BRAIN ARTERIOVENOUS MALFORMATIONS (AVM) AND DURAL ARTERIOVENOUS FISTULAS (DAVF)

DR PREM PILLAY, SENIOR NEUROSURGEON, AVM AND DAVF EXPERT, SINGAPORE

Brain Arteriovenous Malformations (AVMs) and Dural Arteriovenous Fistulas (DAVFs) are potentially serious cerebrovascular conditions that can have significant bleeding causing brain damage (strokes) that can result in weakness, numbness, loss of senses, speech problems (aphasia, dysphasia), paralysis, coma and death. This summary will provide an overview of these conditions, including their presentation, diagnosis, treatments, and less invasive treatment methods.

Brain Arteriovenous Malformations (AVMs)

Presentation

Brain AVMs are abnormal connections between arteries and veins in the brain, bypassing the normal capillary bed. They account for 10-15% of all intracranial vascular malformations[1]. AVMs can present with various symptoms, including:

– Sudden, severe headaches

– Seizures

– Neurological deficits (e.g., weakness, numbness, vision problems)

– Cognitive changes (forgetfulness and memory problems, loss of focus, difficulty with complex tasks or executive function)

However, many AVMs are asymptomatic and are discovered incidentally during brain imaging for other reasons[4].

Diagnosis

The diagnosis of brain AVMs typically involves several imaging techniques:

Computed Tomography (CT): Often the initial imaging modality, especially in emergency situations[1] as they can show the location of bleeding.
Magnetic Resonance Imaging (MRI): Provides detailed images of brain tissue and can show subtle changes related to AVMs[1].
CT Angiography (CTA) and MR Angiography (MRA): These techniques can provide additional vascular details and are often used in conjunction with other imaging modalities[4]. They are less invasive than formal Cerebral catheter Angiography.
Cerebral Angiography: Considered the gold standard for AVM diagnosis. It provides detailed information about the location, size, and vascular architecture of the AVM[1].

Treatment

The treatment of brain AVMs aims to reduce the risk of hemorrhage and alleviate symptoms. Treatment options include:

Surgical Resection: Involves removing the AVM through open brain surgery. This is often the preferred treatment for accessible AVMs[1]. Smaller openings and Advanced Microscopes using florescence together with brain mapping and tractography / connectomes identification can allow safer and more accurate surgery.
Endovascular Embolization: A minimally invasive procedure where embolic agents such as Onyx, PHIL and others are injected through a catheter to block blood flow to the AVM[6].
Stereotactic Radiosurgery: A no Surgery Non-Invasive technology; Uses focused radiation to gradually close off the abnormal blood vessels over time[4].The latest systems use Robotics and Micro (MLC) Radiosurgery for higher accuracy and safety. These can often be done as Day Procedures.
Conservative Management: For some low-risk AVMs, observation and medical management of symptoms may be appropriate[7].

Dural Arteriovenous Fistulas (DAVFs)

Presentation

DAVFs are abnormal connections between arteries and veins within the dura mater, the protective covering of the brain and spinal cord[8]. Symptoms can vary depending on the location and severity of the DAVF:

– Pulsatile tinnitus (rhythmic sound in the ear)

– Headaches

– Visual disturbances

– Neurological deficits

– In severe cases, intracranial hemorrhage or seizures[8]

Diagnosis

The diagnosis of DAVFs involves similar imaging techniques to those used for AVMs:

MRI and MRA: Can detect abnormal blood flow patterns and enlarged blood vessels[5].
CT and CTA: Useful for identifying bony involvement and vascular anatomy[5].
Cerebral Angiography: The definitive diagnostic tool, providing detailed information about the fistula’s location, feeding arteries, and draining veins[5][9].

Treatment

Treatment of DAVFs depends on their classification (e.g., Borden or Cognard systems) and associated risks. Options include:

Endovascular Embolization: Often the first-line treatment, involving the injection of embolic agents to occlude the fistula[9].
Microsurgery: Used when endovascular treatment is not feasible or unsuccessful[10].
Stereotactic Radiosurgery: Can be effective for certain types of DAVFs, especially those in challenging locations[3].
Conservative Management: For low-risk DAVFs, observation and symptom management may be appropriate[8].

Less Invasive Treatment Methods

Recent advancements have led to the development of less invasive treatment options for both AVMs and DAVFs:

Endovascular Techniques

Liquid Embolic Agents: Modern agents like Onyx, PHIL (Precipitating Hydrophobic Injectable Liquid), and Squid offer improved control and effectiveness in embolization procedures[9].
Detachable Coils: Used in combination with liquid embolic agents for more complex cases[9].
Flow Diverters: In special scenarios, devices like the Pipeline Embolization Device can be used to treat certain types of fistulas[9].

Stereotactic Radiosurgery (SRS)

SRS has emerged as an effective and safe alternative to conventional surgery for some AVMs and DAVFs[3]. It offers several advantages:

– Non-invasive procedure

– Lower risk of complications compared to open surgery

– Effective for deep-seated or surgically inaccessible lesions

– Can be used in combination with other treatment modalities

Multimodal Approach

For complex cases, a combination of treatment methods may be employed. For example, endovascular embolization may be used to reduce the size of an AVM before surgical resection or radiosurgery[6].

Conclusion

Brain AVMs and DAVFs are complex cerebrovascular conditions that require careful evaluation and individualized treatment planning explains Dr Prem Pillay, an AVM/DAVF expert. While traditional surgical approaches remain important, less invasive techniques such as advanced endovascular procedures and stereotactic radiosurgery have expanded the treatment options available to patients. These newer methods offer the potential for reduced procedural risks and improved outcomes in selected cases.

As research continues, ongoing advances in imaging technology, embolization techniques, and radiosurgery are likely to further refine and improve the management of these challenging vascular lesions. The choice of treatment should be based on factors such as the patient’s age, overall health, lesion characteristics, and the expertise of the treating team.

If you or your loved ones have an AVM/DAVF, you are most welcome to contact us for an opinion or guidance from our Expert and his team. We are able to design a personalized treatment that has the highest potential success rate and lowest risk rate based on the latest medical evidence and years of experience.