HINTS for posterior circulation infarction
HINTS (head impulse- nystagmus-Test of Skew)
診斷早期 posterior circulation stroke.
HINTS test 比 MRI 更準(敏感度99%)
Kattah JC, Talkad AV, Wang DZ, Hsieh YH, Newman-Toker DE. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke. 2009 Nov;40(11):3504-10.
Screening patients with AVS for one of 3 dangerous oculomotor signs (normal h-HIT, direction-changing nystagmus, skew deviation) appears to be more sensitive than MRI with DWI in detecting acute stroke in the first 24 to 48 hours after symptom onset. These “HINTS” to “INFARCT” could help reduce frontline misdiagnosis of patients with stroke in AVS and should be studied head-to-head for their comparative cost-effectiveness against neuroimaging by MRI DWI.
1 - Patients with peripheral vertigo will have abnormal (positive) head impulse testing, while patients with central vertigo typically have a normal (negative) head impulse test.
2 - Patients with peripheral vertigo will have unidirectional, horizontal nystagmus, while patients with central vertigo can have rotatory or vertical nystagmus, or direction-changing horizontal nystagmus.
3 - Alternate eye cover testing may reveal skew deviation in patients with central vertigo, and should be absent in peripheral vertigo.
The Head Impulse Test
先緩慢左右轉動病患頭部, 再來要快速轉動約 20 度. 前庭神經發炎的那一側, 在快速轉動回正常位置時, 眼睛無法跟上. 在頭部靜止之後會繼續移動校正回預設位置(你請病患注視的點).
眩暈症的患者, 如果 head impulse test 異常. 代表前庭神經有問題. 所以可以排除腦部問題.
abnormal is good.
The clinician stands before the patient, holding the patient's head in his hands, and the patient, who is looking straight at the clinician, is asked to keep staring at the earth-fixed target (the clinician's nose). If the clinician now turns the patient’s head abruptly and unpredictably to the left or right, through a small angle (only 10-20 degrees - not a large angle), that head turn is what we call the head impulse.If the patient has a functioning vestibulo-ocular response (VOR) they will be able to maintain gaze on the target because the vestibulo-ocular response drives the eyes to rotate to exactly compensate for head rotation and so maintain fixation.
However if the patient's vestibulo-ocular response is inadequate then their eyes will be taken off target during the head rotation, because their eyes will not rotate at the correct speed to exactly compensate for head rotation. So an inadequate VOR means that the eyes go with the head during the passive unpredictable head turn and will be taken off target by the head turn, so that at the end of the head turn the patient must make a corrective saccade back to the clinician's nose. To the clinician watching the patient's eyes, this saccade is usually very clear, and we have termed it an overt saccade. It is the telltale sign of inadequate semicircular canal function on the side to which the head was rotated. So an overt saccade after a leftwards head rotation means the left semicircular canal has a deficit. If there is any doubt, the clinician just repeats the head impulses until they are satisfied.
診斷早期 posterior circulation stroke.
HINTS test 比 MRI 更準(敏感度99%)
Kattah JC, Talkad AV, Wang DZ, Hsieh YH, Newman-Toker DE. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke. 2009 Nov;40(11):3504-10.
Screening patients with AVS for one of 3 dangerous oculomotor signs (normal h-HIT, direction-changing nystagmus, skew deviation) appears to be more sensitive than MRI with DWI in detecting acute stroke in the first 24 to 48 hours after symptom onset. These “HINTS” to “INFARCT” could help reduce frontline misdiagnosis of patients with stroke in AVS and should be studied head-to-head for their comparative cost-effectiveness against neuroimaging by MRI DWI.
1 - Patients with peripheral vertigo will have abnormal (positive) head impulse testing, while patients with central vertigo typically have a normal (negative) head impulse test.
2 - Patients with peripheral vertigo will have unidirectional, horizontal nystagmus, while patients with central vertigo can have rotatory or vertical nystagmus, or direction-changing horizontal nystagmus.
3 - Alternate eye cover testing may reveal skew deviation in patients with central vertigo, and should be absent in peripheral vertigo.
The Head Impulse Test
先緩慢左右轉動病患頭部, 再來要快速轉動約 20 度. 前庭神經發炎的那一側, 在快速轉動回正常位置時, 眼睛無法跟上. 在頭部靜止之後會繼續移動校正回預設位置(你請病患注視的點).
眩暈症的患者, 如果 head impulse test 異常. 代表前庭神經有問題. 所以可以排除腦部問題.
abnormal is good.
The clinician stands before the patient, holding the patient's head in his hands, and the patient, who is looking straight at the clinician, is asked to keep staring at the earth-fixed target (the clinician's nose). If the clinician now turns the patient’s head abruptly and unpredictably to the left or right, through a small angle (only 10-20 degrees - not a large angle), that head turn is what we call the head impulse.If the patient has a functioning vestibulo-ocular response (VOR) they will be able to maintain gaze on the target because the vestibulo-ocular response drives the eyes to rotate to exactly compensate for head rotation and so maintain fixation.
However if the patient's vestibulo-ocular response is inadequate then their eyes will be taken off target during the head rotation, because their eyes will not rotate at the correct speed to exactly compensate for head rotation. So an inadequate VOR means that the eyes go with the head during the passive unpredictable head turn and will be taken off target by the head turn, so that at the end of the head turn the patient must make a corrective saccade back to the clinician's nose. To the clinician watching the patient's eyes, this saccade is usually very clear, and we have termed it an overt saccade. It is the telltale sign of inadequate semicircular canal function on the side to which the head was rotated. So an overt saccade after a leftwards head rotation means the left semicircular canal has a deficit. If there is any doubt, the clinician just repeats the head impulses until they are satisfied.
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