The history and examination of patients suspected having brain disease are not standard. They vary from patient to depending on the presenting complaint. If every function that could be assessed were examined in patient, each evaluation would require at least a full day. Testing all sensory modalities, including olfaction, hearing, vision, taste, and somatosensory functions as well the interpretation of and memory sensory stimuli, speech, numerical calculation, cerebellar function, and each cranial nerve might be excessive in a young woman with many years of typical migraine headaches, for example.
The history, appearance, and behavior of the patient indicate which functions are appropriate to test. Patients with disorders of behavior and thought must have a thorough examination of the functions that are mediated in cerebral hemispheres.
Neurology and psychiatry are medical specialties that deal with a single organ, the brain. This separation within the medical profession should not prevent us from evaluating our patients appropriately. Lesions of the brain that everyone agrees would be within the province of neurology (e.g., anoxic brain damage, encephalitis, lead poisoning) may cause mental symptoms or worsen and distort the symptoms of mania and schizophrenia. Patients with neurological diseases may have mental symptoms that are indistinguishable from those encountered
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in psychiatric disorders. The treatment of neurological diseases can produce cognitive and behavioral changes, the treatment of mental illnesses can produce neurological symptoms. Fortunately, history-taking and neurological examination encompass bedside techniques that provide sensitive and specific reflections of the functioning of the brain, and that can lead to a diagnosis. Unfortunately, for all psychiatric disorders and many neurological disorders, the history and physical neurological examination are the only tools for diagnosis.
The Importance of the Clinical History
Psychiatrists and neurologists encounter some of their most difficult diagnostic problems in differentiating disorders that are properly within the province of neurology from those that are best dealt with by psychiatry. Many patients have both neurological and psychiatric disorders. For example, when a patient with multiple sclerosis (MS) becomes depressed, certain questions should come to the clinician's mind such as the following:
There are no specific clinical criteria that would clearly distinguish one of the above etiologies from the other. Regardless of the etiology depression, a depressed patient looks like a patient. In fact, the similarity of the clinical picture of depression despite varying causes makes the diagnostic process in behavioral neurology intriguing and challenging. The fact that a diverse number of etiologies can cause the same symptoms is not surprising. The central nervous system, like other organ systems, has a limited repertoire of symptoms (Table 7-1).
The most important clues to the etiology of a patient's behavioral disturbances are past psychosocial and psychiatric history. Consider the depressed MS patient. If he or she has a history of excellent psychosocial functioning (e.g., good performance at work or school, the capacity to form friendships) and no history of psychiatric illness, we would be inclined to think that the depressive symptoms were probably caused by multiple sclerosis. If the patient has an extensive history of poor psychosocial functioning, a family history psychiatric illness and of past psychiatric disorders (particularly if the symptoms were similar
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to the current depressive symptoms), then we would be more likely to view the depressive symptoms as only coincidentally related to multiple sclerosis.
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Table 7-1 Mental Symptoms Seen in Brain Disorders |
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The seeds of a patient's presenting mental illness can usually be seen in past behavior. The exceptions are mania and other affective disorders. These can occur in mid or late life for the first time without any significant history of psychosocial dysfunction and without a history of previous psychiatric illness, though that is rare. In most cases, when the first onset of mental symptoms occurs after age 30, there must be a strong suspicion of neurological disease. The presence of any neurological findings on the physical or laboratory examination also increases the suspicion that a neurological disorder may be involved. Also developmental landmarks should be assessed during the clinical interview, as this will give some indication of early neurological impairment. This information can also put the patients current symptoms into perspective. Also to be assessed are maternal alcohol consumption or exposure to other neonatal toxins, that could lead to the fetal alcohol syndrome or other developmental problems. The sequelae of childhood learning disabilities can lead to subtle adult cognitive and behavioral impairments (Townes and Slade, 2000). In particular, the syndrome of nonverbal learning difficulties can often present a picture that looks
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as if the patient's problems are characterological e.g., apathetic, unmotivated, and unable to detect social cues, with normal IQ (Dugbarty, 2000).
