Easing out Stroke Therapy
Neuro intervention procedures allow the treatment of many conditions which previously were considered either surgically difficult to treat or even untreatable
Dr Shaji P Marar
Interventional Neuroradiology (IN) is a minimally-invasive modality of treating a wide spectrum of vascular diseases of the central nervous system. Many vascular diseases of the head, brain, neck and spinal cord like aneurysms, vascular malformations, tumours and occlusive diseases of the arterial and venous systems causing stroke, which required open surgery in the past could now be treated using neuro intervention techniques. Neuro intervention procedures also allow the treatment of many conditions which previously were considered either surgically difficult to treat or even untreatable. It has made emergency stroke therapy possible, so that we can now treat acute strokes if the patient reaches the intervention suite within a defined time frame after the onset of the symptoms.
Spectrum of IN
Beyond diagnostic neuro angiography, IN essentially involves either embolisation or re-vascularisation. Diagnostic neuro angiography is a procedure to diagnose abnormalities of blood vessels of the brain and spinal cord. Small catheters are introduced through a sheath in the femoral artery in the groin under local anaesthesia selectively into the arteries supplying the brain and spinal cord and the blood vessels are then opacified using a contrast medium. A digital subtraction angiography (DSA) unit is essential for performing the angiograms and neuro intervention procedures. DSA remains the gold standard of investigation for vascular diseases of the brain and spinal cord.
Embolisation is a procedure used to occlude an abnormal blood vessel or vascular tissue by substances such as coil, particles or liquid agents like glue delivered through interventional techniques. Revascularisation involves opening up narrowed or occluded blood vessels by angioplasty or clot lysis and restoring normal blood flow in the central nervous system.
Some of the commonly performed neuro intervention procedures include coil embolisation of intra cranial aneurysms, embolisation of cerebral and spinal arterio venous malformations and fistulae, tumour embolisations, revascularisation procedures like carotid, vertebral and intra cranial angioplasties and stentings and emergency stroke treatment like intra arterial and venous thrombolysis.
How are these Procedures Performed?
These procedures are performed through small (1.5-2.5mm) punctures in the femoral artery in the groin. A guide catheter is placed in to the neck artery through the femoral artery. After performing an angiogram, a small micro catheter (less than 0.5 to 1-mm diameter) is navigated into the target area over a micro wire. Embolisation is done using new age precision embolic agents like platinum micro coils or bio glues delivered through the micro catheter to block the abnormal vessels while preserving the normal circulation. Stenosed or occluded blood vessels are opened by angioplasty techniques and super selective clot lysis.
Intra Cranial Aneurysm Treatment
An aneurysm is an abnormal bulge in wall of an artery. It can rupture due to lack of strength in the arterial wall causing intra cranial haemorrhage or when large, can cause a pressure effect on the adjacent brain matter and/or the neighbouring cranial nerves. Aneurysmal rupture has high mortality and morbidity if left untreated. Conventionally these aneurysms required major open neurosurgical treatment involving long hospitalisation. Endovascular coiling has evolved into a viable and less invasive alternative over the last decade. Extremely thin biocompatible platinum coils are deployed in the aneurysm through a micro catheter placed in the aneurysm lumen. The aneurysm is thus occluded and excluded from the normal circulation, thereby preventing a future rupture. When the aneurysm neck is wide, a small balloon or a stent can be used to hold the coils in place within the aneurysm and prevent them from falling back into the normal artery. Patients with unruptured aneurysms usually need two-three days hospitalisation whereas those with ruptured aneurysms and intra cranial bleeding require one-two weeks of hospital stay.
AVM and AVF
Arterio venous malformations (AVM) are abnormal communications between the arteries (which supply oxygenated blood) and veins (which drain impure blood back to the heart) with an intervening abnormal vascular tissue called the nidus. In an arterio venous fistula (AVF), the nidus is absent with a direct communication between artery and vein. AVMs may rupture causing bleeding in the brain or spine resulting in paralysis, loss of vision and speech impairment, depending on the area of the nervous system, which is involved. The treatment of AVM includes surgery, radiotherapy and endo vascular embolisation. Embolisation is used to block the abnormal vascular tissue either completely or reduce its size prior to surgery or radiotherapy. Through fine micro catheters placed in the feeding artery close to the nidus, liquid embolic agents like N-butyl cyanoacrylate (NBCA) or Onyx are injected into the nidus to block it. In arterio venous fistulae and carotid-cavernous fistulae, either arterial embolisation or venous embolisation using coils and glue may be performed.
Acute Stroke Treatment
Acute stroke treatment aims at restoring the blood flow to the brain and reverting neurological function to normal or near normal levels when the patient reaches the DSA suite within a defined time frame after the onset of symptoms of a stroke. In case of strokes involving the carotid circulation a three-six hour time interval is the limit whereas strokes of the vertebral artery circulation can be treated up to 24 hours after onset of the attack and even later. The procedure is performed by super selective cannulation of the occluded artery using a micro catheter and dissolving the clot by fibrinolytic agents such as urokinase or tissue plasminogen activator.
Other Neuro Interventions
Vertebroplasty is a minimally invasive-treatment of painful compression fractures of the spine that may be due to osteoporosis or primary and secondary tumours. The procedure involves the introduction of a needle into the vertebral body through the pedicle and injection of poly methyl methacrylate (PMMA) bone cement. Large hyper vascular tumours may be embolised using percutaneous needle puncture method when vascular access is difficult or impossible. Arterial embolisations may be helpful in controlling cranio facial bleeding due to trauma or tumours.
(The writer is Consultant Interventional Neuroradiologist at Jaslok Hospital and Research Centre, Mumbai)