Reversible ischemic neurological deficit is a type of stroke due to the occlusion of blood supply to the brain leading to ischemia and neurological deficits which recover from 24 hours and up to a few weeks. It should be differentiated from a transient ischemic attack in which the neurological deficits do not last longer than a day. However, currently the term reversible ischemic neurological deficit is rarely used.
Reversible ischemic neurological deficit (RIND) is defined as a stroke due to ischemic brain injury with weakness, paresis/paralysis, speech abnormalities, etc which last from anywhere between a day to 21 days followed by either a complete recovery or residual deficits. Loeb et al [1] described the following clinical presentation in RIND:
The clinical features may completely dissipate if thrombolysis is performed soon after the formation of the thrombus [1].
RIND indicates a tiny brain stroke with recovery within a few weeks and should be differentiated from a transient ischemic attack (TIA), which is associated with a reversal of symptoms within twenty-four hours. Currently, the term "RIND" is not used commonly [2] as the diagnosis is based on tissue appearance on imaging studies rather than on the duration of the symptoms.
The diagnosis of RIND is based on a thorough history, physical, neuropsychiatric, and cognitive evaluation along with laboratory and imaging studies. History should elicit the onset, duration, and progress of the neurological deficits as well as a history of co-morbid factors like hypertension, diabetes, etc.
Laboratory tests include complete blood count, blood sugar levels, lipid profile and other tests indicated by clinical presentation. An electrocardiogram may show evidence of cardiac conduction anomalies and while echocardiography may reveal the source of the thrombus and cardiac function. Doppler testing of the internal carotid arteries is important to diagnose carotid artery stenosis as strokes can be associated with up to 70% stenosis.
Currently, the features of the brain tissue on imaging studies like high-resolution computed tomography (HRCT) and diffusion-weighted magnetic resonance imaging (MRI) rather than the time (duration) of deficits is used to detect the condition [2]. CT scans can demonstrate hemorrhage while MRI can detect even tiny infarctions. Several reports indicate that there are very few differences between TIAs and RIND on imaging studies [3] with extracranial abnormalities appearing identical in patients with TIAs, RIND and minor strokes [4] [5]. This suggests that the three types of strokes differ quantitatively but not qualitatively and are therefore regarded as a continuation of the same pathological process [6] [7]. The infarcts are usually of the lacunar type in all three groups with RIND patients having small deep infarcts [8]. Arteriography may help to identify the occlusive thrombus in these patients.