The course of the symptoms is also important. Abrupt changes in personality, mood, or ability to function are much more typical of neurologic diseases than of psychiatric disorders. Also, rapid fluctuations of behavior or mental status are more likely caused by neurological disorders such as seizures, toxic-metabolic encephalopathy, delirium, or infection. In fact, any change in personality should raise the clinician's index of suspicion (even if the change is for the better). If a characteristically irritable and obsessive individual suddenly becomes placid or loses his obsessive traits (or the opposite), the clinician should consider possibility that some cerebral disturbance such as a tumor, hydrocephalus, or stroke has developed.
If symptoms are sudden in onset and gradually improve or stabilize, a stroke should be considered. If symptoms are asymmetrical and develop gradually, a tumor may be present. If symptoms are gradual in onset and diffuse, a degenerative disorder needs to be considered. Patients that have primarily behavioral symptoms that have been present for many years, most likely have a psychiatric disorder.
When a patient's symptoms do not quite fit the diagnostic criteria for the many disorders outlined in DSM-IV, a neurological disease may be the cause. Even though DSM-IV represents an arbitrary classification system, the classical descriptions of the major disorders such as mania, schizophrenia, etc, have been fairly consistent for over 100 years and when a patient fits the criteria diagnosis outlined in DSM-IV perfectly, than one can have confidence the diagnosis. It is when the patient's symptoms or clinical course do not fit or fit the diagnostic criteria poorly that we should become suspicious (Fig. 7-1).
Many clinicians invoke a psychiatric diagnosis when the patient's symptoms do not fit a neurological diagnostic category. The opposite also occurs. When a patient's behavior is abnormal but not typical of mental illnesses, one should think of neurological conditions that could cause it.
The duration of symptoms is an important criterion for diagnosing mental illnesses. Isolated or brief psychiatric symptoms may not signify a psychiatric disorder. Feeling sad following events that would make anyone is not a
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mental illness. The patient who is having trouble functioning and admits being sad and in a depressed mood nearly every day for at least several weeks, as well as having persistent sleep, appetite, and sexual disturbances, psychomotor slowing and feelings of worthlessness, guilt, or suicidal ideation, meets the full criteria for a major depressive disorder. Even if a patient does not meet the full DSM criteria for a major depressive reaction, however, it is still worth noting and following the depressive symptoms. For example, in a patient who has lost a spouse of many years, bereavement may last for 6 months to 1 year, but at times this normal process can become a major depressive reaction with many biologic symptoms such as sleep and appetite disturbances or psychomotor retardation. In the same way, a neurological patient can have mild depressive symptoms that may progress over time to a full major depressive disorder.
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Figure 7-1 Flowchart for differentiating psychiatric from neurological disorders. The starting point for differential diagnosis is the primary symptoms of central nervous system dysfunction (excluding a history of substance abuse). The primary symptoms of central nervous system dysfunction are also covered in Table 7-1. * Dementia is one of the main risk factors for delirium, so there may be an underlying dementia in delirious patients. ** Diagnostic evaluation must now include appropriate blood work, EEG, and imaging studies. |
Neurological Conditions Commonly Associated with A High Incidence of Psychiatric Complications
Many neurological conditions have an association with psychiatric disorders (Table 7-2), but it is often very difficult to separate preexisting psychopathology from current behavior (Popkin and Tucker, 1992; Brown et al., 1994). Still the origin of behavioral symptoms is the brain. If neurologic disease the brain coexists, it is likely that the behavioral symptoms also arise from same illness. The literature delineating associations between behavioral symptoms and neurological disorders consists mostly of case reports, where it is never clear whether the association is a chance occurrence or there strong relationship between the neurological disorder and a specific behavior. For example,Waxman and Geschwind (1975) reported three patients with seizure disorders who seemed to have specific interictal personality traits: hyposexuality, hypergraphia, and philosophical or religious interests. When large groups of patients with seizure disorders are studied, however, this constellation of symptoms is not prominent (Bear and Fedio, 1977; Mungas, 1982). Another problem is that the data often come from academic medical centers, which tend to serve skewed populations, e.g. atypical patients, treatment failures, or unusually complicated patients. The incidence of depression in patients with stroke (Robinson, 1998)) and Parkinson's disease (Mayeux et al., 1986) has usually been cited as 20 to 30 percent. These studies have come almost exclusively from university inpatient and outpatient services. When community surveys are carried out among patients with these conditions, the incidence and prevalence of depression is only slightly higher than in a normal population of comparable age (House et al., 1990; Tandberg et al., 1997).
