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