話說最近在看一些疼痛相關的研究報告時，總是被一些疼痛測試搞的一頭霧水，
下面列出部分常用的疼痛測試方法和模式，其中很重要的一個名詞就是QST
(quantitative sensory testing)：它包含了一堆的測試項目，節錄一些journal
的內容，希望有幫忙：
測試圖型：
摘要
關鍵詞：感覺閾；溫度覺；振動覺；心理物理學
定量感覺檢查（quantitative sensory testing，QST）是對感覺進行定量判斷的一種心理物理學技術，可以對感覺障礙的程度進行定量評價。 長期以來，臨床上判斷有無感覺障礙是依據臨床痛覺、溫度覺等檢查及電生理檢測的結果。 臨床檢查簡便、快速，但只能得出正常與否的結論，難以進行定量化，其重複性、特異性及有效性不高。 因此，雖然臨床檢查對感覺障礙的判斷是有用而且重要的，但對於疾病發展過程及治療效果等隨訪性研究有其局限性。 電生理學檢測，如感覺神經傳導，可以提供相應神經功能的客觀資料，對判斷有無感覺神經受損有一定幫助，但感覺神經傳導只能反映感覺神經中直徑大的有髓鞘纖維的功能，不能反映小直徑、薄髓鞘纖維的功能，因此對主要影響神經小纖維的病變不敏感，而且在操作和評價時需要一定的技術和經驗，另外，感覺障礙的程度與感覺神經傳導速度異常程度之間的關係亦不明確。 為了能反映感覺神經中各種纖維的功能，且比較客觀地對感覺進行判斷，早在19世紀就有定量評價感覺的概念和一些工具，隨著計算機的發展，這類檢查方法更簡單、更多樣化；Peltier原理的應用引進了直接接觸的溫度刺激器，這種刺激器比以往的輻射型的溫度刺激器更便於調節、控制溫度。 在50、60年代開始了這方面的研究，70年代把QST應用到臨床。 近20年QST引起了人們廣泛的關注，出現了多種類型的感覺檢查儀，開拓了多種QST檢查方法。 現將qST的定義、特點、方法及應用等介紹如下。
定義、特點、作用
QST指測定引起某種特定感覺所需要的刺激強度的技術[1]。 QST操作比較簡單、無創、無痛苦，因此，對受試者可進行重複測定，所獲得的資料可進行參數的統計學分析，對於大宗病例的篩選與臨床試驗的縱向隨訪研究特點有價值[2 ,3]。
感覺種類與神經纖維類型及其QST的臨床意義
神經纖維根據它的直徑、傳導速度及電記錄特性分為四種類型：A、B、C、及γ纖維。 A、B纖維又有許多亞型。 周圍神經中，振動覺和触覺、輕壓覺、關節位置覺是由大直徑、有髓鞘纖維（Aα、Aβ）傳導的；溫度及痛覺主要通過小直徑、薄髓鞘的Aδ和無髓鞘的C纖維傳導。 在中樞神經系統，振動覺、精細觸覺是由后索傳導的，溫度覺是由脊髓丘腦束傳導的[1,7]。 目前已開展的qST感覺類型有：溫度覺、振動覺、觸壓覺、電流覺。 前兩者應用較多。 定量溫度覺檢查（quantitative thermal perception testing，QTT）可檢查冷覺、溫覺、冷痛覺、熱痛覺的閾值，主要反映小纖維的功能。 振動覺、觸壓覺的閾值主要反映小纖維的功能。 在許多周圍神經病變中，可僅僅損害小纖維或僅僅損害大纖維，也可大小纖維成分同時損害，神經大纖維的功能可以通過神經傳導、定量振動覺檢查等反映，而QTT是評價軀體神經小纖維功能的唯一檢查方法，QST與神經傳導相結合，對周圍神經功能進行綜合評價可有互補作用，所以QST的研究具有臨床實用意義。
方法學
QST測定方法分為兩個基本類型：包括反應時間在內的測定方法（reaction time inclusive methods，RTIM）與不包括反應時間在內的測定方法（reaction time exclusive methods，RTEM）。
RTM 要求受試者在感覺到一個特定的感覺或者感覺消失時通過按按鈕等方法終止一個漸增或漸減的刺激。 來自刺激點的衝動經周圍神經到腦，加工以後，命令傳出到手完成終止刺激的動作，此過程所需要的時間，即反應時間。 在這段時間內刺激的強度仍在不斷變化，所以通過RTM所得閾值比RTEM所得的絕對閾值要高。
一、極限（limits）法：刺激強度從0到一個基礎溫度開始呈直線或指數性增強或減弱，直到受試者產生特定感覺而中止，一般重複刺激3～4次，得到一個平均閾值。
二、溫度覺閾區（thermal sensory limen，TSL）法：又稱'Mar stock'法。 這是臨床上最先應用的方法。 刺激的溫度在冷與熱之間變化，沒有一個基礎中止點，通過幾次冷熱閾值之間的反複測定，就得到一個閾區，即冷、溫閾值之間無感覺的一個溫度範圍。
RTEM 又稱恆定刺激法（constant stimuli method），此法包括一個事先設定的刺激強度序列，受試者不能終止刺激，每次刺激結束後刺激強度總是回復到0或基礎強度，要求受試者在接受每次刺激後作一個是與否的回答即“事後陳述”。 隨後的刺激強度的變化程度（增加或減少的輻度）是根據不同方法事先設定的；刺激方向的變化（強度增加或減少）是由受試者對前一個刺激的反應決定的，即：肯定的回答可引出一個較前小的刺激，否定的回答就引出一個較前大的刺激。
Appendix 1. Verbalinstructions for performing quantitative sensory testing.