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Table 7-2 Common Behavioral Conditions Associated with Neurological Illness |
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The Clinical Examination of the Brain
In addition to the history, the physical neurological examination can be confirmatory. Often it provides guidelines for further laboratory and diagnostic testing. The clinical examination should be used to test hypotheses about anatomic aspects of the patient's disorder that the history generated. The examination can determine whether there is a diffuse or a focal process and whether there peripheral nervous system and/or central nervous system involvement.
The neurological examination is a way of determining if various parts of the brain and spinal cord are functionally intact. It is easiest to test the lower, phylogenetically more primitive parts of the nervous system and then progress to more complex functions.
The human brain is organized in layers of interacting regions. At the base, just behind the mouth, is the brain stem, which controls most elemental functions
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such as breathing, blood pressure, and swallowing. It also controls the cranial nerves subserving eye movement, facial movement, and the muscles of the throat, mouth, and neck. The brain stem mediates sensation in the head, face, and neck and, through the cerebellum, general motor coordination. Above brain stem, behind the nose and its sinuses, is the diencephalon. This controls body temperature, appetite, sleep, and wakefulness. Circling around that central region of the brain is limbic system and amygdala-hippocampus complex, the seat of the primitive emotions involved in sexual behavior, fear, anger, and aggressive attack, as well memory. Virtually all mammals share these features.
Cortical Functions
Covering the entire surface of the brain stem, and lying just below skull, is the cerebral cortex, the thick layer of gray matter that is the source intelligence. The cortex is anatomically and functionally distinct from the rest of the brain. Complex perceptual and cognitive functions take place in the cortex. Vision registers and is integrated at the back of brain in occipital lobes. Somatosensory information like touch, pain, and position in space is interpreted in the parietal lobes; smell and taste in the temporal lobes. Speech the understanding of language are usually identified with the left posterior temporal lobe (Wernicke's area), and the actual expression of language comes from a posterior part of the left frontal lobe (Broca's area). Voluntary movement derives from the motor strip in the posterior part of frontal lobes. Voluntary movement is modified by deep subcortical centers called the basal ganglia. Almost all mammals have well-developed occipital, parietal, and temporal lobes as well as motor control systems that are very similar to the human ones.
To determine if the brain is intact, the examiner must test reflexes and sensorimotor functions, comparing the patient's right and left sides observing his stance and gait. The head circumference should be measured with a tape and compared with a table of normal standards. If the circumference is more than two standard deviations below the mean, patient is microcephalic and will have a 95 percent chance of being cognitively impaired.
Tests of motor coordination include skipping, hopping, and walking a straight line forward and backward. The patient should be asked to spread his fingers apart and hold his hands apart while the examiner looks for discontinuous, involuntary, jerky movements of the fingers and arms, called choreiform movements. The patient should be tested to see if he is right handed and footed. If dominance is mixed, it might mean that his nervous system has not developed the way that it should.
Abnormality on a single test usually does not mean that the person is brain damaged, but a pattern of abnormalities does indicate that the brain is malfunctioning.
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Asymmetrical (lateralized) abnormalities are likely to reflect structural abnormalities of the central nervous system, but severe damage to brain can be present in patients whose sensorimotor functions, coordination, and reflexes are normal.
Many psychiatric disorders manifest clinical neurological signs. Although this is of clinical and theoretical interest, it can complicate the interpretation the neurological findings. Neurological signs have been noted in 36 to 50 percent of schizophrenic patients. Some of these signs disappear when the patient's behavioral and cognitive symptoms have remitted (Tucker et al., 1974). Many of the neurological deficits observed in psychiatric patients relate to difficulties in sensory integrative functions, such as graphesthesia, stereognosis, and audiovisual integration; and to motor coordination, or movement sequencing, patterning.
