Role of Neuro Intervention

The role of neuro intervention is to treat diseases of the brain's blood vessels from inside the vessels themselves. Working through catheters and wires introduced at the groin or wrist, a neurointerventionist can remove a clot that is causing a stroke, seal a bleeding aneurysm or block an abnormal tangle of vessels, reaching deep parts of the brain that a surgeon's scalpel or a neurologist's drugs cannot reach.

Dr. Tariq Matin, Director & Chief, Neurointerventional Surgery, Artemis Hospitals, Gurugram, India, describes the specialty in exactly those terms: catheters reach where the knife and the medicine cannot, and do the job there. This guide sets out what the specialty is, how it developed, which conditions it treats, when a patient should be referred, and which patients can safely travel for treatment. Two companion articles go deeper: one on ischaemic stroke treatment, time windows and mechanical thrombectomy, and one on brain aneurysm treatment, from coiling and clipping to AVM embolisation.

What neurointervention is, and who practises it

Neurointervention is the catheter-based treatment of neurovascular disease: disorders of the arteries and veins that supply and drain the brain, spinal cord, head and neck. The same specialty goes by several names. It can be called interventional neurology, endovascular neurosurgery or interventional neuroradiology, depending on the training route of the person practising it.

Dr. Matin regards that diversity as a strength. A radiologist by background, he began his training in the field in 2005 and has practised it for more than 20 years. His own route ran through a residency in neuroradiology at the All India Institute of Medical Sciences and a fellowship under Professor Georges Rodesch in Suresnes, near Paris, with a further certification from the University of Toronto. His team deliberately draws on neurology, neurosurgery and radiology, and trains doctors from all three. The centre trains specialists from India and abroad, and its members have proctored teams in other countries as they set up their own programmes.

When he began training, the specialty was, in his account, in its infancy in Europe and almost unknown in large parts of the world, including much of India. Today, in Dr. Matin's assessment, it can produce a paradigm shift in the treatment of neurovascular disease.

What a neurointervention unit needs: the man, the machine and the tools

Dr. Matin reduces a neurointervention service to three elements: the people, the machine and the tools. All three must be present, around the clock.

• The people. His team brings together specialists from neurosurgery, neurology and radiology, supported by catheterisation laboratory technicians and nursing staff. It runs 24 hours a day, seven days a week, 365 days a year, because a stroke does not wait for office hours. Besides Dr. Matin, four other doctors on his team perform these procedures, and the unit runs a fellowship programme.
• The machine. The procedures take place in a biplane catheterisation laboratory, a dedicated neuro angiography suite with two imaging planes that view the brain's vessels from two angles at once. The same machine produces three-dimensional angiograms, CT angiograms and CT images on the table.
• The tools. Catheters, microcatheters, wires, coils, stents, balloons, clot retrieval devices and embolic agents are stocked in the laboratory itself.

How digital subtraction angiography works

The core imaging technique is digital subtraction angiography (DSA). Contrast dye is injected into an artery, for example the internal carotid artery in the neck, and X-ray images are taken as it flows through the brain. A conventional angiogram shows the skull as well as the vessels. Digital subtraction removes the bone from the image, leaving only the contrast-filled vessels, so even small branches are seen clearly.

From DSA, the team can acquire a rotational three-dimensional angiogram, turn it on screen and study the architecture of a lesion from any angle. Dr. Matin showed a small vascular malformation that had bled: the three-dimensional view and super-selective injections allow the team to understand its angioarchitecture before treating it. The same machine also visualises the devices once they are deployed.

