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Draining Vein Shielding During Gamma Knife Radiosurgery in Intracranial Arteriovenous Malformations

Abnormal blood artery tangles in the brain where arteries join veins directly without the typical capillaries in between are known as intracranial arteriovenous malformations (AVMs). High-flow shunts are produced as a result, which may cause seizures, neurological impairments, and brain haemorrhage. A popular non-invasive technique for treating AVMs is Gamma Knife radiosurgery (GKRS), which uses concentrated radiation to gradually destroy the nidus (the aberrant vascular core).

highlighting the risk associated with treating the draining vein.
highlighting the risk associated with treating the draining vein.

Making sure the AVM nidus is adequately treated while safeguarding the draining veins—which are essential to preserving safe blood flow until the AVM is totally destroyed—is one of the main problems during Gamma Knife radiosurgery. Draining vein shielding is the idea that achieves this equilibrium.

Draining Vein Shielding: What is it?

Draining Vein Shielding_ What is it
Draining Vein Shielding_ What is it

The planning technique used in Gamma Knife radiosurgery to reduce or eliminate radiation exposure to the AVM’s draining veins is known as “draining vein shielding.”

Why it’s important

  • An “escape route” for high-pressure arterial blood travelling through the AVM is provided by draining veins.
  • Early radiation damage to these veins raises the likelihood of thrombosis (clotting) or blockage, which can result in abrupt spikes in intranidal pressure and catastrophic bleeding.
  • Consequently, until the nidus is destroyed, the veins must stay open.

The process of shielding is adjusting the radiation dose distribution to target the nidus while exposing the draining veins to little or no radiation.

Draining Veins’ Function in AVMs

Draining Veins' Function in AVMs
Draining Veins’ Function in AVMs
  • High-pressure blood is delivered to the AVM nidus by arterial feeders.
  • There are abnormal connections inside the tangled cluster known as the nidus.
  • This blood leaves the AVM and enters the regular venous system through draining veins.

These veins are carefully identified on angiography and MRI during Gamma Knife planning to guarantee their preservation during treatment.

Draining Vein Shielding in Gamma Knife Radiosurgery: A Method

Draining Vein Shielding in Gamma Knife Radiosurgery
Draining Vein Shielding in Gamma Knife Radiosurgery

Planning and Imaging

  • The AVM architecture is mapped using high-resolution digital subtraction angiography (DSA), MRI, and MRA.
  • During treatment planning, the draining veins are identified and marked independently.

Dosage Forming

  • Several concentrated beams are used by Gamma Knife, and they converge on the nidus.
  • The radiation can be shaped to cover the nidus while excluding the draining veins by varying the radiation dosage fall-off, beam collimation, and isocenter location.

Targeting Specific Areas

  • The Nidus core receives the majority of the radiation.
  • Sharp dose gradients “shield” the draining vein route, preventing exposure levels below those that would harm the endothelium.

Support for Physics and Software

  • Contouring draining veins and automatically optimising plans to protect them are made easier by modern planning tools.
  • To provide safe margins, dose-volume histograms are examined.

The Significance of Draining Vein Shielding

  • Prevents Early Venous Occlusion: Prevents veins from closing too soon, which could cause bleeding.
  • Lowers Radiation Complications: Lowers the chance of necrosis, venous infarction, or edema.
  • Enhances Treatment Safety: Maintains physiological drainage while offering controlled nidus obliteration over two to three years.

Clinical Results and Related Data

  • According to studies, the risk of haemorrhage during radiosurgery is considerably decreased by protecting draining veins.
  • Prioritising nidus coverage while preserving veins results in high AVM obliteration rates.
  • This strategy is especially important for large, complex AVMs or those found in deep, expressive brain regions.

Restrictions & Things to Think About

  • Partial Nidus Coverage: Vein shielding in extremely complicated AVMs can occasionally result in insufficient nidus dosage.
  • Longer Obliteration Time: Compared to more vigorous dosage, maintaining veins may cause the AVM to close more slowly.
  • Tailored Approach: Since every AVM has a different angioarchitecture, shielding techniques need to be adapted.

In conclusion

The foundation of safe and efficient Gamma Knife radiosurgery for cerebral AVMs is draining vein shielding. Neurosurgeons and radiosurgeons can lower the risk of bleeding, avoid serious complications, and enhance long-term therapy results by avoiding excessive radiation exposure to the draining veins.

Draining vein shielding is now a standard but essential component of AVM radiosurgery treatments due to advancements in imaging, treatment planning software, and radiation delivery methods. In the end, it serves as an example of how neurosurgical practice strikes a compromise between aggressive lesion targeting and cautious preservation of important arterial structures.

Sources:

  1. https://www.slideshare.net/slideshow/draining-vein-shielding-in-avm-a-new-technique-in-gamma-knife/43424087
  2. https://www.researchgate.net/publication/271591960_Draining_Vein_Shielding_in_Intracranial_Arteriovenous_Malformations_During_Gamma-Knife_A_New_Way_of_Preventing_Post_Gamma-Knife_Edema_and_Hemorrhage
  3. https://plu.mx/plum/a/?doi=10.1227/neu.0000000000000660&theme=plum-bigben-theme
  4. https://pubmed.ncbi.nlm.nih.gov/25635888/
  5. https://academic.oup.com/neurosurgery/article-abstract/76/5/623/2452075?redirectedFrom=fulltext
Table of Contents

You May Also Know Related to Gamma Knife
FAQ’s

Gamma Knife uses 192–201 precisely focused beams of gamma rays that converge at a single target point in the brain. This high dose of radiation damages the DNA of abnormal cells, stopping their growth or causing them to shrink, while minimizing exposure to nearby healthy tissue.

