Neuroscience Clerkship

 

 

CONVERSION REACTION

 
 

Sigmund FreudIn the late 1880s, Sigmund Freud, described conversion reaction as the manifestation of a repressed internal emotional conflict into an externalized physiological form.

According to the DSM IV, conversion disorders are characterized by the following:

1) unexplained symptoms affecting voluntary motor or sensory function in ways that suggest, yet are not fully explained by a neurological or other general medical condition, and

2) the presence of psychologic conflicts that play a significant role in initiating, exacerbating, and maintaining the disturbance. 
 

Above: Famous French neurologist, Charcot examining a woman suffering from "hysteria." The term hysteria is considered pejorative and no longer used. Instead the terms conversion reaction, functional disorder and somatoform disorder are generally used. Charcot saw patients who where blind, paralyzed, or who had some other physical symptom that under hypnosis, the abnormality would disappear. He inferred that the underlying problem was psychologic and not organic.
 

Conversion disorders and malingering are not the same! They lie on opposite ends of a spectrum of intentionality. Psychiatrically speaking, malingering is conscious and produces identifiable external gain, known as “secondary gain.” The secondary gain may be to obtain disability or litigation awards, or skip out on work. The malingering patient is actively and knowingly trying to fool the examiner.

A conversion disorder is strictly subconscious and is considered to be a manifestation of subconscious psychological distress. The gain is mainly primary gain, in that the main reason for the observed neurological dysfunction is an externalization of an inner subconscious psychological conflict. However, even in conversion disorder, some secondary gain may be present in that avoidance of an unpleasant situation, as well as attention by family, friends or care providers brought by the illness may be desired by the patient. The subconscious nature of conversion disorder, along with lack of clear motives, makes the identification of conversion disorder more challenging to neurologists than that of malingering patients.

A few general points are useful to keep in mind during the history of patients with potentially psychogenic neurological dysfunction. First, ill-defined or inconsistently described symptoms may raise a red flag, as should a pattern of chronic, changing complaints. Also, a pattern of family psychiatric disorders, substance abuse or illness may be correlated with non-organic symptoms, and certainly substance abuse or a history of mental illness in the patient may be suggestive. Finally, correlating the symptoms with social stressors or anxiety-inducing events may be illustrative.

Clearly, organic causes of symptoms need to be ruled out before a psychiatric diagnosis is made, however there are a number of history and physical exam techniques that may provide guidance. This can help reduce expensive and potentially risky diagnostic tests.

A first step to help confirm the diagnosis of conversion disorder may be to categorize the neurological dysfunction into motor, sensory or movement disorders. Movement disorders may include: psychogenic tremors, choreic movements, dystonia or pseudoseizures. By this distinction, one can systematically examine techniques that may guide selection of appropriate diagnostic testing and therapy.


Motor disturbances often take the form of hemiparetic and/or gait disturbances which may be represented as ataxia, trembling, or buckling of the knees. Several signs may indicate a psychogenic etiology. The most suggestive of both of psychogenic gait disturbances and of other manifestations of conversion disorders, is inconsistency of presentation among different examinations and with distraction of the patient. Other features include bizarre gait patterns, especially tandem walking with excessive arm waving and body swaying. The patient may demonstrate an inability to stand or walk, despite perfectly normal neurological exam while in bed, including sensory, propioceptive and cerebellar function. This gait is termed "astasia-abasia." It is important to consider midline cerebellar disease as an organic cause of gait disturbance, as this may not be readily detectible during the bedside exam.

As far as identifying psychogenic weakness or paralysis, the most objective aspect of the examination are the reflexes and muscle tone, over which the patient has little control. In testing strength to confrontation, the examiner will frequently find that the psychogenic patient exhibits initial strength followed by a "give-way quality". Furthermore, it may be possible to determine a psychogenic etiology by proceeding quickly from proximally to distally in the extremities. In this manner, the patient may not be able to think about which extremity is supposed to be weak, and it is possible to find that the limbs will give away bilaterally or not at all. This test is probably more useful in the malingering patient than the patient with true conversion disorder.

