p.49 抽出テキスト

.................................... stenosis or occlusion of the subclavian artery. A TIA may occur when flow through the vertebral artery cannot supply both the arm and part of the brain during forceful use of the arm. Steal most often affects the left side. When detected with ultrasound, steal is asymptomatic in 64% of cases.422 A TIA is likely due to steal only when it is vertebrobasilar (see below) and associated with exercise of one arm. There are no reliable reports of isolated LOC without focal neurological symptoms and signs in subclavian steal.

A TIA related to a carotid artery does not usually cause TLOC. An exception concerns orthostatic TIAs, concerning a combination of multiple stenoses of cerebral arteries and OH. This may rarely result in repetitive, orthostatic, short-lasting, and stereotyped TIAs.423,424 A TIA of the vertebrobasilar system can cause LOC, but there are always focal signs, usually limb weakness, gait and limb ataxia, vertigo, diplopia, nystagmus, dysarthria, and oropharyngeal dysfunction. Fewer than 1% of patients with vertebrobasilar ischaemia present with a single presenting symptom.425

8.1.4 Migraine Syncope, presumable VVS, and orthostatic intolerance occur more often in patients with migraine, who have a higher lifetime prevalence of syncope and often frequent syncope.426 In migraineurs, syncope and migraine attacks rarely occur simultaneously.

Table 10 Differentiating syncope from epileptic seizures9,50,410,411

Clinical feature Syncope Epileptic seizures

Useful features

Presence of trigger Very often Rare

Nature of trigger Differs between types: pain, standing, emo-

tions for VVS; specific trigger for situational syncope; standing for OH Flashing lights is best known; also range of rare

triggers

Prodromes Often presyncope (autonomic activation in

reflex syncope, light-headedness in OH, palpitations in cardiac syncope) Epileptic aura: repetitive, specific for each patient.

Includes de ́ja vu. Rising sensation in the abdomen (epigastric aura) and/or an unusual unpleasant smell

Detailed characteristics of myoclonus • <10, irregular in amplitude, asynchronous,

asymmetrical • Starts after the onset of LOC • 20–100, synchronous, symmetrical, hemilateral • The onset mostly coincides with LOC • Clear long-lasting automatisms as chewing or lip

smacking at the mouth

Tongue bite Rare, tip of tongue Side of tongue (rarely bilateral)

Duration of restoration of consciousness 10–30 seconds May be many minutes

Confusion after attack No understanding of situation for <10 seconds

in most syncope, full alertness and awareness afterwards Memory deficit, i.e. repeated questions without

imprinting for many minutes

Features of limited utility

Incontinence Not uncommon Common

Presence of myoclonus (see below for nature of myoclonus) Very often 60%, dependent on accuracy of observation

Eyes open during LOC Frequent Nearly always

Fatigue and sleep afterwards Common, particularly in children Very common

Blue face Rare Fairly often

LOC = loss of consciousness; OH = orthostatic hypotension; VVS = vasovagal syncope. Downloaded from academic.oup.com/eurheartj/article/39/21/1883/4939241 by guest on 07 October 2026