Newsletter No. 377

2 No. 377, 4.5.2011 中風小資料 What Is Stroke? 中風醫學名稱為「腦血管疾病」，是因腦部的血液供給因某些原因而減少或阻斷，令腦細胞突然缺氧，數分鐘內可令腦細胞損壞而失去功能， 可能導致半身不遂、言語不清、吞嚥困難、大小便失禁、感覺麻木，嚴重者甚至昏迷或死亡。 The medical term of stroke is ‘cerebral vascular accident’. It occurs when blood supply to the brain is reduced or blocked for certain reasons, leading to a sudden lack of oxygen in brain cells. In a few minutes, brain cells may be damaged and lose their functions. Stroke may cause paralysis on one side, difficulty in talking and swallowing, incontinence, impairment of sensation, coma or even death. 為中風病人 帶來新生 — 黃家星教授 Bringing New Life to Stroke Patients — Prof. Lawrence K.S. Wong 腦 是取代不了的器官，心臟可以換、肝可以、腎可 以，唯獨腦不可以。」縱然腦是人體的主宰，但 人類對它的認知只是皮毛，腦疾病的治療更偏向消極，以 中風為例，公眾甚至醫護人員向來均認為「做不到甚麼」， 直至黃家星教授的突破性研究為中風病人帶來新希望。 最近獲頒裘槎基金會2011 – 12年度「優秀醫學科研學者 獎」的內科及藥物治療學系莫慶堯內科醫學講座教授、腦 神經科主任黃家星，二十多年前已開始研究中風，他說雖 然中風是香港的第三號殺手，排在癌病及心臟病之後，但 卻是導致永久傷殘的頭號成因，會令病人不能維持一向 的生活質素，並為照顧者帶來沉重壓力，這是此病的可怕 之處。 透過超聲波、磁力共振掃描等技術，黃教授大規模檢查了 五六千名本地及內地病人，並率先確定顱內動脈粥樣硬化 （腦血管收窄）是亞洲中風患者最常見的血管病變，而西 方人中風的主因則是頸部血管狹窄。 了解病因後，黃教授就研究利用支架（ 右圖 ）將中風病人 腦血管狹窄部分撐開，減低病人再次中風的風險。該項微 創手術要在大腿動脈開啟一個切口，以影像引導，透過微 型導管將支架沿血管運送到顱內動脈的狹窄部分，以擴 大血管口徑和維持暢通，「這遠較在心臟安裝支架複雜， 從大腿到心臟很近，血管也較直，但腦血管較彎曲，導管 要繞多個圈才可到達目的地，加上收窄後的血管直徑只有 一毫米，故手術要求很高技巧。」 此外，腦血管由腦髓液包圍，附近沒有肌肉，甚為脆弱，如 將血管一舉擴大，很容易令血管破裂。「剛巧數年前外國 研發了一種有記憶力的合金物料，製成支架，放進腦血管 中，它最初只會擴大至所需口徑的七八成，然後在往後數 星期慢慢膨脹至目標直徑的大小，這樣便安全多了。」 中大是美國以外第一個做腦血管支架手術的地方，迄今 已做了近一百宗，併發症發生率很低，接受手術的除了參 加研究的本地病人外，還有從印度、馬來西亞慕名而來的 病人。 黃教授來年將全力投入研究工作。除了支架手術，他亦會 繼續研究利用儀器增加腦的血流量，以改善血管內壁功 能，以及作中風的臨床藥物研究，希望可為中風病人帶來 更多福音。 看着病人身體機能逐漸改善，黃教授心中甚感欣喜。「昔 日控制自如的身體，忽然失去功能，經過治療重拾以往的 活動能力，這對他們來說有種重生的感覺。」 ‘T he brain is an irreplaceable organ. We can transplant the heart, livers, kidneys, but never the brain.’ The brain is the headquarters of the human body but our knowledge of it is so superficial. The treatment for brain diseases was passive. Take stroke, for example, the public, even medical practitioners always believe that little can be done to treat stroke patients. It was not until Prof. Lawrence K.S. Wong made a breakthrough in stroke treatment that stroke sufferers began to see the light at the end of the tunnel and have fresh hope. Professor Wong, Mok Hing Yiu Professor of Medicine, Chief of Neurology, Department of Medicine and Therapeutics, has studied stroke for two decades, and was recently awarded the Senior Medical Research Fellowship 2011–12 of the Croucher Foundation. Stroke is the number three killer disease in Hong Kong after cancer and heart disease, and the main culprit for disability. The frightening disease will make self-sustaining individuals lose quality of life and cause great stress to caregivers. By applying new techniques such as ultra-sound and magnetic resonance imaging, Professor Wong has conducted a large-scale screening for 5,000 to 6,000 local and mainland stroke patients. He is the first to confirm that the most common cause of stroke in Asian patients is intracranial atherosclerosis (narrowing of vessel around the brain), while that in western countries is the narrowing of the vessel in the neck. After pinpointing the cause, Professor Wong studied the technique of stent-assisted angioplasty of the brain vessel to minimize the rate of recurrent stroke. The minimally invasive procedure involves transporting a wire mesh tube (a stent, left photo ) from large supra-aortic arteries to minute intra-cranial arteries through an incision at the groin by means of a small catheter and with the help of imaging tools. The stent will form a rigid support to hold the artery open. ‘This procedure is much more complex than coronary artery stenting. The distance between the thigh to the heart is relatively short and the artery path is quite straight. By contrast, the cerebral vessel has many twists and turns and the narrowed one has a diameter of only 1mm. Complete technical mastery is a must.’ The cerebral vessel is surrounded by cerebrospinal fluid instead of flesh. It is very fragile and may burst if overly expanded. ‘Since a few years ago, stents made of shape memory alloys have been available. Stents made of this new material will expand to 70–80% of the required diameter when put into the cerebral vessel and expand gradually to the designated size in the following weeks. This is much safer.’ CUHK is the first centre outside the US to perform the stent-assisted angioplasty of the brain vessel. So far, there are about 100 successful cases with a low complication rate. In addition to the local patients who have participated in the research, many patients from overseas, such as India and Malaysia, have come to the University for the treatment. Professor Wong will devote more time and effort to research work in the years to come. In addition to stenting, he will study treatment for intracranial atherosclerosis with cerebral blood flow augmentation and drug therapy. The former can enhance the flexibility of the inner walls of blood vessels. Professor Wong is keeping his fingers crossed that the outcomes will be of benefit to stroke patients. Nothing makes Professor Wong happier than seeing the recovery of his patients. ‘After treatment, they can regain the abilities of which they were suddenly deprived. It seems like we have brought a new life to them.’ 「