Vascular Conditions
Arteriovenous malformations (AVMs)
Brain arteriovenous malformations (AVMs) are abnormal connections between the arteries and veins within the brain with associated tangles of vessels. In normal states arteries carry oxygenated blood away from the heart and veins return deoxygenated blood to the heart and lungs. This process is disrupted in AVMs. Most people are born with AVMs, although they may occur rarely later in life. In rare cases they can occur as a result of a genetic condition.
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AVMs can be silent (asymptomatic) and remain undetected until they burst and bleed causing a haemorrhage. This occurs in about half of the AVMs and usually in younger patients under the age of 40. Symptoms of bleeding can be headache, weakness or limb paralysis, vision loss, difficulty speaking, confusion or problems with walking. AVMs can also cause seizures, headaches, or neurological problems like weakness even in cases of no haemorrhage.
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Screening for brain AVMs is performed with CT scans and CT angiography which can demonstrate the AVM and whether a bleed has occurred. MRI is useful to demonstrate the AVM in greater detail and what brain structures it is associated with. Prior to treating an AVM a cerebral angiogram using a catheter through the wrist or the groin is necessary to better demonstrate the detail of the AVM vessels and plan for treatment.
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Treatment of AVMs depends on the AVM size, location within the brain, evidence of bleeding and symptoms. Treatment options include surgery with microsurgical disconnection and resection of the AVM, and radiation therapy such as stereotactic radiosurgery. In select cases treatment may also include endovascular embolization to block blood flow in the AVM.
Moyamoya Disease
Moyamoya disease is a rare disease of the brain arteries where the carotid artery becomes thickened and blocked, with reduced blood flow to the brain. The disease affects children and younger adults and is more common in East Asian countries. The disease may cause stroke and in some cases, brain bleeding. With frequent strokes it can cause neurological problems such as cognitive impairment.
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Moyamoya disease presents with stroke or transient ischaemic attacks (TIAs) due to reduced blood flow. These symptoms can include headache, seizures, face or limb weakness or paralysis, limb numbness, difficulty speaking, involuntary limb jerking, difficulty speaking. These are usually triggered in dehydration, heat exposure or extreme exercise. Patients can also present with headache and neurological change from haemorrhage.
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CT scan and CT angiography can be useful as a screening test using x-rays and intravenous dye injection. MRI uses magnets to create detailed imaging of brain tissue and the brain arteries. It can demonstrate the abnormal moyamoya vessels as well as show stroke and evidence of reduced blood flow with special imaging techniques called perfusion imaging. A cerebral angiogram is critical to make the diagnosis of moyamoya disease. A catheter is inserted into the wrist or groin this is used to inject dye into the blood vessels of the brain to show the moyamoya disease and plan for treatment.
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Moyamoya treatment is aimed to reduce symptoms and prevent future strokes. This can be achieved with medical treatment including blood thinning medication such as aspirin and a vascular stabilization with a statin. In symptomatic disease with evidence of strokes revascularization surgery may be indicated such as bypass surgery using a scalp artery and connecting this to the surface of the brain to the middle cerebral artery. This treatment is effective in reducing stroke rates dramatically.
Aneurysms
A brain aneurysm is a weak wall in an artery in the brain which causes it to bulge. Common types of aneurysms include saccular or berry aneurysms, which are sacs that protrude from artery branching points. Brain aneurysms are common, and most are not serious. Some aneurysms can rupture and cause subarachnoid haemorrhage, which is a serious and potentially life-threatening condition.
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Unruptured brain aneurysms commonly do not cause symptoms. If an aneurysm ruptures it is a serious condition and typically causes severe headache, nausea and vomiting, neck stiffness, blurred or double vision, light sensitivity, loss of consciousness, confusion or seizure. Larger unruptured aneurysms may press on surrounding brain tissues and nerves and can cause pain, abnormal pupil changes, double vision, facial numbness or seizures.