Regressive reflexes, e.g., snout, suck, or grasp, nuchocephalic reflex, etc. (Jenkyn et al., 1977) are associated with diffuse cerebral dysfunctions (e.g., delirium, dementia). These reflexes are called “regressive” because they normally present in very young children and infants but not in adults. When regressive reflexes are observed in psychiatric patients one should investigate further and not attribute them to the psychiatric disorder. Aging (Jenkyn et al., 1985) and neuroleptic medications can cause regressive reflexes
Cognitive Functions
Given that the brain is the organ of cognition, cognitive functions must also be tested in the neurological exam. The Mini-Mental Status Examination (MMSE) is a standard tool for the screening of cognitive status (Task Force Handbook of Psychiatric Measures, 2000). Patients must be able to identify the day, date, time of day, and where they are. They should be asked to name several objects that have just been presented to them. Patients are given three words, asked to repeat the three words and to remember them; subtract 7 from 100 and to perform 5 serial subtractions of 7; to spell the word “world” forward and backward, and to recall the three words they were instructed to remember earlier. Patients must be able to read, repeat, write a sentence, copy standard diagram, and follow a three-step command.
Although the MMSE has gained wide acceptance as a clinical and research tool, other standardized evaluations have been developed for assessing cognitive dysfunction in specific neurological disorders e.g., The Dementia Rating Scale (DRS) and the Alzheimer's Disease Assessment Scale (ADAS) are widely used to quantify cognitive dysfunction in dementia patients; the Galveston Orientation and Amnesia Test (GOAT) for measuring amnesia and orientation; the DRS for quantifying the degree of delirium (Task Force for the Handbook Psychiatric Measures, 2000).
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Cummings et al. (1994) have developed the Neuropsychiatric Inventory (NPI) that assesses 10 behavioral domains (e.g., anxiety, agitation, depression, motor behavior, etc.) in patients with dementia.
Except for the behavioral measures, most of these tests assess similar functions of orientation, memory, calculation, reading, writing, and speaking. They are useful for uncovering evidence of damage to the posterior two-thirds brain, the parietal, temporal, and occipital lobes, for quantifying changes in the patients' conditions, but are insensitive tools for detecting damage and dysfunction of the frontal lobes even when they are severely damaged.
Behaviors Associated with the Frontal Lobes
The most obvious difference between the brains of humans and other primates is the size of the frontal lobes. The lobes humans are massive in relation to the other parts of cortex and account for about one third cortical mass. It is the job of the frontal lobes to organize motor and cognitive functions, to focus attention, make decisions, and to modify inhibit the behavioral impulses that surge up from the other parts of the brain. The frontal lobes permit us to check impulses, to say to ourselves, “No. Do not say or do that,” in response to our urges. The frontal lobes allow us to anticipate adverse or favorable circumstances, to care about the results, plan, invent, modify, and adapt in response to changes our environment. The frontal lobes provide social pragmatics, a good term provided by Jean Fryer, an expert in the rehabilitation of patients with traumatic brain damage (personal communication, 1999). The frontal lobes subserve judgment.
The clinical history is the most important element in the assessment of status of the frontal lobes. Frontally damaged individuals may not focus their attention for long periods of time and do not prioritize well. They are distractible. They may speak too loudly, stand too close, joke much, and make others feel uncomfortable. They have difficulty in gauging the effect that they are having on observers and do not seem to care. This defect in social pragmatics can be a major impediment to obtaining and holding jobs, maintaining relationships, and succeeding in life. Patients with frontal lobe damage may be with-drawn, apathetic, and mute most of the time, they may also be unable to control the expression of emotions such as irritation and sexual attraction. They may express thoughts and desires that their intact frontal lobes would have controlled, spending too much money, driving at excessively high speeds, or fighting. They often cannot keep their behavior within the general bounds of society.
With frontal damage some people become boastful, others irritable and argumentative, and still others calm apathetic. Some have no interest in sex, while others are hypersexual.
Wide fluctuations in mood and behavior can occur, erratically, in a short time
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unmodulated by the social brakes that the frontal lobes normally provide. When frontal injuries occur in persons with affective disorders, patients tend to have wider mood swings that occur more rapidly.
The frontal lobes can be damaged or even surgically removed without causing any abnormality in speech, arithmetic ability, reading, writing, or memory. Though these functions, tested by the MMSE and IQ tests, often remain intact after frontal lobe injury, profound and devastating changes can occur in the patient's social life.
The famous story of Phineas Gage exemplifies the kind deficits that frontal lobe injury can produce. Gage was a hard-working, reliable, ethical foreman who supervised a crew laying railroad tracks in New England around 1850. Gage set up the gunpowder used for blasting. He was injured when a premature explosion blew an iron rod through his frontal lobes. He recovered from the injury and could walk, talk, read, write, calculate, remember; however, he was a changed man. He could not hold job because he lost his ambition and initiative and became unreliable. He began to drink, swear, fight, and carouse. He became a derelict. Because of the traumatic injury to frontal lobes, he suddenly developed elements of what today would be called an antisocial personality disorder.
