CNS Imaging Features of Antiphospholipid Antibody Syndrome
MRI brain is the imaging modality of choice for APLA, revealing multiple infarcts (territorial, lacunar, and border zone), white matter hyperintensities, and less commonly microhemorrhages, with lesions typically distributed asymmetrically in subcortical and cortical regions. 1, 2
Primary Imaging Findings on MRI
Ischemic Lesions
The hallmark imaging features include:
- Multiple infarcts in various vascular territories - most commonly territorial infarcts in middle cerebral artery distribution, lacunar infarcts, and border zone (watershed) infarcts 1, 2, 3
- Asymmetric distribution affecting both subcortical and cortical areas 2
- White matter hyperintensities on T2-weighted and FLAIR sequences, appearing as nonspecific multiple foci predominantly in deep white matter, frontoparietal, and periventricular regions 3
Additional MRI Characteristics
- Focal hemorrhages may occur, though less common than ischemic changes 3
- Cortical atrophy can develop, particularly in frontoparietal regions 3
- Dural sinus thrombosis in cases of cerebral venous involvement 3
- Demyelination lesions distributed in subcortical and cortical areas 2
Vascular Imaging Findings
Cerebral angiography and transcranial Doppler reveal important vascular abnormalities:
- Intracranial arterial stenosis correlates strongly with territorial infarction (40% vs 7.5% without stenosis, P=0.02), lacunar infarcts (40% vs 11.3%), and border zone infarcts (20% vs 1.9%, P=0.034) 1
- Large cerebral artery occlusion may be present 3
- Many patients show normal angiographic findings despite parenchymal lesions 3
Functional Imaging Patterns
Brain SPECT with SPM analysis demonstrates:
- Consistent cerebral hypoperfusion in bilateral frontoparietal cortices, even in patients without clinical neurological manifestations or structural MRI abnormalities 4
- Marked hypoperfusion in frontal and parietal lobes with heterogeneity both within and between patients 5
This functional impairment suggests chronic microvascular dysfunction mediated by endothelial injury and neuroinflammation, occurring before structural damage becomes apparent 4.
Pathological Correlation
Biopsy findings confirm the vascular nature:
- Small vessel occlusion with inflammatory cell infiltration on skin biopsy 2
- Erythrocyte accumulation with neuronal degeneration and focal demyelination on brain biopsy 2
- These findings establish APLA as an ischemic cerebrovascular disease caused by vascular stenosis or occlusion 2
Clinical Context and Diagnostic Approach
The imaging findings must be interpreted alongside clinical presentation. Headache and thromboembolic events are significantly more common in neurological APLA compared to purely rheumatologic presentations 2.
Key Imaging Protocol Recommendations
For suspected APLA, obtain:
- MRI brain without contrast including DWI, T2 FLAIR, and T2* GRE or SWI sequences 6
- MR angiography to evaluate intracranial vasculature, as stenosis predicts higher infarct burden 1
- Consider functional imaging (SPECT) when cognitive symptoms exist without structural correlates 4
Important Caveats
CT imaging is inadequate for detecting the subtle white matter changes and small vessel disease characteristic of APLA 5. While CT may show white matter hypodensities in frontoparietal and periventricular areas, it misses the majority of clinically relevant findings 3.
The imaging findings are nonspecific but should raise suspicion for APLA in young or middle-aged adults presenting with these patterns in the absence of traditional stroke risk factors (hypertension, diabetes, hyperlipidemia, smoking) 3. The diagnosis requires correlation with persistently elevated antiphospholipid antibodies 2.
Secondary APLA (associated with SLE) shows higher frequency of lacunar infarction compared to primary APLA (P=0.022) 1, though overall imaging patterns remain similar between primary and secondary forms.