Test 1. Thermal testing procedures (CDT, WDT, TSL, PHS, CPT, HPT).
“A temperature test of your skin will beperformed. First we are testing your ability to detect a change of temperatureto ´cool´ or ´warm´. A special device that cools or warms your skin will beplaced over your… (specifypractice area, control and test areas).Secondly another temperature test of your skin will be performed to find thetemperature that feels ´painfully cold or hot´.”
Instructions for testing of cold detectionthreshold (CDT).
“Please press the stop-button as soon as youfeel the slightest change of temperature to ´cold´. Then the thermode will warmup to starting temperature. This procedure will start in a few seconds and willbe repeated a total of 3 times.”
Instructions for testing of warm detectionthreshold (WDT).
“Please press the stop-button as soon as youfeel the slightest change of temperature to ´warm´. Then the thermode will cooldown to starting temperature. This procedure will start in a few seconds andwill be repeated a total of 3 times.”
Instructions for testing of thermal sensorylimen (TSL).
“Please press the stop-button as soon as youfeel the slightest change of temperature to ´warm´ or ´cold´, and say as you doso whether the sensation you feel is warm or cold. Then the test continuesimmediately without prior warming up or cooling down to normal skintemperature. This procedure will be repeated a total of 6 times in a row andstart in a few seconds.”
Instructions for testing of paradoxical heatsensations (PHS) during the TSL procedure.
Instructionto the investigator: Some subjects will report a sensation of “warm” or “hot”or “painfully hot” upon cold stimulation during the TSL procedure. Thesereports have to be marked as “paradoxical heat sensation”.
Instructions for testing of cold pain threshold(CPT).
“The temperature of the skin will decrease to´cold´. Eventually a painful component will be added to the sensation of ´cold´,and it will change in quality from cold to, for example, ´aching´, ´stinging´,or ´burning´. Please press the stop button immediately at the first painfulsensation. After pressing the stop-button the thermode will warm up to startingtemperature. This procedure will start in a few seconds and will be repeated atotal of 3 times.”
Instructions for testing of heat pain threshold(HPT).
“The temperature of the skin will increase to´warm´ and a few moments later to ´hot´. Eventually a painful component will beadded to the sensation of ´hot´, and it will change in quality from ´hot´ to,for example, ´burning´ or ´stinging hot´. Please press the stop-buttonimmediately at the first ´burning´ or ´stinging hot´ sensation. Then thethermode will cool down to starting temperature. This procedure will start in afew seconds and will be repeated a total of 3 times.”
Test 2. Testing of the mechanical detection threshold (MDT).
“This is a test of your ability to detect light touch. I will press these hairs to your skin (specify practice area, and control and testareas). Please say ´Yes´, if you feel the slightest light touch.”
The mechanical detection threshold (MDT) was measured with a standardized set of modified von Frey hairs (Optihair2-Set, Marstock Nervtest, Germany) that exert forces upon bending between 0.25 and 512 mN graded by a factor of 2 (1–2 s contact time). The contact area of the von Frey hairs with
the skin was of uniform size and shape (rounded tip, 0.5 mm in diameter) to avoid sharp edges that would facilitate nociceptor activation. Using the ‘‘method of limits’’, five threshold determinations were made, each with a series of ascending and descending stimulus intensities. The final threshold was the geometric mean of these five series.
Test 3. Testing of the mechanical pain threshold (MPT).
“This is a test of your ability to detect asensation of ´pricking´ or ´stinging´. Blunt needles that increase in sharpnesswill be pressed gently against your skin (specify practice area, and control and test areas). At first you may be able to feel them, but not feel that they are ´pricking´ or ´stinging´ in any way. However,eventually a component of slight ´pricking´ or ´stinging´ will be added to this sensation. Please say “sharp”,immediately as you feel the slightest ´pricking´ or ´stinging´ sensation! If you feel the needle touching your skin without any ´pricking´ or ´stinging´,please say “blunt”.