Charles F HooverAnother useful test, Hoover’s sign, described in 1908 by Charles Franklin Hoover, an American physician born in Cleveland, Ohio, may help differentiate between organic versus psychogenic weakness. The patient is asked to raise their paretic leg off of the bed against examiner’s resistance, while the examiner holds a hand under the opposite heel. A normal individual with or without hemiparesis will involuntarily contract the contralateral hip extensor, thus forcing down the contralateral heel in proportion to the upward force of the ipsilateral leg. However, a patient with a psychogenic weakness will not push down and may even lessen pressure on the “good” heel when asked to raise the “paretic” leg. This lack of reflexic, involuntary response, is due to poor effort, rather than true weakness, as in true weakness there should still be some degree of contralateral hip extension. This phenomenon is based on the principal of synergistic contraction described by Charles Sherrington in the 1890s in which contraction of one set of muscles (flexor or extensor) results in reflexic contraction of the opposite set of corresponding muscles (for those interested, in the history of Hoover's sign, click here).

 

 

The maneuver can be reversed (reverse Hoover’s sign) in the case of complete hemiplegia. The examiner places a hand under the heel of the hemiplegic leg and asks the patient to lift the contralateral normal leg. During straight leg elevation, the contralateral hip extensor will contract in a psychogenic patient, which can be perceived by the examiner. A truly hemiplegic limb should not contract by movement of the contralateral limb. It needs to be emphasized that this maneuver is only helpful if the leg is hemiplegic, not hemiparetic.

In addition, if a truly paralyzed arm is placed above a patient's face and dropped, it fall directly on the patient's face. In psychogenic weakness, the arm will pull away from the face as it is dropped, to avoid striking the face. Again, this is only valid if the arm is completely plegic.

Often, in psychogenic weakness, the patient will display profound weakness with formal confrontational testing; but will be able to perform informal or functional tasks without obvious difficulty (e.g., a patient may have profound hip weakness on exam; but can get up to the examining table without difficulty)

Another test that can be helpful in differentiating psychogenic from organic weakness due to corticospinal tract involvement is pronator drift. This is performed by having the patient hold both arms out in front of them, fully extended in a supinated position. In a patient with organic disease the affected limb will pronate gradually, while the normal limb will remain supinated. This is due to selective weakness of the forearm supinator as compared to the pronator in corticospinal tract damage. In a psychogenic patient asked to do this test, the “paretic” limb will usually fall straight down without pronating.

The following chart helps to summarize useful tools in differentiating psychogenic from organic weakness. Some of the tests are specifically designed for a corticospinal tract related weakness, whereas others are for all types of organic weakness. Note, that there is not one test that can help decide definitely if the weakness is organic or psychogenic, but rather it is the overall picture which is important.

 
HEMIPARESIS Psychogenic Organic
Tone symmetric usually asymmetric
Reflexes (DTRs and babinski sign) symmetric usually asymmetric
Hoover’s sign present absent
Give-away weakness present absent
Extensors vs flexors (corticospinal tract) usually no difference flexors may be stronger than extensors in corticospinal tract lesions
Proximal vs distal (corticospinal tract) usually no difference a distal to proximal gradient
Inconsistencies of strength (during formal exam versus informal observations) frequent rare
Sternocleidomastoid muscle weak turning toward paretic side weak turning away from paretic side or normal.
Pronator drift test (corticospinal tract) negative (lowering of weak limb, without pronation) positive (pronation of weak limb)
Gait drags paretic leg circumducts leg
Arm drop above head (in plegic arm) moves limb away from face limb hits face

