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The diagnosis of Tourette syndrome may be overlooked in patients with severe psychopathologic disorder but mild motor manifestations of Tourette syndrome.
To describe 4 patients with long-lasting general psychopathologic disorder and previously unrecognized mild motor and phonic tics exacerbated during adulthood by the onset of tremor; all of the patients had been referred for the evaluation of psychogenic tremor.
Four adult patients, with previous psychiatric diagnoses of depression (2 cases), generalized anxiety disorder (3 cases), malingering (1 case), and conversion disorder (3 cases).
Single case studies.
Clinical interviews disclosed that the 4 patients had positive family histories of Tourette syndrome, and all had mild motor and phonic tics that had started before the age of 18 years. On neurologic examination, 2 patients had bilateral postural tremor of the hands that varied in frequency, rhythmicity, and amplitude, and the other 2 had resting tremor mimicking parkinsonism. All 4 patients described involuntary somatic sensations of the affected limbs, which they attempted to alleviate by executing movements. No consistent positive placebo response was observed, but in all patients tremoric movements improved with haloperidol.
These cases illustrate an unusual movement disorder (tremor as a "tic equivalent") in adults with Tourette syndrome and emphasize that cases of the syndrome with mild tics often go unrecognized, precluding adequate treatment.
TOURETTE syndrome (TS) is a developmental neuropsychiatric disorder that appears in childhood or adolescence and is characterized by motor and phonic tics with a waxing and waning course during the individual's life.1 Tourette syndrome frequently co-occurs with a wide range of other psychiatric and behavioral disorders, and recent clinical studies have suggested that a percentage of adults with TS may have mild tic symptoms but severe psychiatric comorbidity (ie, anxiety and affective and personality disorders).2,3 Moreover, although maximal disability in TS occurs during childhood and adolescence, it is not rare that tics, behavioral problems, or both may be exacerbated in adulthood.4
While myoclonic and dystonic tics are not unusual among patients with TS,5,6 to our knowledge, tremoric movements (rhythmic and sustained movements) have not been described previously as possible tic equivalents in TS. Tourette syndrome and psychogenic movement disorders share many characteristics, such as the presence of associated psychopathologic disorders, bizarre movements that increase with anxiety and improve with distraction, and periods of spontaneous remission. Therefore, in patients with mild symptomatic TS and associated psychopathologic disorders, the onset of unusual movement disorders, such as tremoric movements incongruous with the common organic tremors during adulthood, could be misdiagnosed as psychogenic.
We describe 4 such patients with previously unrecognized mild TS, exacerbated during adulthood by the onset of tremor, who were all referred for the evaluation of psychogenic tremor.
The demographic and clinical characteristics of the 4 patients with TS are summarized in Table 1 and Table 2. All patients gave informed consent to be recorded on videotape. On evaluating videotape recordings, 2 raters (J.K. and A.A.) agreed completely on the diagnoses of tremorlike tics and other motor and phonic tics in the setting of TS.
A 71-year-old, right-handed woman with diagnoses of major depression and generalized anxiety disorder was referred by her psychiatrist for the evaluation of possible psychogenic tremor. She complained of a chronic tremor of her arms that had worsened in the 6 months before referral. Family history was notable for phonic tics affecting 1 brother. Her personal history showed that at age 11 years she had developed nail biting, throat clearing, and humming. At age 16 years she developed repetitive, stereotyped, bilateral stretching of the hands and fingers. The movements were preceded by uncomfortable, occasionally painful sensations in the upper limbs, and were associated with groans and guttural sounds. At age 20 years, the stereotyped movements had been replaced by bursts of bilateral, regular, clonic movements of the arms, lasting several seconds and occurring many times a day. As she did not consider these symptoms to be socially disabling, she did not seek medical help. At age 30 years, she was diagnosed as having recurrent major depression and generalized anxiety with agoraphobia and panic attacks, which were successfully treated with electroconvulsive therapy. Between 54 and 67 years of age, she intermittently received diazepam, alprazolam, amitriptyline hydrochloride, and nortriptyline hydrochloride but not neuroleptics. She reported that, since their appearance in childhood, phonic tics and arm movements had had a fluctuating course, with remission periods lasting several months. At age 68 years, when the recurrence of anxiety was accompanied by exacerbation of her tics, she was diagnosed as having psychogenic tremor by a local neurologist.