Evaluation of the Frontal Lobes
Fibers from the frontal lobes project to other regions of the brain such as corpus striatum and the dorsomedial nucleus of the thalamus. Lesions in dorsomedial thalamus can easily cause the kinds of abnormalities that frontal lesions can produce. For this reason it is a mistake to conceptualize the functions that are mediated by the frontal lobes as residing exclusively within this area of the brain, but for the sake of brevity, we will refer to them as frontal functions.
Judgment and the ability to deal with complexity are crucial functions of the frontal lobes. Unfortunately, there is no reliable, objective standard or test for measuring judgment that is sufficiently sensitive and specific. Asking a patient what he would do with a stamped addressed envelope found lying in a street is not an adequate test of frontal lobe function. It is insensitive and nonspecific. There are, however, several simple physical tests of frontal lobe function.
The most useful of these tests evaluates the frontal eye fields, the portion the frontal lobes that enables the eyes to track a moving object. The examiner asks the patient to follow examiner's smoothly moving finger as it goes slowly from left to right horizontally in front of the patient. An abnormal response would be visual tracking in brief, staccato, discontinuous jerks (saccades) or inattentiveness with brief deviations of the patient's eyes from the examiner's finger rather than smooth movements. A normal response would be smooth visual tracking of the moving finger. The patient should also be able to stare
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for 30 seconds at the examiner's stationary finger without deviating his gaze. This helps demonstrate his ability to concentrate.
Tapping gently on the bridge of a patient's nose normally elicits blinking. If the blinking persists for more than three taps, it means that the patient cannot accommodate to a benign stimulus. After three taps it should be clear that there is no potential threat to his eyes. If the patient cannot suppress the urge blink even though there is no threat, it shows that he cannot adapt to a new situation. This inflexibility reflects dysfunction in a frontally mediated pathway (Jenkyn et al., 1977)
Paying attention to two sensory stimuli simultaneously can be difficult for frontally damaged people. They tend to disregard the more distal of two unilaterally applied stimuli. For example, if the examiner touches the patient's right cheek and right hand simultaneously, while the patient's eyes are closed, the patient may report having been touched only on the cheek. This is called the face-hand test. If the patient extinguishes (pays no attention to) the more distal stimulus, it shows that his attention to somatosensory stimuli by the frontal lobes is attenuated.
To see if a patient can concentrate and suppress an urge, the examiner creates a visual urge and then asks the patient to ignore it. The examiner faces patient, holds his hands to either sides of the patient's eyes, and asks the patient to look at the examiner's nose. He instructs the patient to deviate his eyes the side of the examiner's briefly raised index finger and then return his gaze to the examiner's nose. Alternately, the examiner moves his right and then left index fingers. The patient looks toward the moving finger and then back at the examiner's nose. Once it is clear to the examiner that the patient has mastered this and looks to the moving finger and then back examiner's nose, the examiner asks the patient to look toward opposite side, toward side that does not move. Patients with frontal damage have trouble suppressing the urge to look at the moving finger and first there before correcting. This test uncovers impulsivity and inattentiveness. It is called the antisaccade test. performed five times, twice to the left, twice right, and then once left. More than one failure counts as an error.
Frontally damaged individuals often cannot perform two-and three-stepped motor sequences repetitively even though their strength and coordination are normal. This makes complex, repetitive motor tasks sensitive indicators of frontal function. The patient is asked to strike his thighs repeatedly, simultaneously, with the right palm and the left fist, then with fist and palm, alternating with each blow. He should be able to perform three sets perfectly on his own after having been taught how to perform this by the examiner. This is the two-stepped Luria test. Then the examiner shows patient how to strike his thigh successively with his right palm, fist, and the edge of his hand. The patient attempts this alone after he is shown how to do this by the examiner.
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The patient is then asked to perform this task with his left hand, striking the palm, the fist, and the side of the hand in sequence. This is called three-stepped Luria test. Frontal lesions often interfere with the proper sequencing of this task. Abnormality on either the two-or three-stepped Luria test indicates frontal dysfunction.
