DISCUSSION
TTP is a hematological emergency which requires prompt therapy to reduce morbidity and mortality. TTP is characterized by deposition of intravascular platelet microthrombi induced by autoantibody-mediated deficiency of ADAMTS13, a von Willebrand factor (VWF)-cleaving protease (8), resulting in thrombocytopenia, microangiopathic hemolytic anaemia (MAHA), renal abnormalities, neurologic disturbances, and fever. The pentad of clinical syndromes which was proposed to constitute the diagnosis of TTP only occurs in 5% of cases. Currently, clinical diagnosis is made when there is the presence of microangiopathic hemolytic anaemia, thrombocytopenia, with or without neurological and renal involvement and without another identifiable cause (9). Our patient presented with stroke, seizures, intracerebral haemorrhage, MAHA, thrombocytopenia, and acute kidney injury. There was no identifiable cause in our patient. TTP may also present with a transient ischemic attack (TIA) or stroke with or without hematological changes (10, 11). In a series of 47 patients with acute TTP, the most common neuroradiologic finding was posterior reversible encephalopathy syndrome (PRES), while large ischemic infarctions and hemorrhage were uncommon (12). Our patient presented with ischemic stroke and later intracerebral haemorrhage occurred. Many patients with TTP present with the triad of thrombocytopenia, microangiopathic hemolysis, and neurological abnormalities. Some of them may also have fever and renal abnormalities. However, it is important to note that neither the triad nor the pentad of presentation can be relied upon for the diagnosis of TTP. In practice, a constellation of thrombocytopenia and microangiopathic hemolysis should always raise the suspicion of TTP. Acute kidney injury requiring dialysis are uncommon (13) but our patient had an acute kidney injury and was hemodialysed whiles undergoing plasma exchange transfusion.
TTP results from either a congenital or acquired decrease/absence of the von Willebrand factor protease ADAMTS13. Low levels of ADAMTS13 result in microthrombi formation which leads to end organ ischemia or damage (14, 15, 16). This is due to inability of the ADAMTS13 to cause an inactivation of the large multimer von Willebrand factor (vWF) that is necessary to prevent spontaneous coagulation. These larger multimers have a high avidity to bind platelets and initiate thrombi formation. However, the availability of ADAMTS13 activity assays are not available in many developing countries (17), making the confirmation of the diagnosis difficult. In attempting to solve this problem, prognostic scores are now being used to reduce the chance of mistakes and increase the clinical diagnosis accuracy. Among these developed scores is the PLASMIC score which has been shown to be practical and effective, according to some validated studies (18, 17). Since our patient couldn’t afford the ADAMTS13 assay, and this assay is not readily available in the country, the PLASMIC score was used as an alternative to confirm our diagnosis of TTP. She had a risk score of 7 which is categorized as a high-risk for TTP and a 96.2% risk of severe ADAMTS13 deficiency (≤10%). (Table 3 and Table 4)
Table 3. PLASMIC Score