Pilot Study to Evaluate the CereVasc® EShunt® System in the Treatment of Communicating Hydrocephalus

Inclusion Criteria: * Patient is ≥ 21 years old * Patient or legally authorized representative is able and willing to provide written informed consent * Post-aneurysmal SAH with Hunt and Hess Grades I-IV with EVD in place for at least 7 days with the need for a permanent CSF shunt determined through a failed EVD clamping trial defined as: 1. Post-clamping ICP of \> 20 cmH2O for 15 minutes, or 2. Post-clamping ICP \> 25 cmH2O for \< 15 minutes with patient intolerance to EVD clamping, or 3. Significant radiographic signs of increasing ventriculomegaly, or 4. Neurological decline attributable to ventriculomegaly and requiring CSF diversion * Clinical signs and symptoms of communicating hydrocephalus * Neurologically stable without evidence of severe vasospasm * Pre-procedure MRI confirmation of anatomy suitable for eShunt Procedure, as described in Section 1.8.3.4.2 and confirmed by subject screening committee (SSC) * Pre-procedure CT confirmation of anatomy suitable for eShunt Procedure, as described in Section 1.8.3.4.2 and confirmed by SSC Exclusion Criteria: * Presence of gross blood in CSF * Signs or symptoms of obstructive hydrocephalus * Active systemic infection or infection detected in CSF * Prior or existing shunts, endoscopic third ventriculostomy, or any previous surgical intervention for hydrocephalus * Hypersensitivity or contraindication to heparin or radiographic contrast agents which cannot be adequately pre-medicated, desensitized or where no alternative is available * Occlusion or stenosis of the internal jugular vein * Venous distension in the neck on physical exam * Medical conditions associated with prolonged elevation of jugular venous pressure, including jugular vein stenosis or stricture, right sided heart failure, cirrhosis of the liver, arterial venous fistulas in the arm for dialysis purposes, or an arterial venous fistula or malformation in the neck or brain * Atrial septal defect or patent foramen ovale identified on cardiac echocardiogram * History of bleeding diatheses, coagulopathy or will refuse blood transfusion in cases of emergency * Stroke or transient ischemic attack within 180 days of eShunt Procedure * Presence of a deep vein thrombosis superior to the popliteal vein * International Normalized Ratio (INR) or Partial Thromboplastin Time (PTT) results outside of normal range (INR 0.8-1.4; PTT 25-35 seconds) * Presence of a posterior fossa tumor or mass * Life expectancy \< 1 year * Currently participating in another investigational drug or device trial that could conflict with study data collection or follow-up * Pregnant * Unwilling or unable to comply with follow-up requirements