Subpial Dissection [Neurosurgery Wiki]

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====== Subpial Dissection ======

===== 🔍 Definition =====
**Subpial dissection** is a [[microsurgical technique]] in which the surgeon operates beneath the pia mater, maintaining it as a protective membrane between the surgical field and the underlying brain cortex. This approach allows lesion removal or exposure of deep structures while minimizing cortical injury and preserving vascular integrity.

===== ⚙️ Surgical Technique =====
  * Identify the **pial surface** under high magnification.
  * Incise the **pia mater sharply** using a microknife or fine bipolar forceps.
  * Continue dissection **beneath the pia**, using gentle suction and blunt dissection tools.
  * The pia is kept **intact over the brain parenchyma**, and the dissection proceeds **between the pia and the lesion or arachnoid**.
  * Achieve meticulous **hemostasis** using bipolar coagulation at the pial edge, avoiding direct cortical coagulation.

===== 🧭 Indications and Applications =====
  * **Tumor surgery**: low-grade gliomas, meningiomas invading the cortex
  * **Vascular lesions**: AVMs, cortical aneurysms
  * **Access to deep structures**:
    * Transsylvian approach
    * Transcortical approach
    * Transplanum–transpolfar approaches (endonasal)
  * **Epilepsy surgery**: selective amygdalohippocampectomy, disconnections

===== 🛡️ Advantages =====
  * Preserves **cortical and vascular integrity**
  * Reduces risk of **neurological deficits**
  * Minimizes **postoperative seizures**
  * Allows **safe retraction and exposure** of eloquent areas

===== ⚠️ Risks and Considerations =====
  * Risk of damaging **subpial vessels** (possible infarcts)
  * Infiltrative or inflammatory lesions may **obscure the subpial plane**
  * Requires **microsurgical precision** and excellent visualization

===== 🧠 Key Anatomical Notes =====
  * The **pia mater** contains pial vessels and marks the outermost layer of the cortex.
  * Subpial dissection preserves **arachnoid and vascular layers** while accessing lesions directly beneath the cortical surface.

===== 📚 References =====
  * Yasargil MG. ''Microneurosurgery''. Volumes I–IV. Thieme.
  * Berger MS, Hadjipanayis CG. Surgical techniques for infiltrating gliomas. ''Surg Neurol''. 2007.
  * Spetzler RF, et al. Use of subpial planes in eloquent cortex surgery. ''Neurosurgery''. 1992.