Patients with frontal disturbances often cannot relax their limbs when asked to do so and allow them to remain suspended in the air when one is raised and then dropped by the examiner. This is the placement test. Sometimes patients try to help by anticipating the position examiner wishes them assume after the examiner instructs them to be “limp as a rag doll.” The abnormality is called paratonia. It represents perseveration of resting tone; it melds into perseveration of movement as the patient overcomes initial inertia and gets into rhythm with the examiner's testing movements. When examiner releases patient's arm or leg, instead of dropping, relaxed to the bed, the limb remains suspended or continues in perseverative fashion carrying out the supposedly passive movements for testing tone that the examiner was employing (Reeves, 2001). When this sign is severely abnormal, the limb will remain in any position in which it was placed. This phenomenon is called waxy flexibility or catatonia and can also be encountered in psychotic states of depression and schizophrenia.
Upward gaze is another frontally mediated function. When asked to look upward, the individual should be able to move outer limbus of his iris upward at least 5 mm.
Testing the nuchocephalic reflex revels patient's ability to adapt postural change. It is often helpful in diagnosing frontal disease. With the patient's eyes closed, the examiner places his hands on the patient's shoulders and quickly turns him to the right or to the left. Normally, the head follows shoulders but maintains its posture through looking straight ahead. Some frontally impaired individuals do not move their heads with their shoulders but maintain the posture of their heads as though they were looking straight ahead. They cannot adapt to this postural change.
The snout reflex is tested when the examiner uses middle phalange of his flexed index finger and firmly presses the patient's relaxed lips and then draws his finger away. Any contraction of the orbicularis oris to this stimulus results in a puckering of the lips or chin. The suck reflex is similar. examiner firmly places the knuckle of his flexed index finger between subject's lips. There should be no response from either stimuli. Any pursing or sucking motion by the subject's lips or movement of his chin is recorded as a disinhibited reflex and an abnormal response.
The grasp reflex is tested both with and without distraction. First the patient is told to relax his hand while the examiner uses own finger to stroke its palmar surface of the patient's hand. Next the patient is distracted by being instructed to spell a simple word such as “fist” both forward and backward.
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Each hand is stroked without distraction and then with distraction. The addition of a second task (“spell ‘fist’ backward”) to the first task (“relax your hand”) increases the stress on the person and allows a disinhibited reflex to become manifest in frontal lobe dysfunction. Absence of any flexion of the subject's fingers is normal. Any flexion of the fingers represents disinhibition and is abnormal.
The results of each these tests are not abnormal in every case frontal damage. A pattern of abnormality, i.e., three or more abnormal tests, sustains the conclusion that the frontal lobes are damaged. Three abnormal tests reliably correlate with abnormalities in both the MRI of the brain and neuropsychological testing with the Halstead-Reitan battery (Jenkyn et al., 1977; Jenkyn et al., 1985; Blake et al., 1995; Bae et al., 1998).
The correlation is significant but not absolute. We have found that the most sensitive and specific of these frontal neurological tests are the inability to perform smooth visual pursuit and the inability to perform accurately the three-step Luria test. Magnetic resonance imaging scans of patients who fail both these tests are likely to be abnormal.
The abnormalities on these tests are age-dependent. They may not be abnormal if found in preschool children. Unfortunately, there are no studies of normal children that indicate at what age a “frontal sign” is abnormal.
Many of the frontal signs can be seen in older patients, and the accompany Parkinson's disease, chorea, and they can also be seen in patients who are receiving drugs that block dopamine receptors. Many of these signs may also be encountered in schizophrenics. Whether they reflect abnormalities of the brain that are induced by schizophrenia or are comorbid with the disease caused by medication is uncertain. It is not known whether abnormalities on the frontal tests described above can distinguish a patient who has frontotemporal dementia from the pseudodementia of depression. The successful treatment depression may reverse some frontal signs, but this has not been systematically studied.
Cognitive aspects of the frontal lobe evaluation
The word fluency test examines frontal function by testing the ability to generate words that are not in a context. In this test, the examiner asks patient to name as many words he can in 60 seconds that begin with either the letter “F” or “M.” A normal score is 14 plus or minus 5. It is abnormal to name fewer than 9 words. This is not an intelligence test but a test of improvisation. A person with frontal damage might perform normally on an I.Q. test or MMSE. Because frontally damaged people have trouble improvising or in using old knowledge in a new way, the word fluency test provides an indication of frontal dysfunction.
