A Case Series of Four Patients with Artery of Percheron Occlusion over a Three-Month Period

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

The Pecheron artery occlusion is a rare cause of stroke and the correct and prompt diagnosis is challenging. This paper describe the different presentations matter of this rare syndrome in the emergency room.

I have some suggestions for the authors to improve the paper sound:

- add a figure that represent the anatomical features of the AOP occlusion variants

- add the MRI images in DWI and FLAIR sequences of the 4 cases described.

- add the angio-MRI images that show the AOP occlusion (almost in one patient)

- please highlight the low usefulness and low specificity of the TC perfusion software in the diagnosis of the posterior circulation stroke. The authors might mention the new software rapid for posterior circulation stroke.

- please explain why in the described patients the MRI was not carried out on time and why the TC angiography was not performed.

 

Author Response

1. Add a figure that represent the anatomical features of the AOP occlusion variants

As requested, we have added a figure on page 5 that represent the anatomical features of the  paramedian thalamic arterial supply according to the Percheron classification as:

Figure 2. Schematic depiction of the thalamus and its arterial supply according to the Percheron classification [11] and the estimated population prevalence of each variant [3]. PCA – posterior cerebral artery, BA – basilar artery. Created with BioRender.com

 

2. Add the MRI images in DWI and FLAIR sequences of the 4 cases described.

Unfortunately, MRI scan was done only in case 3 and case 4. As requested, we added the MRI images in DWI and FLAIR sequences of the case 3 and case 4, please see updated Figure 1. In addition, we added white arrows to highlight the shown changes.

 

3. Add the angio-MRI images that show the AOP occlusion (almost in one patient)

Unfortunately, angio-MRI was not done in any of our described patients. All patients had a CT-angiography, but we cannot visualize the AOP occlusion with CTA.

 

4. Please highlight the low usefulness and low specificity of the TC perfusion software in the diagnosis of the posterior circulation stroke. The authors might mention the new software rapid for posterior circulation stroke.

Thank you very much for your remark. We further highlighted the limitations of CT perfusion. As suggested, we also mentioned the new semi-quantification software, such as RAPID or others, that might improve diagnostic accuracy in posterior circulation stroke, as stated on (page 6, lines 181–185):

“Furthermore, the diagnostic accuracy of CTp is further reduced in posterior circulation stroke (Katyal et al European Journal of Neurology). Even though several automated semi-quantification tools, such as RAPID (iSchemaView), VIZ CTP (Viz.ai), e-Mismatch (Brainomix) or syngo.via (Siemens) have the potential to improve diagnostic accuracy, they are still dependent on the position of the window.”

 

5. Please explain why in the described patients the MRI was not carried out on time and why the CT angiography was not performed.

Thank you very much for your remark. The MRI was not carried out in cases 1 and 2. This was due to the fact that the MRI is less accessible than CT imaging at our department. In case 1, CTp revealed the final diagnosis and an MRI was not necessary. In case 2 the initial CT already showed the infarction of the thalamus.

CT angiography was performed in all four cases. We added the missing descriptions:

CT angiography (CTA) was unremarkable (page 2, line 57-58).

CTA was unremarkable (page 3, line 109).

Reviewer 2 Report

Comments and Suggestions for Authors

A very interesting and informative study. Moreover, very important observations and comments for resident doctors and for doctors already practicing independently. I have a question whether the family interview did not contribute anything or did not suggest anything towards the diagnosis? Could risk factors possibly related to vascular development disorders or any genetic changes influence the diagnosis? Finally, I propose to slightly change the title to: A case series of four patients with artery of Percheron occlusion over a three-month period.

Author Response

1. I have a question whether the family interview did not contribute anything or did not suggest anything towards the diagnosis?

Thank you for your remark. The family interview or heteroanamnesis was obtained in all four cases. This did not reveal any additional information that would help us in making the final diagnosis.

2. Could risk factors possibly related to vascular development disorders or any genetic changes influence the diagnosis?

Artery of Percheron is an anatomical variant of the paramedian thalamic arterial supply, present in about 10% of the population. To the best of our knowledge there are no studies on the exact etiological origin of this variant. It would be interesting to know if the appearance of this variant has a genetic cause.

3. I propose to slightly change the title to: A case series of four patients with artery of Percheron occlusion over a three-month period.

We agree with the proposed change and as requested, we changed the title into: “A case series of four patients with artery of Percheron occlusion over a three-month period”.

 

Reviewer 3 Report

Comments and Suggestions for Authors

This is a nice review which calls attention to this acute infarction distribution pattern being a potential explanation for a patient presenting with altered mental status. I view this as important in light of the potential for significant benefit with the use of thrombolytic therapy if the clinical presentation is properly recognized in a timely fashion. 

Author Response

We thank the reviewer for comments.