国产热热热精品,亚洲视频久久】日韩,三级婷婷在线久久,99人妻精品视频,精品九热人人肉肉在线,AV东京热一区二区,91po在线视频观看,久久激情宗合,青青草黄色手机视频

Imagined smells can precede migraines

Updated: 2011-10-17 10:46

(Agencies)

  Comments() Print Mail Large Medium  Small 分享按鈕 0

Hallucinated scents such as a burning or rotten smell, or even the scent of foie gras, can be a part of the "aura" that some people perceive before a migraine attack, although it is rare, according to a US study.

About 30 percent of people with recurrent migraines have sensory disturbances shortly before their headache hits, known as aura, but these are usually visual, such as flashes of light or blind spots. Tingling sensations or numbness, or difficulty speaking or understanding language, may also appear.

But the study, conducted by Matthew Robbins and colleagues at the Montefiore Headache Center in New York, found that a small number of people described smelling scents in conjunction with their headaches.

"It's uncommon, but distinctive," said Robbins, noting that disturbances in the sense of smell, known as olfactory hallucinations, have not been covered in a systematic review of medical literature before.

Researchers reviewed 25 reported cases of patients with headaches, migraines in most cases, and olfactory hallucinations. They also examined records from more than 2,100 patients seen over 30 months. Fourteen people, or just under 0.7 percent, had described smelling scents ahead of their headaches.

"The most common was of the burning or smoke variety," Robbins said.

Some sufferers described a general burning smell. Others said they smelled cigar smoke, wood smoke or burnt popcorn.

"Decomposition" odors, such as garbage or sewage, were the next most common smell reported. A few people described pleasant odours, including the scent of oranges, coffee or, in one case, foie gras.

About 11 percent of the world's population suffers from migraines, so even though olfactory hallucinations are an unusual part of aura, there could still be a fairly large number of people who experience them, Robbins said.

It's not clear why the hallucinated odors are most often unpleasant, or why they are only rarely part of migraine aura.

But aura symptoms are thought to involve a phenomenon called "cortical spreading depression," where a wave of increased electrical activity in nerve cells of the brain is followed by a wave of depressed activity, Robbins said.

That same phenomenon might underlie olfactory hallucinations -- and because the brain's smell centres occupy much less space than its sight centres, that could, in theory, explain why phantom scents are so much less common, he added.

It is also possible that some people with migraines and olfactory hallucinations do not recognise the phenomenon, he added. People know something is wrong when they see zigzag lines, but it is easy to assume a small is actually coming from somewhere.

Since some disorders, such as Parkinson's disease, can cause a person to smell scents that are not present, any such hallucinations without an accompanying headache should be checked out, he warned.

益阳市| 惠东县| 永平县| 疏附县| 略阳县| 宜宾市| 内乡县| 乌拉特中旗| 马关县| 上蔡县| 南宫市| 宣汉县| 铜山县| 洛南县| 寿宁县| 竹北市| 阳江市| 枣强县| 紫金县| 大兴区| 阳东县| 涿鹿县| 龙山县| 龙胜| 长葛市| 洛浦县| 梁山县| 玛多县| 马鞍山市| 咸阳市| 锦州市| 通山县| 班玛县| 蛟河市| 栖霞市| 西畴县| 东乡| 淳安县| 巫溪县| 观塘区| 新绛县|