The “king story” can be very useful in separating patients with attentional deficits from those with memory deficits. The story has a familiar sound but contains no familiar details:
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Once upon a time there lived king who was very ill. His physicians could not help him so he sought the advice of his wise men. His men advised to obtain the shirt of a happy man. The king sent out messengers who scoured kingdom and finally found a happy man, but the man did not own a shirt.
Before this story is recited the patient asked to pay close attention the details and then to repeat the story, including as many details possible. When patients are unable to provide all the details of this story, it indicates inattention. Sometimes the inattention is the result of frontal damage and sometimes it reflects nervousness, depression, mania, schizophrenia, obsessiveness, or intoxication. After the examination has been completed and 15 minutes have elapsed, the patient is asked to repeat the story. If the recalls 75 percent of the details that he included in his initial repetition of the story, the examiner can conclude that the patient's memory is intact. The combination of poor attention span and intact memory is frequently seen in patients with frontal dysfunction.
The psychological tests that most reliably reflect frontal dysfunction deal with executive functions that are mediated in large part through the frontal lobes. The most sensitive tests are the Wisconsin Card Sorting Test (WCST), Trail-Making Tests A and B, the Categories subtest of the Halstead-Reitan battery, and tests of continuous performance such as the Stroop Color and Word Test (Golden). None of these psychological tests is 100 percent predictive the existence frontal lobe damage as determined by MRI or the neurological examination, but a neuropsychological assessment for suspected frontal lobe damage that does not include the WCST, Trail-Making, Categories, and continuous motor performance is incomplete (Lezak, 1995).
Mental Status Examination
The mental status examination traditionally practiced by psychiatrists is little more than a way of organizing information. The traditional format (divided into appearance and behavior, mood affect, language thought, cognition, volition, suicide and homicide tendencies, judgment) is the way an experienced psychiatrist will organize his or her observations of the patient's mental functions (Trzepacz and Baker, 1993). However, it often leaves one without knowledge of whether certain functions were assessed, or they were omitted because the patient could not perform them. The other major drawback of this type of examination is the lack sufficient quantifiable data for comparing one patient to another, as well the same patient's mental functions over time. Consequently many clinicians include standardized scales of cognitive function and behavior such as the MMSE the NPI (see pp. 257–258) part of their mental status examination.
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Imaging
With the data now available from computerization of radiologic procedures and MRI, we are able to correlate observed behavior and performance on neuropsychological testing with the actual visualization of lesions in the central nervous system. The computerized axial tomography scan uses X-rays to produce excellent transverse images of the brain and is particularly useful for detecting meningeal and parenchymal abnormalities associated with metastatic neoplasia or inflammatory conditions as it measures tissue density. It is also very useful for finding calcified lesions, acute subarachnoid bleeding, and intracerebral hemorrhage. In general, however, MRI provides superior resolution. Though MRI is not sensitive to bone or to calcified lesions, it is particularly useful in detecting tumors, scars, and strokes as it delineates differences in the boundaries of tissue and fluid better than CT. Consequently it is superior to CT for evaluating the temporal lobes, subcortical structures, cerebellum, brain stem, and spinal cord. Magnetic resonance imaging is also much better in detecting white matter lesions, such as those associated with multiple sclerosis and microvascular disease (Hurley et al., 1997).
Another great advantage of MRI is the ability to obtain not only structural data but also functional data. During the MRI, a pulse of energy (a particular radio frequency) applied to the atomic nuclei in the brain (usually the hydrogen ion) generates a deflection pulse. From these pulses one can measure proton density, which in turn reflects the density of the hydrogen nuclei. Two measures give further information. The first, which is known as time constant one (T-l), is a measure of the relaxation hydrogen nuclei in a longitudinal plane. The second is spin relaxation (T-2), which a measure in the transverse plane. These reflect in part the relationship of free water and lipids the tissue. Magnetic resonance imaging series weighted between T-l and T-2 can also be performed—and also reconstructed via computers retrospectively. This provides great detail, showing, for example, the anatomical boundaries of white and gray matter. It also has the potential for functional studies by demonstrating physiochemical differences in different brain regions.
