Psychogenic Neurologic Deficits

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Chapter 3 Psychogenic Neurologic Deficits

Classic studies of hysteria, conversion disorders, and related conditions included patients who had only rudimentary physical examinations and minimal, if any, laboratory testing. Studies that re-evaluated the same patients after many years reported that as many as 15% of them eventually had specific neurologic conditions, such as movement disorders, multiple sclerosis (MS), or seizures that had probably been responsible for the original symptoms. In addition, some patients had systemic illnesses, such as anemia or congestive heart failure that might have contributed to their initial symptoms. Another interesting aspect of these studies is that many illnesses assumed to be entirely “psychogenic” in the first two-thirds of the twentieth century are now acknowledged to be “neurologic,” such as Tourette disorder, writer’s cramp, other focal dystonias, erectile dysfunction, migraines, and trigeminal neuralgia. To be fair, the medical community has still not reached a consensus on the etiology of several conditions, such as fibromyalgia, chronic fatigue syndrome, and some aspects of chronic pain. Also unexplained, in many patients, is weakness and disability for more than a decade after their physicians established a psychogenic basis for their symptoms.

Today’s physicians, who still fail to reach 100% accuracy, have at their disposal an arsenal of high-tech tests, including computed tomography (CT), magnetic resonance imaging (MRI), functional MRI (fMRI), electroencephalography (EEG), EEG-video monitoring, and genetic testing, as well as a full array of speciality consultants. In this setting, neurologists use their armamentarium mostly to exclude neurologic illnesses and thereby allow for a diagnosis of a psychogenic deficit. Preliminary reports, however, indicate that fMRI studies may help in establishing a diagnosis of conversion disorder.

The Neurologists’ Role

Even in the face of flagrant psychogenic signs, neurologists generally test for neurologic illness that could explain the patient’s symptoms, particularly those illnesses that would be serious or life-threatening. Although observing the course of the illness regularly proves most informative of its origin, neurologists tend to request extensive testing during the initial evaluation to obtain objective evidence of disease or its absence as soon as possible. They typically disregard the distinction between conscious and unconscious disorders. For example, their examinations do not allow them to differentiate patients with “blindness” due to an unconscious conflict from those deliberately pretending to be blind to gain insurance money. They consider gross exaggerations of a deficit, embellishment, as well as malingering as psychogenic. For various reasons, they bundle all psychiatrically related impairments into “psychogenic neurologic deficits.”

Within the framework of this potential oversimplification, neurologists reliably diagnose psychogenic nonepileptic seizures (PNES) (see Chapter 10), diplopia and other visual problems (see Chapter 12), and tremors and other movement disorders (see Chapter 18). In addition, they acknowledge the psychogenic aspects of headache (see Chapter 9), pain (see Chapter 14), sexual dysfunction (see Chapter 16), posttraumatic headaches and whiplash injuries (see Chapter 22), and many other neurologic disorders.

When consulting on patients who have been shown to have a psychogenic disturbance, neurologists usually offer reassurances, strong suggestions that the deficits will resolve by a certain date, and a referral for psychiatric consultation. Sometimes they provide patients acceptable, face-saving exits by prescribing placebos or nonspecific treatment, such as physical therapy. They avoid ordering invasive diagnostic procedures, surgery, and medications, especially habit-forming or otherwise potentially dangerous ones.

Patients often have mixtures of neurologic and psychogenic deficits, disproportionately severe posttraumatic disabilities, and minor neurologic illnesses that preoccupy them. As long as serious, progressive physical illness has been excluded, physicians can consider some symptoms to be chronic illnesses. For example, chronic low back pain can be treated as a “pain syndrome” with empiric combinations of antidepressant medications, analgesics, rehabilitation, and psychotherapy, without expecting either to cure the pain or determine its exact cause (see Chapter 14).

Psychiatrists, adhering to the preliminary version of the Diagnostic and Statistical Manual of Mental Disorders (DSM), 5th edition, will probably classify deficits that have originated in unconscious processes as a Conversion Disorder (Functional Neurological Symptom Disorder). In contrast, when individuals feign neurologic deficits to obtain “external reward,” psychiatrists would reasonably consider the activity Malingering or the expression a Factitious Disorder.

Psychogenic Signs

What general clues prompt a neurologist to suspect a psychogenic disturbance? When a deficit violates the laws of neuroanatomy, neurologists almost always deduce that it has a psychogenic origin. For example, if temperature sensation is preserved but pain perception is “lost,” the deficit is nonanatomic and therefore likely to be psychogenic. Likewise, tunnel vision, which clearly violates these laws, is a classic psychogenic disturbance (see Fig. 12-8). The caveat is that migraine sufferers sometimes experience tunnel vision as an aura (see Chapter 9).

Another clue to a psychogenic basis is a changing deficit. For example, if someone who appears to have hemiparesis either walks when unaware of being observed or walks despite seeming to have paraparesis while in bed, neurologists conclude that the paresis has a psychogenic basis. Another noted example occurs when someone with a PNES momentarily “awakens” and stops convulsive activity, but resumes it when assured of being observed. The psychogenic nature of a deficit can be confirmed if it is reversed during an interview under hypnosis or barbiturate infusion.

Motor Signs

One indication of psychogenic weakness is a nonanatomic distribution of deficits, such as loss of strength in the arm and leg accompanied by blindness in one eye, and deafness in one ear – all on the same side of the body. Another indication is the absence of functional impairment despite the appearance of profound weakness, such as ability to walk even though manual testing seems to show marked paraparesis.

Deficits that are intermittent also suggest a psychogenic origin. For example, a “give-way” effort, in which the patient offers a brief (several seconds) exertion before returning to an apparent paretic position, indicates an intermittent condition that is probably psychogenic. Similarly, the face–hand test, in which the patient momentarily exerts sufficient strength to deflect her falling hand from hitting her own face (Fig. 3-1), also indicates a psychogenic paresis.

FIGURE 3-1 In the face–hand test, a young woman with psychogenic right hemiparesis inadvertently demonstrates her preserved strength by deflecting her falling “paretic” arm from striking her face as the examiner drops it.

Another indication of unilateral psychogenic leg weakness is Hoover sign (Fig. 3-2). Normally, when someone attempts to raise a genuinely paretic leg, the other leg presses down. The examiner can feel the downward force at the patient’s normal heel and can use the straightened leg, as a lever, to raise the entire leg and lower body. In contrast, Hoover sign consists of the patient unconsciously pressing down with a “paretic” leg when attempting to raise the unaffected leg and failing to press down with the unaffected leg when attempting to raise the “paretic” leg.

FIGURE 3-2 A neurologist demonstrates Hoover sign in a 23-year-old man who has a psychogenic left hemiparesis. A, She asks him to raise his left leg as she holds her hand under his right heel. B, Revealing his lack of effort, the patient exerts so little downward force with his right leg that she easily raises it. C, When she asks him to raise his right leg while cupping his left heel, the patient reveals his intact strength as he unconsciously forces his left “paretic” leg downward. D, As if to carry the example to the extreme, the patient forces his left leg downward with enough force to allow her to use his left leg as a lever to raise his lower torso.

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