TIA-like presentations of cerebral amyloid angiopathy

Abstract

Transient focal neurological episodes (TFNEs ) are transient ischemic attack (TIA)-like episodes that may occur in patients with cerebral amyloid angiopathy (CAA). The duration of TFNEs is typically similar to TIAs with most symptoms resolving in minutes. Symptoms, similar to those of TIAs include sensory or visual disturbances, motor weakness and language impairment and there may be limb jerking or associated headache. TFNEs have a more gradual onset and tend to spread slowly to contiguous body parts like a migraine aura. TFNEs may occur repeatedly throughout the day and attacks may continue over several months. TFNEs are typically associated with focal cortical subarachnoid hemorrhage or with focal cortical superficial siderosis. They may also be seen in patients with CAA-related lobar hemorrhage, microhemorrhage or leukoencephalopathy. Migraine prophylactic agents such as verapamil and topiramate may be useful in stopping frequent recurrent TFNEs. TFNEs are an under-recognized cause of apparent TIAs. It is important to keep TFNEs in the differential diagnosis when a patient presents with a presumed TIA as thrombolysis or anticoagulation is relatively contraindicated in CAA. Gradient echo MRI should be performed to exclude microhemorrhages when TFNEs are suspected.

Clinicians most frequently associate cerebral amyloid angiopathy (CAA) with intracerebral hemorrhage or with a clinical picture of vascular cognitive impairment.1 There have however, been increasing clinical reports documenting that CAA may cause a variety of acute clinical neurological manifestations.2 Although these phenomena are superficially similar to TIAs and may be mistaken for them, they have clinical time profiles and progressions that can distinguish them from TIAs clinically. They appear to be caused by different manifestations of the complications of CAA and are now known as transient focal neurological episodes (TFNE).2,3

CAA frequency increases with age with approximately 50 % of individuals over the age of 75 being affected. The exact cause of CAA remains uncertain however increased production and/or decreased breakdown of amyloid proteins may have a role. CAA predominantly affects occipital regions of the brain followed by frontal and temporal areas. Cerebellar vessels are less commonly affected.3The Boston criteria is the current standard criteria for diagnosis of CAA. In this review, we attempt to classify and describe the different causes of TFNE’s in CAA.