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CT scans and CT angiography are used to assess for bleeding in the brain and to obtain detailed images of the brain’s arteries using injected dye into the vein. MRI uses magnetic fields to provide high quality images of the brain and can also be used to depict the aneurysm and brain arteries using MR angiography. A cerebral angiogram may also be necessary where a catheter is inserted into the groin or the wrist into the arterial system and used with x-rays to obtain high quality pictures of the aneurysm and blood vessels. A lumbar puncture or spinal tap may also be necessary to determine whether the patient has had an aneurysm haemorrhage by sampling the cerebrospinal fluid.
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In cases of rupture, the aneurysm usually requires urgent treatment using surgery or endovascular treatment. In unruptured aneurysms many factors are considered including the aneurysm size, shape and location, the patient’s age and other health problems and family history of aneurysms and rupture. Treatment of aneurysms include surgical clipping with opening the skull and locating the blood vessel and placing a clip across the aneurysm neck. Endovascular treatment is a less invasive alternative where small catheters are navigated to the aneurysm through the arteries using xray guidance. Endovascular treatments include coiling of aneurysms, stenting of aneurysms, and flow diversion. It is necessary to assess each individual patient to provide a tailored treatment plan to best address the aneurysm.
Dural Arteriovenous Fistulae
Dural arteriovenous fistulae (dAVFs) are abnormal connections between the arteries and veins within the coverings of the brain or spinal cord (the dura mater). This is a rare condition and usually affects patients over the age of 50. They are usually acquired conditions and develop over time. In severe cases they can be a cause of brain bleeding.
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Some patients with dAVFs may not have symptoms. In mild dAVFs they can present with pulsatile sounds (tinnitus) or may develop changes in vision, double vision, and increased eye pressure. In severe disease forms patients have a higher risk of brain bleeding and haemorrhagic stroke. Patients can also present with movement disorders or changes in thinking ability (cognition).
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CT scanning can show brain bleeding caused by aggressive dAVFs. MRI demonstrates the location of the dAVF with reference to brain tissue and can show the vascular anatomy of the dAVF. A cerebral angiogram using a catheter via the wrist or the groin and injecting dye is the best way to diagnose and determine the appearance and classification of the dAVF and is necessary for treatment planning.
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Treatment of the dAVF is indicated in higher risk forms and those with disabling tinnitus. Endovascular embolization of dAVFs is the most common treatment and involves navigating a small tube (catheter) into the fistula from the wrist or groin and blocking the connection between the artery and vein using glue or coils. Surgical disconnection may be necessary in situations were it is not possible or too high risk to treat using endovascular techniques. Stereotactic radiosurgery or medical therapy may be necessary in cases of multiple recurrent fistulae.
Cavernoma
Cavernomata are vascular malformations that are collections of dense small blood vessels with thin walls. They can occur within both the brain, brainstem and spinal cord. They vary in size. Usually, they are sporadic, but they can be associated with genetic conditions that may be inherited.
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Although cavernomata can be asymptomatic, they may leak and lead to bleeding within the brain or spinal cord. Brain haemorrhages can lead to neurological deficits or stroke-like symptoms depending on the location of the cavernoma. With repeated bleeding episodes within the brain, they can lead to seizures and long-term epilepsy. Symptoms can worsen over time with repeated episodes of bleeding. Severe, life-threatening, large bleeds from cavernomata are very rare.
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Diagnosis of cavernomata involves imaging in the form of MRI of the brain or spine. This can demonstrate the cavernoma and evidence of bleeding. This is useful to characterise the cavernoma, ongoing monitoring and for treatment planning. Genetic testing in patients with multiple cavernomata or a strong family history can be useful to identify inherited genetic disease forms.
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Treatment is available for patients with cavernomata with repeated bleeding episodes that cause neurological problems or seizure disorders. Microsurgical resection of the cavernoma may be possible in some cases and is the main treatment to prevent further bleeding episodes.
Chronic Subdural Haematoma
Chronic subdural haematoma is a collection of blood and fluid on the surface of the brain that occurs under the outer covering of the brain (the dura). It usually develops slowly over weeks and may be associated with a minor head injury. It occurs predominantly in older adults or patients who are taking blood-thinning medication. The haematoma can cause pressure on the underlying brain, and this can lead to symptoms that gradually worsen if left untreated.