Results of neurologic and mental status examination were normal apart from occasional low-volume moans and abnormal shaking of the upper limbs (left more than right). Tremoric movements consisted of asymmetric bursts of stereotypic high-amplitude, 4- to 6-Hz rhythmic contractions of her shoulders, arms, and hands lasting more than 10 seconds each. They markedly diminished when she performed voluntary movements and increased with tasks that required concentration, such as mental counting. She was able to voluntarily suppress the abnormal movements for at least 3 minutes, during which she reported increased feelings of inner tension. Periods of voluntary control of the movements were followed by rebound exacerbation of motor tics and repetitive groans and sniffles. She also reported feelings of discomfort in her hands, which she attempted to alleviate by forcefully compressing her fingers. On the Tourette Syndrome Global Scale7 her total tic score was 10 (mild tic symptoms). Electroencephalogram, cranial computed tomographic scan, and blood screen results were normal. Tremor and feelings of inner tension improved with haloperidol, 2 mg/d, by at least 50%, according to the patient's opinion and tremor assessments made during consultation, including a videotape. In the 3 years of follow-up, tremor bursts waxed and waned in severity. During periods of improvement, upper limb tics had a more irregular, myoclonic appearance.
A 25-year-old, right-handed, single, unemployed woman was referred to us by her family physician, who advised her to have the degree of disability caused by tremor evaluated so that she could apply for government social assistance. She complained of bilateral, mainly right, bursts of postural tremor of her arms that had begun gradually 1 year earlier but worsened to the point of impairing daily activities, such as drinking, buttoning, and sewing. According to the patient, the tremor caused her to be dismissed from her former job. When previously referred by her family physician to another neurologist, she received the diagnosis of "psychogenic tremor, conversion disorder."
Her birth and early childhood had been unremarkable. She attended normal school until age 11 years, when she was withdrawn because she had severe attention problems and learning disability. Thereafter, she helped her mother in domestic tasks until she obtained her first job as a domestic worker at age 19 years. She reported no familial or personal history of tremor or tic disorder. She had never received stimulants, neuroleptics, or other dopamine receptor antagonists. During the first interview, when she was asked about her obvious phonic tics, she alleged that she had always made the same "normal" sounds. In a second evaluation when she was accompanied by her mother and her adolescent brother, it was noted that these relatives also exhibited a variety of motor and phonic tics (grunting, snorting, humming, and hissing). The patient's mother nevertheless denied having tics when they were pointed out and became upset at the neurologist's persistent questioning. Although she was aware of her daughter's tremor, she minimized the presence of phonic tics in her daughter and interpreted the motor tics (tics of the face, head, neck, and limbs) as the natural "nervousness" of her family.
On neurologic examination, the patient exhibited grunting, throat clearing and abnormal word accentuation, impaired fine motor coordination and alternating hand movements, and intermittent bursts of a coarse postural and kinetic tremor of the upper limbs, right more than left, lasting between 10 and 30 seconds. There was a marked increase in the tremor when her attention was drawn to her upper limbs. Fairly frequently, if distraction was accomplished by drawing her attention to another body part, the trembling limb became still for a while, but she became fidgety and exhibited camouflaged tics such as head shaking, along with twisting tonic movements of the neck and shoulders. When indicated, she could either voluntarily suppress or prolong tremor bursts. The patient explained that bursts of tremor were preceded by an unpleasant sensation—"like putting my arms in alcohol"—that was temporarily alleviated by the tremor. On the Tourette Syndrome Global Scale,7 her total tic score was 10 (mild tic symptoms).
Accelerometric and electromyographic recordings (Figure 1) showed prolonged bursts of a predominantly 6-Hz tremor with some fluctuation in tremor amplitude, many changes in tremor frequency to 4 and 5 Hz during the period of recording, lack of discharges of the antagonistic muscles, and a reduction of tremor with distractibility. Complete blood cell count and levels of acanthocytes, serum copper, ceruloplasmin, and uric acid as well as an electroencephalogram were all within normal limits.
Patient 2. Recordings of the accelerometric (top trace), agonistic (middle trace), and antagonistic (bottom trace) electromyographic activity of the outstretched right hand extended in front of the chest.
