Differential Diagnosis of Nervous System Disorders
= brief episode of transient focal neurological deficit ← ischemia of <24 hours duration with return to pre-attack status
Incidence: 31÷100,000 population per year; increasing with age; 105,000 new cases per year in USA; M >F
Cause:
- embolic: usually from ulcerated plaque at carotid bifurcation
- hemodynamic: fall in perfusion pressure distal to a high-grade stenosis / occlusion
Risk factors:
- Hypertension → linear increase in probability of stroke with increase in diastolic blood pressure
- Cardiac disorders: prior myocardial infarction, angina pectoris, valvular heart disease, dysrhythmia, CHF
- Diabetes mellitus
- Cigarette smoking (weak risk factor)
Prognosis: 5.3% stroke rate per year for 5 years after first TIA; per year 12% increase of stroke / myocardial infarction / death; completed stroke in 5% (33%) within (1 month) 5 years
Rx:
- Carotid endarterectomy (1% mortality, 5% stroke)
- prophylactic carotid endarterectomy + chronic low-dose aspirin therapy in patients with recently symptomatic TIA / minor stroke + >70% carotid artery stenosis
- Anticoagulation
- Antiplatelet agent: aspirin, ticlopidine (Ticlid®)
Carotid Transitory Ischemic Attack (~ 66%) 
- carotid attacks <6 hours in 90%
- transient weakness / sensory dysfunction CLASSICALLY in
- hand / face with embolic event
- proximal arm + lower extremity with hemodynamic event (located to watershed area)
- motor dysfunction = weakness, paralysis, clumsiness of one / both limbs on same side
- sensory alteration = numbness, loss of sensation, paresthesia of one / both limbs on same side
- speech / language disturbance = difficulty in speaking (dys- / aphasia) / writing, in comprehension of language / reading / performing calculations
- visual disturbance = loss of vision in one eye, homonymous hemianopia, amaurosis fugax
- paresis (mono-, hemiparesis) in 61%
- paresthesia (mono-, hemiparesthesia) in 57%
- amaurosis fugax (= transient premonitory attack of impaired vision due to retinal ischemia) in 12% ← transient hypotension or emboli of platelets / cholesterol crystals, (which may be revealed by funduscopy)
- facial paresthesia in 30%
Vertebrobasilar Transient Ischemic Attack (~ 33%)
- vertebrobasilar events <2 hours in 90%
- motor dysfunction = as with carotid TIA but sometimes changing from side to side including quadriplegia, diplopia, dysarthria, dysphagia
- sensory alteration = as with carotid TIA usually involving one / both sides of face / mouth / tongue
- visual loss = as with carotid TIA including uni- / bilateral homonymous hemianopia
- disequilibrium of gait / postural disturbance, ataxia, imbalance / unsteadiness
- drop attack = sudden fall to the ground without loss of consciousness
- binocular visual disturbance in 57%; vertigo in 50%
- paresthesia in 40%; diplopia in 38%; ataxia in 33%
- paresis in 33%; headaches in 25%; seizures in 1.5%
= repeated periodic events of neurologic dysfunction with complete recovery to normal in interphase