Evaluation Guidelines Table163

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Neuroimaging. Many of the primary neurodegenerative movement disorders, whether hypokinetic or hyperkinetic, show no abnormalities on magnetic resonance imaging (MRI) or computed tomography (CT) scans other than mild to moderate cerebral atrophy. However, in

TABLE 16-3 -- USEFUL STUDES I

N THE EVALUATION OF HYPOKINESIA AND HYPERKINESIA SYN

DROMES

Syndrome

Neuroimaging

Electrophysiology

Fluid and Tissue Analysis

Neuropsychological Test

HYPOKINESIA

Pure parkinsonism

In Parkinson's disease, MR and CT are normal. PET scans of F-dopa can show decreased uptake

Usually not used. Can study tremor with tremorometer

Copper, ceruloplasmin and thyroid

Can detect depression, dementia

Parkinsonism-plus syndromes

In multiple system atrophy putamen can have hyperdensity in T2-weighted images. SPECT scans can show decreased activity in frontal parietal lobe

Rectal EMG may be useful in multiple system atrophy

In multiple system atrophy catechlolamines can be studied dementia patterns

Can detect evidence of dyspraxxia, aphasia, cortical or subcortical

HYPERKINESIA

Postural tremor

Normal

Tremor can be studied with tremorometer

Thyroid, drug 1eve1s esp lithium, amphetamines and tricyclic antidepressants

Not usually useful

Action-endpoint tremor

May show cerebellar white matter lesions

Evoked potentials may show evidence of widespread white matter disease as in multiple sclerosis

Lithium level. CSF can be studied for multiple sclerosis

Not usually useful. Pseudobulbar affect can be seen with multiple sclerosis

Chorea, choreothetosis and balism

In Huntington's disease, there is reduced volume of caudate nucleus Generalized cerebral atrophy

Not usually useful

Acanthocytes by fresh red blood smear, thyroid, drug levels of anticonvulsants

Genetic testing for Huntington's disease

Dementia can be detected, along with impulsive behavior and depression

Tics and stereotypies

Normal

Not usually useful

None used

Attention deficit disorder and obsessive compulsive behaviors are frequent problems in tic patients

Dystonia

Normal, can have lesion in putamen in some forms of secondary dystonia

Not usually useful except EMG is often used to guide botulinum toxin injections for theraphy

Blood test now can identify gene in idiopathic torsion dystonia

Depression and pain can be important contributors to disability

Akathisia

Normal

Not useful

Not useful

Patients can be psychotic, depressed, and anxious

Myoclonus

Usually normal. In postanoxic mycolonus, there may be diffuse cortical and subcortical damage

EEC helps detect seizures.

Also can show diffuse slow wave activity in encephalopathies research centers, back-averaging techniques can study origin of myoclonus

Electrolytes, calcium magnesium, thyroid function for metabolic causes of myoclonus

Dementia, difficulties concentrating

CSF, Cerebrospin fluid; CT, computed tomography; EMG, electromyography; F-dopa, fluorodopa; MRI, magnetic resonance imaging; PET, positron-emission tomography; SPECT, single photon emission computed tomography.

CSF, Cerebrospin fluid; CT, computed tomography; EMG, electromyography; F-dopa, fluorodopa; MRI, magnetic resonance imaging; PET, positron-emission tomography; SPECT, single photon emission computed tomography.

Huntington's disease, there may be focal atrophy of the caudate nucleus, leading to the appearance of enlarged lateral ventricles, without a comparable increase in size of the temporal horns. Similarly, in multiple system atrophy of the olivopontocerebellar type, localized atrophy of the pons and cerebellum may be prominent. In cases of hypokinesia, when the MRI scan shows increased signal intensity in the putamen on T2-weighted images, local iron deposition and the diagnosis of multiple system atrophy are suggested. MRI and CT scans are particularly useful in disclosing nondegenerative, secondary causes of movement disorders. Cerebrovascular accidents, abscesses, and tumors can be identified, as well as calcium deposition that may suggest parathyroid disease, old hemorrhage, or infections. Hypokinesia caused by carbon monoxide intoxication likewise has a characteristic pattern of cystic degeneration of the globus pallidus. Other neuroimaging techniques may prove useful in particular situations, such as single photon emission computed tomography (SPECT) scanning in corticobasal ganglionic degeneration, in which focal parietal lobe hypoactivity can sometimes be detected. Positron-emission tomography (PET) scanning with the use of selective ligands is used extensively in research centers to monitor patients with hypokinesia and hyperkinesia, but it is not used in a regular clinical setting (see Chapter^? and Cha.pter.34.).

Electrophysiology. Electroencephalography (EEG) is useful in studying any intermittent movement disorder, but the recording obtained must include episodes of the patient's movements in order to determine if there is a cortical event that occurs simultaneously. Cases of paroxysmal dyskinesias can sometimes be associated with epileptiform discharges in the contralateral frontal cortical region, and although they may not be detected in a standard EEG, double-density electrodes may provide the phase-reversal indicative of a seizure. In myoclonic disorders, EEG testing is important for documentation of a possible associated cortical event at the time of the myoclonic jerk detected by electromyography (EMG). Sensory evoked potentials and specialized computerized back-averaging techniques can be used with simultaneous EMG to clarify the brain stem or cortical origins. Tremors can be characterized with tremorometer recordings applied over agonist and antagonist muscle groups. In the evaluation of dystonic patients who will receive injections of botulinum toxin (see Chapter.34 ), the muscles maximally involved in the spasms can be identified with EMG needle recordings at the time of the injection. A variety of research electrophysiological tests are used for the study of movement disorders and their quantification, but these tests are largely restricted to specialty centers.

Fluid and Tissue Analysis. Few blood and urine tests are of primary interest in the characterization of movement disorders. Basic electrolytes, complete blood count (CBC), liver function tests, and thyroid function tests are standard tests that can be helpful screens. In cases of dystonia or tremor in which the specific condition known as Wilson's disease is considered, 24-hour urine levels of copper excretion and serum ceruloplasmin levels are useful. In specific cases, blood ammonia levels, coagulation profiles, or blood viscosity can be analyzed. In cases of chorea, unusual tics, or dystonic movement, fresh blood smear analysis for acanthocytes can be diagnostic. Childhood aminoacidopathies or other metabolic disorders with hypokinesia or hyperkinesias are diagnosed with specialized tests for enzyme levels or storage compounds found in blood, urine, or various biopsy tissues (see Ch.apter.3.0 and Chapter.?.! ). For a growing number of genetic illnesses with movement disorders that include Huntington's disease, generalized torsion dystonia, and dentatorubral-pallidoluysian atrophy, genetic tests can be diagnostic. In cases of acute onset of disorders, a toxicology screen is essential.

Cerebrospinal Fluid. Whereas alterations in various neurochemical metabolites like homovanillic acid (dopamine) and 5-hydroxyindolacetic acid (serotonin) are of research interest in various movement disorders, their levels are neither diagnostic nor useful specifically in dealing with disease progression.

Neuropsychological Tests. These tests help document cognitive and affective dysfunction that can be useful in determining diagnoses like Huntington's disease and also in guiding potential decisions regarding medical therapy. For example, when movement disorders are associated with depression or dementia, drugs that are associated with side effects like depression, confusion, or psychosis need to be avoided or used in reduced doses. Some movement disorders commonly co-exist with specific types of behavioral patterns, for example Gilles de la Tourette syndrome and attention deficit disorder or obsessive-compulsive disorder, and neuropsychological evaluations complement the neurological examination in identifying such combinations.

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