Sensory disturbances are difficult to differentiate between psychogenic versus organic due to the inherently subjective nature of sensation. Nevertheless, there still exist helpful differentiating features. With non-organic sensory disturbance, the exam is inconsistent from examination to examination and also with distraction. An additional frequently referenced clue is that there is a non-physiological pattern of sensory abnormality. This means that the sensory disturbance is not in a cortical, dermatomal or peripheral nerve distribution. These may include: sharp demarcation of sensory change at the body midline, or a pattern of sensation disturbance that conforms with body parts. For instance, a patient may complain of anesthesia from the shoulder on down with a circumferential line of sensory loss that does not fit an organic sensory loss pattern. Or, the patient may have an apparent sensory level on the anterior chest that differs greatly from the sensory level on the back.

Methods to be used during the exam may include noting the timing of a patient’s “no” response when testing sensation with the eyes closed. It is suspect if the patient consistently says “no” to feeling sensation if spoken right at the instant of stimulation.

The zigzag test may be helpful. The patient’s eyes are closed and the border of sensory loss is marked. Then the examiner tests sensation for the normal sensory region, approaching that line in a zigzag fashion. In psychogenic sensory disturbances, the border will move toward the region of normal sensation and will continue to move into that region with repeated testing.

Psychogenic movement disturbances, may take the form of tremor, chorea, dystonia or other abnormal postures or movements. Pseudoseizures are among the most common of the psychogenic movement disorders. Unlike true seizures, pseudoseizures are often “less stereotyped.” This means that an inconsistent appearance from one episode to another occurs. Pseudoseizure may be triggered by an emotional event, whereas an epileptic seizure has variable or no specific trigger. Pseudoseizures are usually more gradual in evolution and longer in duration than epileptic seizures. Evolution of seizure refers to changes in the seizure manifestation from onset to the end of the seizure. Pseudoseizures may consist of side-to-side head movements, pelvic thrusting and random asynchronous movements, whereas real seizures are usually less limited in there array of movements. It is important to know that frontal lobe epilepsy may manifest with bizarre and varied movements that resemble a pseudoseizure. Patients with pseudoseizure are unlikely to injure themselves during the seizure, have tongue biting or urinary incontinence, whereas these are common after a generalized tonic-clonic seizure. The difficulty in diagnosing pseudoseizures stems from the knowledge that a high proportion of pseudoseizures occur among patients with true epilepsy. Patients that have history of psychiatric illness and especially sexual abuse have a higher incidence of developing pseudoseizures. . Additional physical findings that may suggest pseudoseizure rather than epileptic seizures is a retained ability to follow commands or talk during an event. However, a very focal partial seizure may not completely impair an ability to follow commands or talk.

Video EEG is the most useful diagnostic tool in differentiating true seizures from pseudoseizures by showing no electrographic seizures or epileptiform activity during a period of apparent seizure.

The table below summarizes the main differences between a pseudoseizure and true seizure.

  Pseudoseizure True seizure
Precipitant emotional trigger common variable or none
Stereotyped no usually
Evolution gradual quick
Length may last hours usually seconds to minutes (except status epilepticus)
Consciousness usually maintained usually impaired
Witnessed almost always variable
Psychiatric history frequent uncommon
Tongue biting, urination and injury rare common
EEG findings no electrographic seizure activity. usually electrographic seizure activity.

Ultimately, conversion disorder is a difficult diagnosis to make. Objective laboratory and imaging techniques are needed to exclude organic disease. A diagnosis of conversion reaction should always be made with caution. It is an error for physicians to dismiss unexplained symptoms as a conversion reaction. Often, they are wrong. Nearly all patients with conversion reaction have a past history of hypochondriasis or psychophysiologic reactions (often the hyperventilation syndrome). All symptoms need to be evaluated to exclude organic etiologies.

The other danger is that is easy to dismiss a patient's complaints after an inconsistent feature is seen, especially if some secondary gain is obvious. However, it is not uncommon that a patient has a true organic underlying condition, but also has a functional overlay, where they may exaggerate an otherwise subtle clinical finding.