25.1 Clinical History – Main Complaint

An 83-year-old, right-handed woman with behavioral changes for 2 days was seen at the neurology outpatient clinic of Phramongkutklao hospital.

25.2 General History

Twelve days prior to the visit, the patient was manifesting behavioral and personality changes, which can be characterized by irritability, talkativeness, and paranoia. She had false beliefs that her grandchildren and neighbors burglarized her home and that her brother stole her land. Furthermore, her recent memory had declined. She repeated questions and was unable to remember the meals that she had eaten and where she placed things.

Ten days earlier, her symptoms were getting worse. Her mood became more aggressive. She had difficulty in some routine functions, such as grocery shopping; she lost interest in cooking, which she used to enjoy doing. Her basic daily living activities remained unremarkable. No headache, fever, motor weakness, speech problem, ataxia, or hallucination was observed. She denied medical illness in the past. She had no history of smoking, drinking, or using any medication. Her education level was primary school. The patient visited a private hospital and was referred to Phramongkutklao hospital.

25.3 Family History

Her parents passed away when she was young. She has an elder sister who was diagnosed with ischemic stroke at the age of 60. The patient has three children who are healthy. No family history of neurodegenerative or psychiatric problems is known.

25.4 Examination

She was alert and cooperative during the examination, but appeared to be irritable and angry in mood. Vital signs showed regular pulse rate of 90 bpm and blood pressure of 110/60 mmHg. Physical examination was unremarkable, including the cardiovascular system. Neurological examination revealed normal cranial nerves. In the motor examination, the patient had no abnormal movement, posture, or fasciculation. Her tone was normal. She had full proximal and distal strength: 5/5 throughout all four extremities. No cortical lobe signs, frontal lobe releasing signs, or neglect was observed. Sensory examination was intact position, vibration, and pinprick sensation. The reflexes were 2+ and symmetrical with no evidence of clonus. Plantar responses were flexor. Coordination examination was intact with no evidence of dysdiadokinesis, intention tremor, heel-to–knee, or positive rebound. Her gait was normal and the Rhomberg test was unremarkable.

On the Montreal Cognitive Assessment (MoCA) she scored 8/30. She lost five points in executive/visuospatial; two points in naming, number “1” tapping test, and letter fluency; three points in calculation; five points in delayed recall; and five points in orientation. On the Geriatric Depression Scale (GDS), the patient scored 2/15. This demonstrated that she did not have depression. Clinical dementia rating (CDR) scale was evaluated and her rating was 1. On the Instrumental Activities of Daily Living (IADL) Questionnaire with score range 0–8, where a lower score indicates a higher level of dependence, she scored 1.

25.5 Special Studies

Routine blood tests were done. Most of them were negative, except for complete blood count, which showed Hb 14.2 g/dL, Hct 45.1%, WBC 11,600 /uL, PMN 72%, lymphocyte 20%, monocyte 3%, eosinophil 2%, basophil 3%, and platelet 623,000 /uL. Peripheral blood smear confirmed thrombocytosis: platelet counts were 30–40 per oil field. Investigations were done and found positive for JAK2 V617F gene mutation. Electrocardiogram (EKG) demonstrated normal sinus rhythm. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) of the brain showed restricted diffusion in diffuse weight imaging at the left temporo-occipital and thalamus. MRA showed focal stenosis of the left posterior cerebral artery. Internal carotid arteries, middle cerebral arteries, and anterior cerebral arteries were normal (Figure 25.1).

25.6 Diagnosis

The provisional diagnosis was vascular dementia, strategic infarction subtype, based on the combination of acute behavioral changes, cognitive decline, and MRI findings compatible with acute cerebral infarction at the left thalamus. In general, the common causes of stroke are cardioembolic, atherothrombotic, and lacunar infarction. However, the etiology of stroke in our patient was explained by essential thrombocytosis (ET) from the JAK2 V617F gene mutation, which has been infrequently reported.

Essential thrombocytosis is a chronic myeloproliferative disorder in which clonal hematopoietic stem cell disorder causes an abnormal increase in the amount of megakaryocytes, which results in an increase in the amount of platelets produced. The concomitant thrombotic events include abnormalities in macrovascular circulation, such as cerebrovascular, coronary, and peripheral arterial disease, and in microvascular circulation, such as erythromelalgia, ocular migraine, and transient ischemic attack (TIA). In a study of 1,099 first-stroke patients, essential thrombocythemia is associated with ischemic stroke in 0.54% of the cases.¹ This group accounted for 42.8% of all hematologic disorders associated with ischemic stroke and represented 12.5% of the patients diagnosed with essential thrombocythemia during the study period.

25.7 Follow-Up

The patient has been followed up every 3 months. Atypical antipsychotic and antiplatelet drugs along with donepezil were given to control her symptoms. However, low performance in activities of daily living, delusion, and aggressive behaviors remained persistent. Thrombocytosis is well controlled by hydroxyurea.