PMC10044343_01
PMC10044343_02
Pre-operative (first surgery). Sagittal, coronal, and axial MRI: (A) T1W + Gad; (B) T2W; sagittal only: (C) TW1 and axial only: (D) SWI. Showing partly hyperacute hematoma (black star) of T1W isointense and T2W hyperintense signal. Early subacute hematoma portion (white star) of T1W hyperintense and T2W hypointense signal. Associated: Two CCMs (target/culprit:blue arrow; incidental contralateral cerebellar peduncle:green arrow) seen as blooming artifacts on SWI, popcorn appearance of mixed signal intensity on T2W, outline against the medial aspect of hematoma cavity on T1W-DVA with a retrospectively determined smaller caliber of its main draining vein (white arrow) seen on T1W + Gad filling, serpiginous flow void on T2W and SWI. Draining via multiple collector veins on T1W+ (blue arrowheads) into caput medusae appearance of transcerebellar veins on SWI (black arrowhead). Prominent channels can be seen connecting both CCMs likely due to high pressures (white arrowheads on SWI).
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F1
MRI brain (Figures 1A-D) showed a cystic lesion in the pons extending to the right middle cerebellar peduncle; a hyperintense portion on T2-weighted imaging (T2W) with the corresponding isointense signal on T1; and T2 hypointense T1 hyperintense part. The DVA was visible in the late arterial and the venous phase on DSA with no other vascular malformations identified (Supplementary Figure 1).
Timeline of clinical course.
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F2
Supplementary Figure 2 is an illustration of the location of the CCM and DVA in the brainstem. A timeline of the clinical episode is presented in Figure 2.
PMC10044343_03
Rebleed after the first surgery. Sagittal, coronal, and axial MRI: (A) T1W + Gad; (B) T2W; axial only: (C) TW1 and (D) SWI. Showing late-stage subacute hematoma or extracellular meth-Hb (black star) with uniform hyperintense T1W signal and iso-hyperintense T2W signal. Target CCM (blue arrow) and untreated contralateral CCM (green arrow) seen as mixed signal intensity on T2W and blooming artifacts on SWI remain. Uniform filling of the main DVA draining vein but slightly stretched over hematoma as it drains into collecting vein on T1W+ (white arrow) and SWI (white arrow). Evidence of elevated pressure in the DVA system from the recurrence of prominent connecting channels (white arrowheads) on T1W+ and SWI.
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F3
Figure 3). Further surgery to resect the target cavernoma was scheduled after 1 month. MRI confirmed further hemorrhage in the surgical cavity, and the DVA continued to fill on gadolinium-enhanced T1W MRI, appearing stretched over the cavernoma with the reappearance of the prominent connecting channels (Figure 3).
Delayed venous congestion and hemorrhage after the second surgery. Sagittal, coronal, and axial MRI: (A) T1W + Gad; (B) T2W; axial only: (C) TW1 and (D) SWI. Marked edema extending from the pons, middle cerebellar peduncles to the cerebral peduncles and subthalamus (orange arrow) on T2W. Reduction in size of the surgical cavity with a small volume acute hematoma (black star) seen as T1W hyperintense and T2W hypointense signal, and early subacute hematoma (white star) with T1W+ isointense and T2W hyperintense signal. The target CCM (blue arrow) appears to have been resected with no blooming artifact at this location seen on SWI. The contralateral CCM remains (green arrow) on SWI. Reduced filling caliber of main DVA draining vein on T1W+ (white arrow) with outline present but no hypointense signal on SWI. Difficult to comment on the pressure of the DVA system in the presence of marked edema.
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F4
T2W changes in the pons, middle cerebellar peduncle, and cerebral peduncle in keeping with venous infarction or congestion. This was associated with a small-volume acute/subacute hemorrhage in the surgical cavity and parenchyma, with a reduction in the caliber of the DVA and its collector vein on TW1+ (Figure 4).
PMC10044343_04
Improvement at 6 months. Sagittal, coronal, and axial MRI: (A) T1W + Gad; (B) T2W axial only: (C) T1W; and (D) SWI. Signal characteristics consistent with late-stage subacute hematoma or extracellular meth-Hb are seen as persisting T1W and T2W hyperintense signals (black star) in the surgical cavity. The additional appearance of a thick hemosiderin ring with hypointense T1, hypointense T2 signal (red star), and clear evidence of thrombus (T1W hyperintensity with reduced filling on T1W + gad) within the DVA system on the right (red arrowhead). The target CCM is confirmed as no longer present on T2* and SWI. The contralateral CCM (green arrow) remains.
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F5
A further MRI, performed 6 months following the last surgery, confirmed no residual targeted CCM, thrombosis within the DVA draining vein, and persistence of the contralateral untreated CCM associated with an increase in prominence of its related anomalous veins (Figure 5).
PMC10044343_05
Delayed venous congestion and hemorrhage after the second surgery. Sagittal, coronal, and axial MRI: (A) T1W + Gad; (B) T2W; axial only: (C) TW1 and (D) SWI. Marked edema extending from the pons, middle cerebellar peduncles to the cerebral peduncles and subthalamus (orange arrow) on T2W. Reduction in size of the surgical cavity with a small volume acute hematoma (black star) seen as T1W hyperintense and T2W hypointense signal, and early subacute hematoma (white star) with T1W+ isointense and T2W hyperintense signal. The target CCM (blue arrow) appears to have been resected with no blooming artifact at this location seen on SWI. The contralateral CCM remains (green arrow) on SWI. Reduced filling caliber of main DVA draining vein on T1W+ (white arrow) with outline present but no hypointense signal on SWI. Difficult to comment on the pressure of the DVA system in the presence of marked edema.
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F4
T2W changes in the pons, middle cerebellar peduncle, and cerebral peduncle in keeping with venous infarction or congestion. This was associated with a small-volume acute/subacute hemorrhage in the surgical cavity and parenchyma, with a reduction in the caliber of the DVA and its collector vein on TW1+ (Figure 4).
PMC10044343_06
Improvement at 6 months. Sagittal, coronal, and axial MRI: (A) T1W + Gad; (B) T2W axial only: (C) T1W; and (D) SWI. Signal characteristics consistent with late-stage subacute hematoma or extracellular meth-Hb are seen as persisting T1W and T2W hyperintense signals (black star) in the surgical cavity. The additional appearance of a thick hemosiderin ring with hypointense T1, hypointense T2 signal (red star), and clear evidence of thrombus (T1W hyperintensity with reduced filling on T1W + gad) within the DVA system on the right (red arrowhead). The target CCM is confirmed as no longer present on T2* and SWI. The contralateral CCM (green arrow) remains.
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F5
A further MRI, performed 6 months following the last surgery, confirmed no residual targeted CCM, thrombosis within the DVA draining vein, and persistence of the contralateral untreated CCM associated with an increase in prominence of its related anomalous veins (Figure 5).