Neuropsychological testing showed a low-average IQ (verbal IQ, 75; performance IQ, 77). Personality was assessed by means of the Structured Clinical Interview for Personality Disorders (Version 1.0).1 She was found to meet full Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria8 for obsessive-compulsive, dependent, schizoid, and borderline personality disorders. A 1-month trial with propranolol hydrochloride (240 mg/d) was ineffective in reducing tremor. Haloperidol (1.5 mg/d) reduced both tremor and phonic tics by at least 30%, according to the patient's opinion and tremor assessments made during consultation, including a videotape. Although they did not completely subside, tremor bursts had a waxing and waning course in the 2 years of follow-up.
A 57-year-old, right-handed man who worked as a bricklayer was referred for evaluation of cephalic tremor and right-hand posturing and resting tremor of possible psychogenic origin. He had a long history of insomnia, obsessions of contamination, checking and arranging compulsions, and short temper. In addition, he had abused alcohol between 23 and 28 years of age. He reported that since the age of 25 years he had suffered discomfort in the shoulders and neck. At the age of 46 years, he was examined by a family physician and a neurologist because of a 2-year history of pain, paresthesia, and action and postural tremor of the upper limbs. A cervical root compression was suspected, but ancillary studies ruled out this possibility.
The patient was given an early retirement and had a presumed diagnosis of "generalized osteoarthrosis and tremor." At the age of 51 years, he again consulted a physician for worsening pain in the upper limbs and the cervical region. On examination, his family physician noticed intermittent cephalic and right-hand tremor and referred the patient to a neurologist, who diagnosed idiopathic Parkinson disease. He then received levodopa and a variable combination of anticholinergics, bromocriptine mesylate, pergolide mesylate, and selegiline hydrochloride during the next 7 years. Since tremor waxed and waned in severity during this period, the patient sought advice from at least 3 other local neurologists, who confirmed the diagnosis of Parkinson disease and varied the dosage and scheduling of antiparkinsonian drugs without observing beneficial effects. The referring neurologist advised the patient to withdraw all antiparkinsonian drugs for 1 month. As no aggravation of the tremor and no consistent rigidity or hypokinesia was observed after medication withdrawal, he questioned the diagnosis of Parkinson disease. Propranolol hydrochloride (120 mg/d) was then prescribed for 3 weeks, and no changes were observed in the patient's tremor.
The patient's prenatal, birth, and developmental history were normal. He had completed 10 years of education and functioned adequately with his classmates, but during his childhood he had developed facial and head tics, compulsive touching, phonic tics, spitting, and speech atypicalities. The patient reported that, although he was fully aware of having a repertoire of simple and complex motor and simple phonic tics that waxed and waned in severity since childhood, he was not embarrassed by these, because his father had had the same "habit" during his "entire life." His father had had facial and head tics, shoulder shrugs, and grunting.
The initial neurologic examination showed a lack of spontaneous movements combined with the intermittent appearance of prolonged bursts of tremor of the right arm that lasted up to 5 minutes. Examination with the arms outstretched at shoulder height showed a transient attenuation of tremor followed by the reappearance of a similar low-frequency prono-supination tremor of the right hand. While walking, the patient exhibited poor balance, a tendency to maintain a flexed posture of the right arm and hand, and a constant low-frequency, rotational tremor of the hand. Muscular tone and rapid alternating movements of the hands and feet were normal. Examination of the patient and review of videotape recordings showed that when the patient was relaxed and talking with the examiner of other nonpersonal issues, tremor disappeared and gesturing of the right arm was normal. However, stereotyped, mild-amplitude jerks of the head, neck, and shoulders and bizarre posturing of the legs became apparent. Drawing attention to his right arm led to the bursting reemergence of the highly stereotyped abnormal movements. At the moment of a tremor burst, the patient could voluntarily suppress the tremor in both the resting and the outstretched position of the right arm for several minutes, but low-volume grunts appeared, and simple motor tics of the neck and head grew in frequency and intensity. When the patient was confronted with the apparent paradox of a possible voluntary control of tremor with his enduring tremor documented during examination, he reported that the prolonged bursts of tremor were executed to attenuate painful feelings of constraint and elongation in his right shoulder and arm. He further explained that whenever he was under medical examination, he never attempted to suppress the tremor because he wanted to "help" and "satisfy" the understandable needs of the physicians to appreciate the characteristics of the tremor. During repeated neurologic examinations, the patient had mild simple motor and phonic tics as well as outbursts of the stereotypic right arm tremor. On the Tourette Syndrome Global Scale,7 his total tic score was 9 (mild tic symptoms).
