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A comparison of risk factors for recurrent TIA and stroke in patients diagnosed with TIA

To the Editor: We congratulate Johnston et al. on their study of risk factors for recurrent cerebral ischemic events in patients presenting with transient ischemic attack (TIA).1 The authors focus on a distinct subgroup of patients with isolated sensory symptoms with a high risk of recurrent TIA (40%), not progressing to stroke. However, the syndrome of recurrent pure sensory episodes has been documented.2,3 C. Miller Fisher pioneered its description (the authors cite Fisher’s paper on late life migraine accompaniments, but not on this entity). In a series of 135 cases, Fisher found that isolated unilateral sensory disturbance presented in two distinct and equally frequent manners: (1) sudden onset of pure sensory stroke preceded by no or few TIAs; and (2) frequent transient, unilateral hypoesthesia or paresthesias not progressing to permanent deficit.2 The syndrome of recurrent pure sensory episodes has been associated with ventroposterolateral infarcts on imaging and autopsy.2,3 Its pathogenesis is speculative, but it is likely that a substantial proportion of cases are attributable to waxing/waning poststroke paresthesias as a variant manifestation of poststroke pain, and others to recurrent ischemia beyond a fixed stenosis in a penetrating vessel, migrainous phenomena, hyperventilation paresthesias, and simple partial seizures. Approximately three to five patients a year are referred to our stroke center for sensory spells that recur despite multiple combinations of antithrombotics and anticonvulsants. Making the diagnosis spares patients from repeated invasive imaging, treatment with aggressive combination antithrombotic regimens likely to produce bleeding complications, and undue worry when episodes recur.