However, patients with pseudoseizures usually lower themselves gradually to the ground to avoid injuries. Skin burns (that occur while cooking, for example) during seizures may have greater diagnostic significance as they occur in one third of epileptic seizures but not in pseudoseizures. Bladder incontinence and tongue biting are not exclusive to epileptic seizures, since they occur separately or together in about one half of EEG-proven pseudoseizures. The number does not differ significantly from that in patients with epileptic seizures.19 Lateral tongue biting and scarring are more suggestive of epileptic seizures, whereas biting on the tip of the tongue suggests pseudoseizures.20 The mouth is usually wide open during the tonic phase of a generalized epileptic convulsion. The presence of clenched teeth during the “tonic spell” should raise suspicion for pseudoseizure.
Pseudogeneralized tonic-clonic seizures often appear as bizarre contractions that have little similarity to epileptic generalized tonic-clonic seizures. Patients with pseudogeneralized tonic-clonic seizures have asynchronous jerks of the arms and legs that can last minutes to hours, side-to-side head movement, pelvic thrusting, wild kicking, geotropic eye movements (the eyes deviate toward the bed as if pulled by gravity even if the patient is turned to the other side), and no ictal amnesia or postictal confusion.16 Unlike patients with epileptic generalized tonic-clonic seizures, these patients frequently have responses to painful stimuli, resistance to eye opening, intact corneal reflexes, reactive pupils, normal caloric responses and absent Babinski signs. Abdominal muscles do not contract in these patients as they do in patients with epileptic generalized tonic-clonic seizures.16,21
Pseudogeneralized tonic-clonic seizures may be terminated by painful stimuli. Events that are related to either inducing or stopping seizures are suggestive of pseudoseizures. Psychogenic status epilepticus that is induced or relieved by saline injection has been reported recently.22 Normal EEG activity during a seizure brought about by skillful suggestion is diagnostic.
If the clinician is uncertain about whether an event is an epileptic seizure or a pseudoseizure, measurement of the serum prolactin level may be helpful.23 Serum prolactin levels increase significantly (at least threefold) within 20 minutes of the beginning of the epileptic seizure in 96 percent of generalized tonic-clonic seizures and 60 percent of complex partial seizures without generalization. Normal or slightly increased levels of prolactin are associated with pseudoseizures but also with simple partial seizures and frontal lobe seizures.24
Psychogenic Movement Disorders
Psychogenic movement disorders can mimic the entire spectrum of true movement disorders, including tremor, parkinsonism, myoclonus, dystonia, tics and dyskinesia.25
The clinician should suspect psychogenic movement disorder when the onset, course or manifestations of the disorder are unusual. For example, psychogenic movement disorder should be suspected when the patient fails to experience the abnormal movements or posture while distracted. Commonly, clinicians use placebo drugs in an attempt to exacerbate or improve symptoms in suggestible patients. Although the ethics of this practice are debated, it can be an effective diagnostic tool.26 Other tests that may augment a clinician's ability to diagnose psychogenic movement disorder include videotaping the suspicious movements and electromyography.
Pseudotremor is the most common psychogenic movement disorder and is often mistaken for physiologic tremors such as essential tremor or medication-induced tremor but not the resting tremor associated with parkinsonism. Pseudotremor usually involves one limb and is intentional, and may disappear when the patient is distracted and reappear in another limb if the involved limb is restrained.26 The majority of patients with pseudotremor have an abrupt onset of the disorder. The pseudotremor often has a complex mixture of resting, postural and action qualities,27 and may have a fluctuating course, spontaneous remission or changing characteristics.
Psychogenic parkinsonism is characterized by abrupt onset with no evolution over time, spontaneous improvements, remission with psychotherapy and inconsistent tremor or bradykinesia.28 In one series,29 more than 50 percent of patients with psychogenic parkinsonism had atypical features of resting tremor, such as variation in frequency and rhythmicity, presence during action or ability of the tremor to become converted to other motions. These patients also commonly had hysterical gaits.
Psychogenic myoclonus has been described and has several typical features: decrease of the myoclonus with distraction, periods of spontaneous remission, episodic acute improvement in symptoms, improvement with administration of a placebo, and presence of associated psychopathology.30
Psychogenic dystonia is uncommon but well described. Clinical features include abrupt onset, rapid progression to fixed dystonic postures, predominant involvement of the legs, frequent complaints of pain, and paroxysmal worsening in over 50 percent of cases. All of these features are inconsistent with the established forms of organic dystonias.31 Differentiation may require an empiric trial of medication with phenytoin (Dilantin) or anticholinergic agents. Other paroxysmal psychogenic movement disorders such as dyskinesias and tics have also been described.32
Pseudocoma is perhaps as difficult to diagnose as pseudoseizure and should be a diagnosis of exclusion because, if true coma is missed, the complications could be life-threatening. Patients must therefore undergo standard treatment for coma until the diagnosis is clearly established.