History of neurointervention: from the Seldinger technique to modern stroke care

Dr. Matin frames the history of the specialty with Isaac Newton's line about standing on the shoulders of giants. The milestones he highlighted:

1. 1927: the first cerebral angiogram. The Portuguese neurologist Egas Moniz performed the first cerebral angiography by injecting a radio-opaque substance into the carotid artery. Moniz later received the Nobel Prize, though not for angiography: the 1949 prize recognised his work on prefrontal leucotomy. Early angiograms were obtained through the carotid artery in the neck.
2. 1953: the Seldinger technique. The Swedish radiologist Sven-Ivar Seldinger (1921 to 1998) described a simple method: puncture a vessel with a hollow needle, pass a wire through it, remove the needle and exchange catheters over the wire. It works for any lumen, whether a blood vessel, the gut or an airway. It looks obvious today, but Dr. Matin calls it a revolution for every kind of intervention.
3. 1960s: the femoral route. Access through the femoral artery in the groin replaced the cumbersome direct carotid approach. Today, with better tools, the radial artery at the wrist is also used frequently.
4. 1960: the first embolisation. Alfred Luessenhop and William Spence reported the first therapeutic embolisation (deliberately blocking an abnormal vessel from inside) of a cerebral arteriovenous malformation.
5. The 1970s: balloons. Fedor Serbinenko used balloon catheters to occlude vessels and aneurysms, while the neurosurgeon Charles Drake advanced the surgery of neurovascular disease.
6. Late 1980s: intra-arterial fibrinolysis. Clot-dissolving drugs delivered directly into the blocked artery were already being reported for stroke.
7. The 1990s: detachable coils. Guido Guglielmi in Italy devised platinum coils that detach by an electrolytic mechanism once placed inside an aneurysm. Detachable coils revolutionised aneurysm treatment.
8. The teachers. Pierre Lasjaunias, regarded by Dr. Matin's generation as the father of modern neurointervention, co-authored the multi-volume textbook Surgical Neuroangiography with Alex Berenstein and Karel ter Brugge. Professor Rodesch, under whom Dr. Matin trained, was Lasjaunias's pupil.
9. 2002: evidence. The International Subarachnoid Aneurysm Trial (ISAT), led by Andrew Molyneux of Oxford, randomised 2,143 patients with ruptured aneurysms between surgical clipping and endovascular coiling, and found coiling the better option for those suitable for both.
10. 2015: the landmark year. Trials of mechanical thrombectomy for stroke were so decisive that the American Heart Association and American Stroke Association made the procedure a standard of care with the highest class of recommendation. In Dr. Matin's words, from there there has been no looking back.

Dr. Matin divides the arc into three eras: the 1990s as the era of evolution, the 2000s as the turn to evidence-based medicine, and the period from 2010 onwards as an era of explosion that is still under way.

The role of neuro intervention: which conditions it treats

The specialty deals primarily with stroke, in both its forms. An ischaemic stroke occurs when an artery is blocked; a haemorrhagic stroke occurs when a vessel ruptures. Dr. Matin's scope covers:

• Ischaemic stroke, arterial and venous: mechanical thrombectomy (catheter removal of the clot) for large-vessel occlusion, a blockage of one of the main arteries of the brain; carotid, intracranial and vertebral artery stenting to prevent a second stroke; and recanalisation of the brain's venous sinuses in severe cerebral venous thrombosis.
• Haemorrhagic stroke: coiling of ruptured aneurysms causing subarachnoid haemorrhage, management of vasospasm (spasm of the brain's arteries after a bleed), and embolisation of the lesions behind lobar bleeds, such as arteriovenous malformations.
• Malformations elsewhere: spinal vascular malformations, paediatric vascular malformations, and high-flow and low-flow vascular malformations of the head and neck.
• Tumours and bleeding: tumour embolisation, and control of acute bleeding in the head and neck.

The principle behind all of it is simple, as Dr. Matin put it to the audience: there is either a blockage or a leakage. The interventionist either opens the blockage or seals the leakage. The stroke article covers the first; the aneurysm article covers the second.

Working from the inside: how catheters reach deep vessels

Patients and families often fear any procedure on the brain. Dr. Matin explains the difference with an analogy. Picture a blocked drain under a city. The surgical approach digs up the road from above to reach it. The endovascular approach enters the drainage system where it begins, follows the map to the blockage and clears it, without digging at all. A neurosurgeon must work from the outside in; a neurointerventionist works from the inside, travelling through the vessels with catheters and wires to the deepest structures of the brain. Reaching them, he says, is not as difficult as people imagine.

