Dural Sinus Malformation

### Dural Sinus Malformation (DSM): Overview Dural Sinus Malformation (DSM) is a rare congenital cerebrovascular anomaly that affects the dural venous sinuses, usually involving the torcular herophili (confluence of sinuses) and adjacent venous structures. DSMs are characterized by abnormal arteriovenous connections, which can lead to venous hypertension, hydrocephalus, and in severe cases, life-threatening complications.

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## 1. Classification of Dural Sinus Malformations (DSMs) DSMs can be divided into two main types, based on their vascular characteristics:

### A. Low-Flow DSMs (“Aplasia/Hypoplasia of Sinuses”) - These are developmental anomalies where parts of the dural sinuses fail to develop properly. - They usually cause progressive venous hypertension, leading to hydrocephalus. - Typically, no direct arteriovenous shunting is present.

### B. High-Flow DSMs (“Arteriovenous Fistulous Type”) - These malformations involve direct high-flow arteriovenous shunts, where arteries feed directly into the dural venous sinuses. - They are often associated with arteriovenous fistulas (AVFs), leading to rapid venous congestion and risk of hemorrhage. - High-output cardiac failure can develop in neonates due to excessive blood shunting.

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## 2. Clinical Presentation of DSMs ### A. Neonatal Period (Congenital Forms) - High-output heart failure due to excessive arteriovenous shunting. - Severe hydrocephalus due to venous hypertension. - Increased head circumference (macrocephaly). - Seizures or irritability. - Developmental delay in severe cases.

### B. Childhood & Later Presentations - Headaches and increased intracranial pressure. - Hydrocephalus (progressive or intermittent). - Cognitive and motor impairment. - Seizures. - Tinnitus or bruits (due to turbulent blood flow).

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## 3. Imaging & Diagnosis ### A. Ultrasound (Neonatal) - Doppler ultrasound can identify abnormal blood flow and venous congestion.

### B. MRI/MRA (Magnetic Resonance Imaging & Angiography) - Gold standard for evaluating the size, extent, and venous drainage of the DSM. - Can show enlarged dural sinuses, abnormal arteriovenous connections, and associated hydrocephalus.

### C. Digital Subtraction Angiography (DSA) - Definitive diagnostic tool. - Identifies feeding arteries, venous drainage patterns, and the presence of high-flow fistulas.

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## 4. Treatment Approaches ### A. Conservative Management (for Low-Flow DSMs) - In mild cases, observation and medical management of symptoms may be sufficient. - Monitoring for progressive hydrocephalus or venous hypertension.

### B. Endovascular Embolization (Primary Treatment for High-Flow DSMs) - Goal: Block abnormal arteriovenous connections and reduce venous hypertension. - Materials Used:

  1. Liquid embolic agents (e.g., Onyx, NBCA).
  2. Coils (for selective occlusion).
  3. Pressure Cooker Technique (PCT): A specialized embolization method to ensure deep penetration and reduce reflux.

### C. Neurosurgical Options - Ventriculoperitoneal (VP) shunt for hydrocephalus. - Surgical ligation of feeding arteries (rare, usually reserved for non-embolizable cases).

### D. Multistage Approach - Some cases require multiple embolization procedures over time to reduce fistulous connections gradually. - Redo embolization may be needed if significant residual shunting persists.

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## 5. Prognosis - Mild DSMs (Low-Flow): Favorable outcome with conservative management. - High-Flow DSMs with Arteriovenous Shunting:

  1. If left untreated, can lead to neurological deterioration, cardiac failure, and intracranial hemorrhage.
  2. Early and aggressive embolization improves prognosis and prevents long-term disability.

- Mortality & Morbidity:

  1. Neonates with severe AV shunting have a higher risk of mortality due to heart failure.
  2. Neurodevelopmental delay can occur if venous hypertension is prolonged.

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## 6. Summary - Dural Sinus Malformations (DSMs) are rare vascular anomalies of the dural venous sinuses. - High-flow DSMs involve arteriovenous fistulas (AVFs), leading to venous hypertension and potential hydrocephalus. - Diagnosis relies on imaging (MRI/MRA & DSA) to identify abnormal blood flow. - Endovascular embolization (e.g., Pressure Cooker Technique) is the mainstay of treatment. - Early intervention improves outcomes, reducing the risk of neurological complications and heart failure.

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