Evaluating the Remote Effects of Stroke With MRI and PET Scans
Evaluating the Remote Effects of Stroke With MRI and PET Scans
Patients with stroke sometimes have a condition called diaschisis, a loss of function in a
 part of the brain located some distance from the original stroke-injury site. Doctors do not
 know why this happens.

 The purpose of this study is to get a better understanding as to why diaschisis occurs by
 studying people who have experienced a stroke and people who have aged in good health.

 Forty-four participants who are older than 40 year of age will be enrolled in this study-18
 healthy people and 26 stroke patients. They will have 3 to 4 study visits. The first visit
 will involve a medical history and a physical and neurological exam. Participants will then
 have a magnetic resonance imaging (MRI) scan, either on the first visit or on a later day. On
 the next visit, they will undergo a position emission tomography (PET) scan. Finally, they
 will return for another MRI scan.
Objective: Following a stroke, not only is there dysfunction of the lesioned area, but there
 is also remote functional depression of non-lesioned areas. This functional depression,
 called diaschisis, likely contributes to the functional deficit of the patient.

 The objective of this study is to obtain a better understanding of the pathophysiology of
 diaschisis with the integrated methods of neuroimaging (positron emission tomography (PET)
 and proton magnetic resonance spectroscopy (H-MRS)).

 Study population: We will recruit patients with subcortical stroke in the subacute state and
 in the chronic state, and normal controls.

 Design: The stroke lesion will be the basal ganglia, internal capsule, thalamus, or
 cerebellum. The frontal cortex, including the motor cortex, is chosen as a remote area.
 Neurochemical changes in the diaschitic area will be investigated by measuring the glucose
 metabolic rate with PET, and concentrations of neurochemically important metabolites, such as
 gamma-aminobutyric acid (GABA) and glutamate, with H-MRS.

 Outcome measures: Metabolic change in the diaschitic areas relative to the contra-lateral
 unaffected side will be calculated as a laterality index. First, this index will be compared
 among patient groups and control group. As a second analysis, the relationship of glucose
 metabolism measured by PET and concentrations of the metabolites detected by H-MRS will be
 evaluated.
-  INCLUSION CRITERIA:

 Patients will have a clinically and radiologically documented stroke in the subacute (2
 weeks to 6 months to after onset) or the chronic state (more than 6 months after onset),
 having a lesion in subcortical regions including the basal ganglia, thalamus, internal
 capsule, or a combination of these structures, or cerebellum unilaterally. These lesions
 can extend to the surrounding areas, however not including the cerebral areas where H-MRS
 ROI will be located. Both ischemic infarction and hemorrhage will be included; however, in
 cases of hemorrhage, we will exclude cases with deformation in the cerebral hemisphere due
 to mass effect of the hemorrhage, hydrocephalus, or extension to the ventricles. Patients
 will be 18 years of age or older.

 Healthy controls entering the study must be free of serious somatic disease as determined
 by a standard physical and neurological examination. Controls will be aged over 18 years.

 Female patients and controls of child bearing potential will have a pregnancy test and
 specific interview prior to the study to ensure that pregnant patients will not participate
 in the study. Both patients and controls will be asked to abstain from alcohol for one week
 before each of the PET and H-MRS scans.

 EXCLUSION CRITERIA:

 A. Patients with MRI findings consistent with brain tumors, trauma or AVMs will be
 excluded.

 B. Patients with multiple stroke lesions will be excluded, except for prior asymptomatic
 lacunar infarctions or stroke lesions which are not known to cause diaschisis in the
 frontal cortex (occipital cortex).

 C. Patients with severe stenosis (greater than 70%) or occlusion in internal cervical
 arteries and in the proximal portions of middle or frontal cerebral arteries detected by
 angiography or MRA will be excluded. Subjects with medical disorders which can affect the
 concentration of cerebral metabolites, including renal failure, hepatic failure and
 untreated electrolyte abnormality will be excluded. Subjects with poorly controlled
 diabetes mellitus (casual plasma glucose concentration greater than or equal to 200 mg per
 dL (11.1 mmol per L) or fast plasma glucose concentration greater than or equal to 126 mg
 per dL (7.0 mmol per L) will be excluded. Subjects who are taking sleeping drugs or
 tranquilizers will be asked to stop taking them for two days prior to each of the PET and
 H-MRS scans.

 D. Subjects with a pre-stroke history of schizophrenia or bipolar disorders will be
 excluded.

 E. Subjects with implanted devices such as pacemakers, medication pumps or defibrillators,
 metal in the cranium except mouth, intracardiac lines, history of shrapnel injury or any
 other condition/device that may be contraindicated or prevent the acquisition of MRI.

 F. Subjects with cancer will be excluded.

 G. Patients not capable of giving an informed consent will be excluded

 H. Ethnic origin and race will not be biased for inclusion.

 Participation of children:

 Children will be excluded from the study because we need to study a homogeneous group of
 subjects by age and developmental changes in metabolites will complicate this study.
 Additionally, young children will not be sufficiently cooperative for the long periods of
 testing. Moreover, the radiation dose of the PET studies would subject them to relatively
 greater risk than the adults.