No, Gamma Knife is not a traditional surgery. It is a non-invasive outpatient procedure performed without any incision, stitches, or general anesthesia in most cases.

Gamma Knife is commonly used for:

Brain tumors (benign and malignant)
Metastatic brain lesions
Arteriovenous malformations (AVMs)
Trigeminal neuralgia
Acoustic neuromas (vestibular schwannomas)
Pituitary tumors
Certain functional disorders (like tremors)

The procedure is generally painless. Patients may feel mild pressure while the head frame (if used) is applied or may experience slight discomfort from anesthesia injections, but the treatment itself is not painful.

Depending on the condition and treatment plan, Gamma Knife may take 30 minutes to 3 hours. Most patients go home the same day.

Common side effects are usually mild and temporary, including:

Headache
Nausea
Fatigue
Mild scalp swelling or tenderness at the frame site
Rarely, some patients may experience delayed radiation effects such as brain swelling or radiation necrosis.

Most patients can return to their normal routine within 24–48 hours after the procedure.
You may feel mild fatigue for a few days.
Follow-up imaging is usually required after 1 year.

Gamma Knife has a high success rate and has been used worldwide for decades. Its effectiveness depends on the condition treated, size and location of the lesion, and overall patient health. In many cases, it offers results comparable to open surgery with fewer risks.

Yes, in some cases Gamma Knife treatment can be repeated if the disease recurs or if new lesions develop.

Yes. Gamma Knife is considered one of the safest and most precise forms of radiosurgery, with millions of patients treated globally and extensive clinical data supporting its use.

Eligibility depends on factors such as:

Size and location of the lesion
Overall health and age
Whether open surgery is too risky
A neurosurgeon and radiation oncologist will decide if Gamma Knife is the best option for you.

A detailed MRI or CT scan is performed to map the brain.
A lightweight head frame or mask is used for accuracy.
Your doctors plan the radiation dose and target areas using specialized software.

Local anesthesia is given if a head frame is used.
General anesthesia is usually not required, except for children or patients unable to remain still.

Costs vary depending on hospital, city, and condition treated. On average, Gamma Knife in India ranges from ₹1.5 lakh to ₹4.5 lakh. It is usually more affordable compared to treatment in Western countries. At AIIMS Delhi, it is much more affordable around ₹75,000 which makes it affordable for the patients in need.

AIIMS Delhi is one of the leading centres for Gamma Knife in India.

AIIMS uses the latest Gamma Knife Perfexion system.

It has successfully treated thousands of patients for brain tumors, blood vessel problems, and even eye cancers.

The treatment is done by expert neurosurgeons such as Dr. Deepak Agrawal and team.

Clinic timings for Gamma Knife OPD at AIIMS Delhi: Monday & Friday, 8:00 AM – 9:00 AM.

Cost is around ₹75,000 and is subsidized compared to private hospitals.

The whole procedure is usually done in one day:

  • Consultation & Planning – Doctors review your scans and decide the treatment.
  • Head Frame/Mask – A lightweight frame or mask is placed to keep your head still.
  • Imaging – MRI/CT scans are done to locate the exact target.
  • Treatment Planning – Specialists plan the dose and direction of radiation.
  • Gamma Knife Treatment – You lie on the machine; painless radiation beams treat the target (30 mins–3 hrs).
  • Recovery & Discharge – The frame is removed, and most patients go home the same day.
  • Follow-up – MRI after a few months to check results.

Before you get a treatment date, you need to complete a few steps:

  • OPD Registration – Visit the Neurosurgery OPD (Gamma Knife clinic at AIIMS, Mon & Fri 8–9 AM) and register.
  • Consultation with Doctor – Meet the neurosurgeon who will check your reports, MRI/CT scans, and medical history.
  • Investigations – Sometimes fresh MRI/CT or blood tests are needed for treatment planning.
  • Medical Fitness – Basic checks like blood pressure, sugar, heart condition, etc.

Financial/Insurance Approval –

  1. If using Ayushman Bharat or government schemes, you need approval papers.
  2. If self-paying, you will be given the estimated cost (~₹75,000 at AIIMS).
  • Consent & Admission Slip – Once doctors confirm you are fit and formalities are done, you sign the consent form.
  • Treatment Date Allotment – A date is given for your Gamma Knife procedure.

Once you receive your Gamma Knife date, you’ll need to do a few simple things before the procedure:

  • Admission Process – Report to AIIMS on the morning of your procedure and complete admission at the Neurosurgery ward/Daycare.
  • Paperwork – Carry your OPD slip, MRI/CT films, blood test reports, admission slip, and ID proof. If you are covered under Ayushman Bharat/insurance, keep those approval papers ready.
  • Consent Forms – You (or a family member) will sign consent for the procedure and anesthesia.
  • Medical Check-up – Doctors will check your BP, sugar, heart rate, and do a quick physical exam.
  • Fasting – Usually, you will be asked to not eat or drink for 6 hours before the procedure.
  • Pre-Procedure Prep – An IV line may be put, and medicines (sedation/antibiotics if needed) are given.
  • Treatment – You are then taken to the Gamma Knife room for frame/mask placement, imaging, and treatment.

After the procedure, you’ll be observed for a few hours and most patients are discharged the same day or next morning.

Urea & creatinine

No, You can have light breakfast.

Yes, you can take the medicine and then come for the treatment.

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