Accelerometric and electromyographic recordings with the hands at rest showed no activity in the left arm. In the right arm, there were bursts of sustained (up to 3 minutes in duration), rhythmic, 6- to 7-Hz alternating activity mainly in agonistic muscles, with noticeable changes in frequency and amplitude with exercises of mental concentration (arithmetic calculation) (Figure 2). Results of laboratory investigations, including complete blood cell count, urinalysis, thyroid studies, serologic tests for syphilis (VDRL) by means of blood samples, and measurement of acanthocytes, serum copper, ceruloplasmin, and uric acid were all within normal limits. Results of an electroencephalogram and magnetic resonance image of the head were also normal. A brief mental status examination did not show cognitive deficits. On psychiatric examination, the patient obtained normal scores on the Spielberger State-Trait Anxiety Inventory (state, 12; trait, 14; no anxiety),9 the Beck Depression Inventory (6, no depression),10 and Obsessional Slowness Questionnaire (3, no slowness),11 but high scores on the Leyton Obsessional Inventory (symptoms, 25; traits, 12)12 and the Yale-Brown Obsessive-Compulsive Scale (obsessions, 10; compulsions, 10).13 He was treated with haloperidol (2 mg/d) and rapidly obtained a reduction in both painful sensations in the upper limbs and duration of tremor bursts of at least 50%, according to his opinion and tremor assessments made during consultation, including a videotape. There was, however, no modification in phonic tics and obsessive-compulsive symptoms, and during a 4-year follow-up, the patient experienced a waxing and waning of tremoric tics of the right upper limb.
Patient 3. Recordings of the accelerometric (top trace), agonistic (middle trace), and antagonistic (bottom trace) electromyographic activity of the right arm at rest. When the patient was unexpectedly requested to extend his left hand (arrow), this movement was accompanied by a sudden change in the frequency and intensity of the tremor of the right hand.
A 45-year-old, right-handed man who worked as a police officer was referred to the Movement Disorder Clinic at Sant Pau Hospital, Barcelona, Spain, by a neurologist from the National Health Service for evaluation of resting and postural tremor of the right leg. The tremor had appeared 1 year before consultation. During this period, the patient had experienced a feeling of "general nervousness" and uncontrollable movements of the right leg and had been diagnosed as having psychogenic tremor by a police force physician. A consulting psychiatrist further diagnosed him as having antisocial personality disorder and as being a malingerer. He was taking no regular medication, and there was no history of neuroleptic treatment. The patient described the movements as bursts of right leg tremor, present while sitting and standing still and lasting for several minutes. Movements were initially intermittent, lasting a few seconds, but progressing to a maximum severity during a 1-month period, with steadily increasing amplitude and duration of the tremor outbursts. The patient linked the tremor with an attempt to relieve an intense discomfort that he described as a stretching, tingling, or aching sensation of the right thigh aggravated by sitting and standing still, that escalated to painful tonic spasms when he attempted to restrain the tremor. These sensory experiences were more troublesome for the patient than was the tremor.
The patient had a history of childhood onset of mild simple motor tics, including hip posturing, shoulder shrugs, and head and neck jerks, as well as phonic tics such as sniffing, throat clearing, and uttering obscene words. Motor and phonic tics had a waxing and waning course, with 2 more symptomatic periods at ages 16 and 30 years, coinciding with stressful life events. Since adolescence, the patient intermittently experienced insomnia, depressive symptoms during the fall and winter period, aggressive obsessions to harm his family, and recurrent intrusive images of violence. He had married at the age of 25 years with the help of a marriage agency after meeting his wife through photographs. His marriage had always been stormy, and he continually accused his wife of turning their 2 children against him. He was paranoid and slept with a gun under the pillow. His wife informed us that she had formally denounced him to his superiors because of his physical abuse toward her and their children, promiscuous sexual behavior (unsafe sex with prostitutes), and use of confiscated drugs. Family history was notable for phonic tics and compulsive touching in his adolescent son.
