醫學筆記匯整 ED Notes

Acute Vestibular Syndrome (AVS)
- Acute onset, continuous vertigo, dizziness, or unsteadiness
  lasting days to weeks
- Generally including features suggestive of new, ongoing vestibular system dysfunction
  (eg, vomiting, nystagmus, and postural instability).
- t-EVS is largely asymptomatic at rest
  and specific head motions induce transient dizziness
  (再次強調Triggering and Exacerbating 的差別)

 

 創傷/毒性急性頭暈 (t-AVS) Traumatic/Toxic AVS 
- 這一類的頭暈, 有時原因很明顯 The key exposures are usually obvious
- Most common causes are
  Blunt head injury and drug intoxication (particularly anticonvulsants or aminoglycoside)
- Single, acute attack resolving gradually over days to weeks
  once the exposure has stopped.
- 酒精中毒, 一氧化碳中毒, 要注意近期的用藥
- cerebrovascular concern 是怕被 t-AVS 給 mask 掉

稍微舊一點的另一個分類是分成 CVS 

 自發性急性頭暈 (s-AVS)   
　
- Usually still symptomatic at the time of assessment
- Bedside eye examination for differentiating between central and peripheral causes

- 大多數都是因為前庭神經炎 Vestibular neuritis, Labyrinthitis
  但是也有 10~20% 的人是因為中風所致 (typically brain stem or cerebellum, 95% ischemic)
  第三名原因是 Multiple sclerosis 

- Thiamine deficiency and listeria encephalitis
- HINTS + Hearing test by finger rubing rules out stroke more accurately than early MRI
   再加上 Unable to sit or stand, Obvious CNS signs 等
   有這些異常就要認真考慮後循環中風的可能 
 

 Pitfalls and Pearls 

- Cerebrovascular disorders frequently present with true vertigo symptoms
  不要以為 true vertigo 一定是內耳問題
  Focus on timing and triggers, rather than type ! 

- Triggers 不同於 exacerbating factors
   Worse with head movement 是 exacerbating factors, 不代表 peripheral cause
   Acute dizziness/vertigo 常常因頭部動作而 exacerbated (whether peripheral or central)

- Lateral pontine and inner ear strokes often cause tinnitus or hearing loss
   中風也可能造成 tinnitus or hearing loss
   Auditory symptoms 不代表是 peripheral cause

- Headaches + dizziness 不能診斷 vestibular migraine
  要搭配 headache characteristics and associated symptoms (photophobia)
  Sudden, severe, or sustained pain in the head or neck may
  indicate aneurysm, dissection, or other vascular pathology

- Isolated vertigo is the most common vertebrobasilar warning symptom before stroke
  Isolated vertigo 就可能是 TIA symptoms

- < 20% of stroke patients presenting with AVS have focal neurological signs.
  所以不是都有 focal neurological signs
  NIH stroke scales of 0 occur with posterior circulation strokes

- 年輕病人 migraine 多, 但也要考慮 vertebral artery dissection
  Vertebral artery dissection mimics migraine closely

- CT 對 Posterior fossa stroke sensitivity 不夠好
- ICH rarely mimics benign dizziness or vertigo presentations.
  Only 2.2% of ICH presented with dizziness or vertigo
  and only 0.2% presented with isolated dizziness
  所以 isolated acute dizziness or vertigo 並不需要 CT to rule out ICH 

- MRI-DWI in the first 24h misses 15-20% of posterior fossa infarctions.
  MRI-DWI sensitivity for brain stem stroke is maximal 72–100h after infarction