A rare and deceptive venous anomaly, sinus pericranii.

To the Editor,

This letter attempts to highlight concerns to the anesthesiologist when dealing with a case of sinus pericranii and hence that safe perioperative coverage of the same may be provided.

A 21-year-old female patient presented with headache and heaviness over an enlarging frontal bone defect. Within the defect, a soft, compressible, mass lesion was observed, the clinical characteristic being its disappearance when the patient was in sitting position and its appearance when the patient was in recumbent position. A diagnosis of sinus pericranii, a rare venous anomaly was made and patient was scheduled for frontal craniotomy and excision. The preoperative examination was unremarkable, and general anesthesia was planned and executed for the case. After induction, a transcranial Doppler study was carried out. It did not reveal any abnormal flow velocities in the anterior cerebral artery or middle cerebral artery, on comparison of the bone defect window and transtemporal window, respectively. Decongestive therapy using 200 mL of 20% mannitol was administered to ensure a lax dura for the surgeon's comfort. Craniotomy and exposure of the sinus pericranii was done without difficulty [Figure 1]. However, despite meticulous surgical technique, tears in the connecting venous channels (sinus pericranii to the superior sagittal sinus) occurred intraoperatively causing torrential blood loss (2.5 L). Hemorrhage was eventually controlled by the surgeons and patient was successfully resuscitated by the anesthesia team. After overnight elective ventilation, the patient was extubated and on examination found to have no neurological deficits.

Figure 1

Intraoperative image showing dilated venous anomaly on near midline, after craniotomy

Stromeyer coined the term sinus pericranii in 1850.[1] It is a rare condition that is characterized by a large communication between the intracranial and the extracranial venous drainage pathways, in which blood circulate bidirectionally through dilated veins of the skull. It can be congenital, acquired or traumatic in nature. Sinus pericranii may be part of a syndrome in some patients, but can occur as an isolated condition. Associations with craniosynostosis, Crouzon's syndrome, Apert's syndrome and Hunter's syndrome are well documented.[234] Therefore, a careful workup is necessary along with necessary planning for anesthesia. Sinus pericranii is compounded by multiplicity, venous channels connecting to the intracranial venous system, and presence of venous lakes in close association with the abnormality. The latter is associated with significant blood loss intraoperatively.[5] Of further concern to anesthesiologist are the following two: hemorrhage and venous air embolism. The potential for blood loss should not be underestimated without disaster, especially in a case with multiplicity. This did occur in our case; however, we were prepared to handle the situation and were therefore able to salvage the situation. Although venous air embolism is another concern, requiring appropriate anticipation, monitoring and management, if it occurs, however did occur in our case. We conclude by stating that sinus pericranii is a rare venous anomaly, and that the above highlighted issues should be considered by the anesthesiologist whilst in preparation for surgery for such a case.