On examination, a flexion-extension tremor was present in the right leg while sitting and when the leg was held in an outstretched posture. These movements were variably present up to 3 minutes in duration, with occasional attenuation when the examiner distracted the patient or drew his attention to other parts of the body. However, there was a marked increase in the tremor when his attention was drawn to the right leg. When asked to voluntarily suppress the tremor he was able to do so but complained, after approximately 30 seconds, of painful spasms in the right calf. The tremor and cramp sensation were relieved immediately on walking, but tremor again erupted soon after standing still and sitting down. Examination also disclosed frequent throat clearing, coughs, grunts, and sniffing, along with stereotyped hand-washing movements, repetitive shoulder shrugs, and adduction jerks of the thighs while sitting.
Accelerometric recordings obtained while sitting and while standing still showed prolonged bursts of a predominantly 8-Hz tremor with some fluctuation in tremor amplitude, occasional changes in tremor frequency to 5 and 9 Hz during the period of recording, and a reduction of tremor when the patient was distracted. On the Yale-Brown Obsessive-Compulsive Scale he obtained a total score of 21, and on the Leyton Obsessional Inventory his symptoms score was 18 and the traits score was 9. A psychiatric examination in the Department of Psychiatry, Sant Pau Hospital, confirmed the diagnosis of antisocial personality disorder on the basis of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria and advised against the patient possessing firearms in his work as a police officer. Neuropsychological examination disclosed average functioning in intelligence and memory tasks. Results of investigations including complete blood cell count; measurement of acanthocytes, serum copper, ceruloplasmin, and uric acid; and an electroencephalogram were all within normal limits. No changes in tremor were observed during a 3-week trial of flunarizine hydrochloride (10 mg/d), but subsequent treatment with haloperidol (1.5 mg/d) resulted in a marked reduction of the duration and number of tremor bursts of at least 50%, according to the patient's opinion and tremor assessments made during consultation, including a videotape; the reduction was sustained for 6 months. Thereafter, the patient was unavailable for follow-up.
A diagnosis of TS with bizarre tremor as a possible tic equivalent related to TS was made in all 4 of these patients, who had been referred to the Movement Disorders Unit at Sant Pau Hospital for evaluation of psychogenic tremor. All 4 patients shared the following clinical characteristics: (1) mildly symptomatic, previously unrecognized TS (all met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria by history and examination); (2) exacerbations of tic symptoms in adulthood; (3) intermittent, suppressible, highly stereotypic bursts of tremoric movements lasting minutes and preceded by premonitory sensory urges as the main persistent motor symptom; (4) comorbid general psychopathologic disorders (ie, obsessive-compulsive disorder, nonobsessive anxiety, depression, personality disorders) generally diagnosed before the onset of the unusual movement disorder; (5) motor symptoms incongruous with organic tremor; and (6) lack of response to usual antitremor drugs, thereby raising the suspicion of psychogenic movement disorder.
Clinical features of TS are heterogeneous and often complex. When present, the associated psychopathologic conditions of patients with TS may be quite disruptive, often representing the primary complaint.2 Although worst tic symptoms most frequently occur in childhood and adolescence,4 mild tic symptoms may go unrecognized in adult patients unless these patients specifically asked about them. Moreover, many adult subjects with TS diagnosed during childhood believed that their adulthood tics were clinically inconsequential. They often considered themselves to be recovered, even though they acknowledged the persistence of tics when questioned.4 Minimizing the presence of tics could be expected in subjects who are not aware that they have a tic disorder. Thus, in adult patients such as those described herein, it may not be unusual that psychiatric diagnoses other than TS may be prompted by the presence of comorbid psychopathologic conditions, particularly when mild tics or uncharacteristic symptoms (ie, tremoric movements) are observed during consultation.
Motor tics may be categorized phenomenologically as either clonic (brief, jerking) or tonic (sustained, dystonic) movements that occur irregularly as single discrete tics and occasionally in bursts of several tics.6,14 In our patients, the more or less rhythmic and lasting movements with the appearance of tremor were not interpreted as tics even though all patients were seen by neurologists and despite the fact that their tremoric movements fit most of the criteria of a tic: intermittency (lasting a few seconds), suppressibility, highly stereotyped, preceded by an urge, and occurring in the context of other tics. However, on reviewing the literature, we found that tremoric tics are not the sole motor manifestation of TS that may be misdiagnosed. When the clinical expression of TS is dominated by tonic tics (ie, more sustained movements), the disorder is sometimes wrongly diagnosed as dystonia,5,15 whereas other patients with multiple tics occurring simultaneously may resemble those afflicted with multifocal myoclonus or chorea.6 Furthermore, tics occurring in the form of prolonged bursts of regular, rhythmic, and repetitive clonic movements are not exceptional15 and might be conceptualized as complex tics.