When to refer a patient to a neurointerventionist

The most common gap, in Dr. Matin's experience, is awareness. The specialty is still unknown in many medical circles, and many doctors do not know what it can do. Because ischaemic stroke forms the largest share of the work, he argues that awareness must extend beyond doctors into the community.

The practical trigger is the FAST acronym:

• Face: sudden drooping of one side of the face.
• Arm: sudden weakness of an arm.
• Speech: sudden disturbance of speech.
• Time: these signs mean a stroke is evolving, and every minute counts.

A stroke in evolution needs an immediate CT scan. Nothing can be diagnosed clinically alone, Dr. Matin stresses, because the same symptoms can come from a haemorrhagic or an ischaemic stroke, and only imaging tells them apart. Sudden loss of a function the patient had before, such as lifting an arm or speaking, points to a stroke, most often an ischaemic one. A sudden, severe headache that the patient describes as the worst of their life, or sudden seizures, also demand neuroimaging with CT or MRI.

His rule for physicians and families alike: whenever a neurological function is suddenly lost, the patient must be rushed to a neuro care centre.

Which patients can travel abroad for treatment

For international patients, Dr. Matin draws a clear line between conditions that cannot wait and conditions that can.

Acute stroke cannot travel. While a stroke is evolving, brain tissue is dying, and treatment must happen within hours: up to 4.5 hours for a clot-dissolving drug and 6 hours for mechanical thrombectomy, extending to 24 hours in selected patients chosen on imaging. Acute stroke care therefore has to be built in and around the patient's own locality; it cannot depend on a few good centres far away. The stroke article explains these windows in detail.

Secondary prevention can travel. Once a stroke has occurred and a vascular cause has been found, such as a narrowed or blocked artery, treating that lesion may prevent the next stroke. These patients can make a calculated decision and be transferred. Intracranial angioplasty, for example, is a genuinely complex procedure that needs a good centre and experienced hands. Most of Dr. Matin's overseas patients with ischaemic stroke come for exactly this kind of revascularisation, and his team recently placed an intracranial stent for a patient from an African country.

Survivors of a ruptured aneurysm can travel, and should not delay. Subarachnoid haemorrhage is often so devastating that many patients are in poor condition on arrival, or brain dead by the time they reach hospital. Those who come from overseas have usually survived the acute phase and stabilised. Their aneurysm, however, remains untreated and can rupture again at any time. Dr. Matin calls it a ticking bomb: second ruptures are usually massive and devastating. These patients are transferred so the aneurysm can be secured. Indicative costs for securing an aneurysm are on the aneurysm clipping and coiling cost page.

Is age a barrier to treatment?

No. Asked how his team helps patients over 70, Dr. Matin answered that his team has treated patients of almost 90 and 100 years of age and seen them recover. Age, in his practice, is not a criterion for refusing treatment.

How safe is neurointervention?

Dr. Matin does not claim the procedures are free of risk. Complications occur, as they do with any treatment, and the standard is that they stay within established operating procedures. Even a paracetamol tablet, taken casually for a fever, can cause complications; no one can call it 100% safe. In the same way, neurointervention and neurosurgery carry risk, but precision and technology have improved so much that complication rates have fallen significantly. The procedures are far less frightening than they were 10 or 20 years ago.

How a treatment decision is made

At Artemis, treatment choices are made by a team rather than an individual. Dr. Matin, the four other interventionists and the fellows review the imaging together on screen, each contributes, and the group agrees a modality. They then discuss the case with the neurosurgical colleagues, with whom Dr. Matin describes a close and harmonious working relationship. Finally, the team meets the patient's family to explain the options, the complexity of each procedure and the costs involved, and the family decides after that informed discussion. Most choose an endovascular procedure.

The full exchange between Dr. Matin and the doctors attending, including questions on referral, carotid stenosis and wide-necked aneurysms, is on the Live Discussion page. Related specialists are listed under neurointervention.