With a variety of software programs, the MRI can provide arteriograms and venograms. It can detect edema and hemosiderin (evidence of past hemorrhage) within the brain, as well indications of neural activity called functional MRI (FMRI). Most exciting has been the development of MR spectroscopy (MRS) to obtain assessment of various chemical structures within the working brain with great detail (Kortola, 1997).
The use of imaging technologies in psychiatric patients is certainly indicated when there are localizing neurological findings or a history suggesting neurologic causes like unexpected confusion, sudden cognitive decline, dementia, movement disorder, psychosis of abrupt onset, anorexia, catatonia, late onset
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affective or personality disturbances, and atypical symptoms in the course of chronic psychiatric illness (Weinberger, 1984; Hurley et al., 1997). Beresford et al. (1986) found high correlations, between positive findings on CT scan and abnormal cognitive examination. Often, patients with normal CT scans end up with an MRI of the head as the index of suspicion warrants further confirmation of the absence of structural pathology. Except for emergency room screening and demonstrating hemorrhage or calcium, MRI (when available) has eclipsed CT in the practice of neurology and psychiatry.
Other dynamic measures—such as PET, SPECT—are valuable for defining the functional areas of either hyperor hypoactivity as well measuring regional cerebral blood flow and have been useful for the diagnosis of dementia (Charpentier et al., 2000). Position emission tomography also has the potential for localizing various neurotransmitter receptors. These techniques are being used in research and are not really routine clinical use.
Clinical Laboratory Tests
The brain can be disordered by conditions whose presence only be detected by examinations of body fluids—namely, endocrine, infectious, metabolic, and toxic disorders. These conditions generally require investigation by blood tests such as complete blood count, sedimentation rate, urea, electrolytes, glucose, syphilis, HIV, and endocrine functions. B12, folate, calcium, phosphorus, magnesium, porphyrin screens, antinuclear antibodies, and other laboratory tests may be required as clinically indicated. Lumbar punctures have become less necessary as imaging has improved, but suspected inflammatory conditions still require cerebrospinal fluid examination for diagnosis.
Electroencephalography
The electroencephalogram (EEG) has been used widely in both neurology and psychiatry in disorders with an episodic course. Patients who have repeated episodes of disturbed behaviors who have paroxysmal spikes or spikes and waves on the electroencephalogram often have epileptic seizures. However mentally ill patients rarely manifest paroxysmal episodes of spikes. When they do, it often reflects a medication effect. However, if the patient with these paroxysmal spikes “due to medication effects,” does not respond well psychopharmacological management then a trial of anticonvulsants maybe in order. The EEG is also useful for detecting focal abnormalities, particularly when they occur in the temporal lobes (Tucker, 1998). Such abnormalities are most often dysrhythmic, slowed, nonparoxysmal, i.e., nonspecific, patterns. Again if a patient
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is not responding to treatment with standard antipsychotic or antidepressant drugs, a trial of anticonvulsants may be usefully tried, especially if the EEG is abnormal.
Normal EEG results do not exclude the existence of a brain disorder. Scalp electrodes may make it difficult to localize symptoms because symptoms originating from deep structures such as the mesial temporal areas may not be identified by surface electrodes. Even with depth electrodes, recording may be falsely negative because the placements have to be in exactly areas associated with firing. Sleep EEG records significantly increase the likelihood of finding EEG abnormalities, particularly focal lesions such as temporal lobe lesions.
Conclusion
The most powerful diagnostic instrument in the evaluation of patient with possible brain damage is a detailed history of the presenting symptoms and the patient's developmental history. The clinical evaluation should include a full physical, a comprehensive neurological, and a detailed evaluation of cognitive and cortical functions. The history and examinations will usually allow a preliminary diagnosis or at least point the way toward further evaluations necessary to make a diagnosis. After detailed clinical examination one usually has a good idea about the nature of the problem. Usually blood and urine tests, waking and sleep EEGs, imaging studies, and neuropsychological assessment consolidate the clinical impression. Rarely are all tests abnormal. The abnormal, not the normal, test is definitive. No single test can reliably identify normal brain function. The patient who presents with a mixture of behavioral and neurological symptoms is a challenging clinical problem. Often the diagnosis does not fit into neat categorization. Sometimes the diagnosis will only become clear over time. The borderland between neurology and psychiatry remains, even in this era of high technology, a place where knowledgeable and careful physician is still the crucial diagnostic instrument.
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