The pathophysiological mechanism underlying the lasting repetitive presentation of tics with the appearance of tremor in our patients is unknown. We hypothesize that this phenomenon may be related to the occurrence of a poor habituation (ie, a lack of decreased magnitude of response with repetitive presentation of the triggering stimulus) or a sensitization to the presence of sensory tics. All 4 patients experienced uncomfortable sensations that resulted in feelings of discomfort, for which they attempted to obtain relief by producing movements involving the affected body region, a succession of symptoms referred to as "sensory tics."16 In this setting, the executed movements are usually described as tonic tightening or stretching of muscles, often lasting one second or more.16 Relief of the uncomfortable sensations is temporary, however, and the movements are repeated.17 We suggest that the sensory experiences preceding the tic symptom in some patients may result in the establishment of a rapidly reemergent circuit, accounting for the lasting production of repetitive tics with a rhythmic appearance. This functional circuit, in which the increased sensory input seems to repeatedly overcome the stimulus barrier and rapidly trigger more tics, thereby creating a reverberant feedback, could be related to the reiterative recruitment of sensorimotor, corticothalamocortical brain circuits.18 Either a poor habituation or a sensitization phenomenon (ie, a decreased latency of response with repeated stimuli) to the sensory inputs may underlie the short intervals at which the stereotyped movements ("tremoric" tics) are produced in these patients. From a psychological perspective, one can also speculate whether the rapid, pseudorhythmic nature of our patients' tics may underscore a strategy for lessening the need to suppress tics. Simply letting the tics occur at their ease and thus giving them the appearance of tremor, a more "socially acceptable" involuntary movement, would prevent the rise of inner tension.
Since abnormal movements are relatively common among patients with psychiatric disorders, even those who never received neuroleptics,19 it could be argued that tremor in patient 2, with a personality disorder including schizoid traits; and in patient 4, who was clearly paranoid, were related to these dramatic psychiatric disorders per se rather than being part of the spectrum of TS. It should be noted that hyperkinetic movements including complex stereotypies, mannerism movements, iteration (ie, monotonous, rhythmic repetition of motor acts), and parakinesia (a continuous, irregular jerking and twitching resembling chorea, athetosis, or tics) are at most only superficially reminiscent of tremor seen in our cases.20 Moreover, stereotypies and mannerisms have been mainly described among patients with schizophrenia, catatonia with "positive" phenomena, mania, agitated depression, and severe anxiety,21 but not among patients with personality disorders. On the other hand, our report suggests that adult patients with severe psychopathologic disorders but mild motor manifestations of TS can easily be diagnosed as having psychogenic (ie, noninvoluntary) movement disorder. Besides the associated psychopathologic conditions, tics of TS share many features considered characteristic of psychogenic movement disorders, such as increased occurrence with anxiety, improvement with distraction, periods of spontaneous remission, and the "voluntary" nature of the movement.22,23 Although such a distinction may not be appropriate, tics are on the border between voluntary and involuntary and, not rarely, patients with sensory tics say that their movements are entirely voluntary, with the intention of dealing with the sensory symptom.24 The presence in our patients of outstanding clinical features recognized as incongruous with an "organic" tremor (ie, fluctuations in amplitude and frequency, tremors that suddenly erupt and then cease in the course of a few minutes, unresponsiveness to antitremor drugs) and the presence of associated psychopathologic conditions substantially contributed to the working diagnosis of psychogenic tremor.25
Accepted for publication August 14, 1997.
Supported in part by grant FIS 97/2027 from Fondo de Investigaciones Sanitarias, Madrid, Spain (Dr Berthier).
Presented in part at the 48th annual meeting of the American Academy of Neurology, San Francisco, Calif, March 26, 1996.
Reprints: Jaime Kulisevsky, MD, Movement Disorders Unit, Department of Neurology, Sant Pau Hospital, Sant Antoni M Claret, 167, 08025 Barcelona, Spain (e-mail: firstname.lastname@example.org).
Kulisevsky J, Berthier ML, Ávila A, Gironell A, Escartín AE. Unrecognized Tourette Syndrome in Adult Patients Referred for Psychogenic Tremor. Arch Neurol. 1998;55(3):409-414. doi:10.1001/archneur.55.3.409