The mechanical pain threshold (MPT) was measured using custom-made weighted pinprick stimuli as a set of seven pinprick
mechanical stimulators with fixed stimulus intensities (flat contact area of 0.2 mm diameter) that exerted forces of 8, 16, 32, 64, 128, 256,and 512 mN. The stimulators were applied at a rate of 2 s on, 2 s off in an ascending order until the first percept of sharpness was reached. The final threshold was the geometric mean of five series of ascending and descending stimuli. This test was designed to detect pinprick hypoalgesia.
Test 4. Testing of stimulus-/response-functions(MPS and ALL).
“This is a test of your ability to feel different intensities of pain. As in the previous test, blunt needles that increase in sharpness will be pressed gently against your skin. In between you will be touched by gently moving stimuli. Some of these stimuli will be accompanied by a sensation that has a ´pricking´, ´burning´ or ´scraping´quality, some may not be ´pricking´, ´burning´ or ´scraping´ at all, and someyou may not even be able to detect. Please give a number between ´0´ and ´100´for the ´prickingness´, ´sharpness´ or ´strongness of the burning or scraping sensation´ of each stimulus.
´0´ indicating no pain or any kind of´slightly pricking, stinging, burning or scraping sensation´.
´100´ indicating mostintense pain, pricking, stinging, burning or scraping imaginable.”
Mechanical pain sensitivity (MPS) was assessed using the same set of seven weighted pinprick stimuli to obtain a stimulus–response function for pinprick-evoked pain (the strongest pinprick force was about eight times the mean mechanical pain threshold). Subjects were asked to give a pain rating for each stimulus on a ‘0–100’ numerical rating scale (‘0’ indicating‘‘no pain’’, and ‘100’ indicating ‘‘most intense pain imaginable’’).This test was designed to detect pinprick hyperalgesia.
Dynamic mechanical allodynia (ALL) was assessed as part of the test above, using a set of three light tactile stimulators as moving innocuous stimuli: Cotton wisp exerting a force of 3 mN, a cotton wool tip fixed to an elastic strip exerting a force of 100 mN, and a standardized brush (Somedic, Sweden) exerting a force of 200–400 mN. The tactile stimuli were applied with a single stroke of approximately 2 cm in length over the skin. These stimuli were inserted into the balanced protocol in between the pinprick stimuli.
A total of 50 stimuli, 15 tactile and 35 pinprick, were delivered at each site with the subject giving numerical pain ratings for each stimulus. These stimuli were given in runs of 10 (five runs per test site), and each run consisted of a different pseudorandom sequence of three tactile and seven pinprick stimuli.
All stimuli were applied with a 10 s inter-stimulus interval – well below the critical frequency for wind-up. Mechanical pain sensitivity was calculated as the geometric mean of all numerical ratings for pinprick stimuli. Dynamic mechanical allodynia was calculated as the geometric mean (compound measure) of all numerical ratings across all three different types of light touch stimulators.
Test 5. Performing the ´wind-up´ procedure (WUR).
“This is a test of repeated pinpricks, usingthe same kind of blunt needle that was used in the last two tests. I will nowapply a single pinprick. Please give a number between ´0´ and ´100´ for the´prickingness´ or ´sharpness´ of that stimulus.
´0´ again indicating no pain or any kindof ´slightly pricking or stinging sensation´.
´100´ indicating most intense pain,pricking or stinging imaginable.”
Continue,when the subject has rated the single pinprick stimulus:
“I will now apply a series of 10 pinpricks in arow. Please give a number between ´0´ and ´100´ for the prickingness orsharpness over that whole series of 10 pinpricks.
´0´ indicating no pain or any kind of´slightly pricking or stinging sensation´.
´100´ indicating most intense pain imaginable.”
Test 6. Testing of the vibration detection threshold (VDT).
“This is a test of your ability to detectvibration. Now I will put this tuning fork, once I have made it vibrate, onyour… (specifypractice area, control and test areas, and place the tuning fork over a bonypart of the referring area). Please tellme if you feel any vibration, and say ´Now´immediately that this vibration disappears. This procedure will be repeated atotal of 3 times.”
Test 7. Testing of the pressure pain threshold (PPT).
“This is a test of your sensitivity to deeppain. Now I will press this pressure meter against your… (specify practice area, and controland test areas), and will graduallyincrease the pressure. Please say ´Now´as soon as the pressure starts to be painful. This procedure will be repeated atotal of 3 times.”
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