Like pseudoseizures, no one piece of historic data absolutely includes or excludes the possibility of pseudocoma. However, pseudocoma should be suspected when the history reveals that alteration of consciousness was precipitated by stress. Pseudocoma usually begins with an observer present. Patients with pseudocoma “slump” to the floor and avoid hitting their heads.21
Patients with pseudocoma usually resist examination and make semipurposeful avoiding movements. They have normal pupils, corneal reflexes, plantar reflexes and sphincters. They may keep their eyes closed tightly and resist attempts to open them (in organic coma, the eye closure is very slow and very difficult to simulate). Patients with pseudocoma have Bell's phenomenon (the eyes roll up when the lids are raised), whereas in patients with true coma, the eyes remain in a neutral position. Patients with pseudocoma display geotropic eye movements. Pseudocoma patients may respond with purposeful movement to painful stimulation and avoid unpleasant stimuli such as tickling of the vermilion border of the lip. Like patients with pseudoparalysis, the hands of patients with pseudocoma often will just “miss” when dropped toward their faces.21
Caloric testing with cold water is the most useful adjunct to the bedside examination. Nystagmus with caloric testing proves that coma is either feigned or hysterical, because nystagmus requires an intact cerebral cortex and brainstem. Additionally, cold water caloric stimulation is noxious and can induce nausea, vomiting or recovery in a noncomatose patient.
Most patients with pseudocoma “wake up” in the emergency department after repeated examinations and become very uncooperative. The “comatose” period should be used to obtain blood and urine samples and to do a thorough physical examination.
A hysterical gait can present with monoplegia or monoparesis, hemiplegia or hemiparesis, or paraplegia or paraparesis. With hysterical gait, there tends to be no leg circumduction, hyperreflexia or Babinski sign. Characteristic features of a patient with hysterical gait include sudden buckling of the knees (usually without falls), swaying with the eyes closed with a buildup of sway amplitude and improvement with distraction.33 Patients with a hysterical gait tend to drag the foot when walking rather than lift it.
Hysterical gaits can be dramatic, with patients lurching wildly in all directions, thus demonstrating a remarkable ability to do rapid postural adjustment. In contrast, patients with true paresis or paraplegia of the lower extremity tend to fall frequently. An unusual and illusive presentation of hysterical gait is known as astasia-abasia. In this condition, the patient is unable to turn or walk but retains normal use of the legs while lying in bed. However, atrophy of the vermis and frontal gait disorders (gait apraxia) can have similar presentations.34
Pseudoneuro-ophthalmologic syndromes can mimic any pathology that affects the visual or oculomotor systems. The most common presentation of pseudoneuro-ophthalmologic syndrome is blindness.35 Patients complain of sudden and complete loss of vision. Normal pupillary reaction and optic fundi exclude all organic causes, except cortical blindness, which is excluded by a normal optokinetic nystagmus response to horizontal or vertical movements of a striped drum. Alternatively, the clinician may place a mirror in front of a patient with pseudoblindness and gradually tilt the mirror from side to side. Humans reflexively tend to follow the reflection of their eyes or to look away from the mirror each time it is placed in front of them.
Another pseudoneuro-ophthalmologic presentation is tunnel vision,35 where fields remain the same in inches at varying distances. In contrast, funnel vision (a physiologic condition) produces fields that expand in inches (but remain the same in degrees) proportionate to the distance viewed.
Diplopia is another pseudoneuro-ophthalmologic presentation.35 True monocular diplopia (double vision with one eye covered) is very uncommon and indicative of pathology within the globe, such as retinal detachment or lens problems.36 Nonorganic diplopia should be suspected in patients who present with monocular diplopia, especially if the ocular funduscopic examination is normal.35
The final pseudoneuro-ophthalmologic presentation is ptosis. Convincing voluntary ptosis can be achieved with practice. Ptosis is frequently a presenting symptom of conditions such as myasthenia gravis and chronic progressive external ophthalmoplegia. The diagnostic clue is the presence of ipsilateral eyebrow depression with pseudoptosis rather than the brow elevation that occurs with true ptosis.35
Aphonia is defined as the absence of vocalization or phonation and differs from mutism, which is the absence of speech. Hysterical aphonia is characterized by a normal whisper and cough. Examination with a laryngoscope reveals normal vocal cord movement with respiration.
Pseudoneurologic syndromes occasionally occur, and primary care physicians should be familiar with them. A careful history and physical examination give the best clues to an accurate diagnosis, which can save time and money by avoiding exhaustive and expensive investigations and prevent suffering caused by invasive procedures.
Patients with pseudoneurologic syndromes deserve the same compassionate treatment as any other patient. They are behaving in what seems to be the only cultural and situational manner appropriate for them. They should never be ridiculed. Rather, they should be given the support, time and encouragement needed to return to normal function. Consultation with a psychiatrist or psychologist is often helpful, since these patients typically have emotional issues to deal with even after the pseudoneurologic syndrome resolves.