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Gradually worsening headache
Confusion, cognitive and memory problems or changes in personality
Drowsiness or difficulty concentrating
Weakness, numbness, or clumsiness in the arms or legs
Problems with speech
Poor balance
Seizures and loss of consciousness
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Based on clinical examination of symptoms and patient neurological function
CT and MRI scans of the brain are used to demonstrate the collection of the blood
CT angiography can be useful for procedural planning
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Conservative management can be used with repeat CT scanning in small haematomas in asymptomatic patients
Surgery
The traditional treatment for chronic subdural haematoma
Small holes (burr holes) are made in the skull to drain the blood and fluid
Sometimes it is necessary to make a larger opening (craniotomy) particularly in complex haematomas with membranes or thicker blood products
A temporary drain may be left in place for 1 to 2 days to help prevent re-accumulation
Most patients improve significantly with surgery but there are risks with surgery including rebleeding
Middle meningeal artery embolization
A newer, minimally invasive procedure performed by a neuro-interventional specialist or endovascular neurosurgeon
A thin tube (catheter) is inserted into the artery via the groin or wrist into the middle meningeal artery in the dura, which supplies the haematoma
Following angiography, tiny particles or glue is injected to block the artery and reduce blood flow that increases the haematoma
Can be used in selected cases or in addition to surgery to reduce the risk of recurrence
Recovery is usually quicker than with open surgery
Is generally safe but there is a low risk of complications such as stroke and visual problems
Tinnitus
Tinnitus is the perception of a sound in the ears or head that is described as ringing, buzzing, humming, or whooshing. While it is often mild and related to hearing loss or ear conditions treated by an ear and nose specialist, it can be due to abnormal blood flow in the blood vessels near the ear or brain (called pulsatile tinnitus).
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Persistent or intermittent sounds in one or both ears
The noise is described as ringing, buzzing, humming, or roaring
Can be pulsatile in nature with a rhythmic sound that coincides with the patient’s pulse
The sound may change with head position or pressure on the neck
May be accompanied with hearing loss, ear fullness, dizziness, or headache
In severe forms can affect the patient’s sleep, concentration or mood
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Evaluation of tinnitus aims to identify the cause and rule out serious conditions
Clinical assessment is important with often a review by your local doctor and an ear and nose specialist
Hearing tests with audiometry may be necessary
Imaging studies may be necessary and include:
MRI or CT scans of brain and blood vessels to look for vascular causes of tinnitus
CT or MR angiography or venography to assess arteries and veins near the ear and skull base
Catheter angiography performed by a neurointerventional radiologist or endovascular neurosurgeon may be used if a dural arteriovenous fistula or venous sinus stenosis or diverticulum is suspected
Further invasive studies such as venous sinus pressure measurements may be required
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Treatment depends on the underlying cause and the impact of tinnitus on the patient’s quality of life
General management (usually performed by an ear and nose specialist)
Treat underlying ear conditions (e.g. infection, wax, hearing loss)
Sound therapy, hearing aids, or tinnitus retraining therapy
Avoidance of loud noises and managing cardiovascular risk factors
Neurointerventional radiology or endovascular procedures (for vascular pulsatile tinnitus)
Some forms of pulsatile tinnitus are caused by abnormal connections or narrowing in blood vessels near the brain or ear
Dural arteriovenous fistulae – abnormal connections between arteries and veins in the coverings of the brain endovascular embolization or blocking of the fistula can often eliminate the tinnitus completely
Venous sinus stenosis or venous diverticula or outpouchings – tinnitus occurs because of disordered venous blood drained from the brain and sometimes venous stenting can restore normal blood flow and eliminate or reduce the tinnitus
Vascular tumours such as a paraganglioma or glomus tumour can cause tinnitus due to the high blood flow and shunting between arteries and veins embolization and surgery can reduce this flow and often reduce tinnitus
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