Work-related Carpal Tunnel Syndrome

王賢和 MD.PhD職業醫學科

Case - M/48

季 xxCC: referral here under the impression of work related carpal tunnel syndrome.

職業病的診斷原則1.疾病的證據2.職業暴露的證據3.符合時序性4.符合人類流行病學已知的證據5.排除其他可能的致病因素

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罹病的證據1. Symptoms2. Signs3. Tests

SYMPTOMS

1. Numbness,

2. Tingling pain in the volar aspects of hands

3. Weakness in left hand gripping

4. Especially noted after work or at night

5. Shaking hands to relieve the pains

• No sleep disturbance yet

Signs

1. Tinel's sign (+/-): tapping over the median nerve at the wrist causes paresthesias or pain radiating from the wrist to the thumb and the index, the middle and half the ring fingers.

2. Phalen‘s test (+/-): bending the wrist forward all the way for 60 seconds results in numbness, tingling, or weakness in a median nerve distribution

• Atrophy of the thenar muscles (-)

Present illness1. Numbness, tingling pain and weakness of

hands for 3 years2. Pain could temporarily relieved by the

analgesics, traditional massages, herb medicines and local steroid injection.

3. Carpal tunnel syndrome was diagnosed at the賢德 hospital on 2011/01/07.

4. Referral under the impression of work related disease.

Motor Nerve Conduction Study

1. Normal amplitude2. Delayed distal latencies of bilateral median

nerves.3. Prolong F latencies of bilateral median

nerves in F wave study 4. Normal results of ulnar, peroneal and tibial

nerves.

F wave study

• Supra-maximal stimulation

• Ortho-dromic stimulus M wave: muscle contraction.

• Anti-dromic stimulus the motor neuron cell bodies backfire down towards the muscle small F wave.

F-wave study

• D = the length from the stimulation (wrist crease) to the spine (C7) (for median nerve) .

• F-M = the latency difference between mean F and M

• Delay = 1 millisecond

• Conduction velocity = 2D/(F-M-1).

Sensory Conduction Study

1. Slowing in the palm-wrist conduction of bilateral median nerves

2. Normal results of ulnar and sural nerves.

Nerve Conduction Study (NCS)

• Motor NCS • Sensory NCS• F-wave study (initially recorded in

the foot muscles)• H(Hoffmann)-reflex study

F-wave study vs. Motor and Sensory coduction studies

• The F-wave latency can be used to derive the conduction velocity of nerve between the limb and spine,

• whereas the motor and sensory nerve conduction studies evaluate conduction in the segment of the limb.

• F-wave study is not a reflex.

H reflex

• monosynaptic reflex

• electrically stimulating the tibial nerve (Ia afferents from muscle spindles), generally in the popliteal fossa,

• recording from the gastrocnemius-soleus muscle

• similar to the Achilles reflex, except that the neuromuscular spindles are bypassed.

Hoffmann reflex

1. Square-wave current of short duration and small amplitude

2. Early response on EMG: M-wave3. Later responses: H-wave (reflected). 4. As the stimulus increases, the M-wave increases and the

H-wave decreases. 5. At supramaximal stimulus, alpha fibers involved, the H-

wave disappears and the F-wave appears.

NCV Reports

• Slowing at wrist conduction of bilateral median nerves.

• Diagnosis: carpal tunnel syndrome (CTS)

Tests

• Nerve conduction velocity: positive

• Therapeutic and diagnostic challenge test: possibly positive.

• Wrist X-rays: negative

• Electromyography: nil.

Electromyography (EMG)

1. surface EMG

2. intramuscular (needle and fine-wire) EMG.

• Resting and contracting

Occupational CTS (OCTS)

職業病的診斷原則1.疾病的證據2.職業暴露的證據3.符合時序性4.符合人類流行病學已知的證據5.排除其他可能的致病因素

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工作史１1980-1984 友聯鞋業之裁剪作業員1988-1992 偉仲製帽之裁剪作業員• 工作時 , 需使用油壓機器將牛皮裁成鞋底或帽子。

• 油壓機上的裁刀常會卡於機台上 , 需用手腕施力直接拔出或拿鐵鎚 (5磅重 )用力鎚打敲鬆再拔出 . 鎚打的頻率約 20秒一次，每天持續 8小時。

工作史 -2

1992-2001 群國工程之營造工人2001-now 無固定雇主之營造工人動鑽打洞, 植筋, 砌磚 , 敲磚 , 扛鐵和粉刷等 .每天需重覆地扛起20-30公斤的鐵條並以手腕用力綑綁, 約 6-7小時 .

或使用電動鑽打洞約6小時, 每 1-2秒震動一次 .

暴露之證據• 過去擔任皮革裁剪作業員時 , 以及擔任營造勞力工作時 , 皆需經常重覆地以手腕用力地扭轉或接觸高頻震動等 .

工作場所評估：目前無固定雇主及工作場所 . 其中一次的工作現場照片如下：

職業病的診斷原則1.疾病的證據2.職業暴露的證據3.符合時序性4.符合人類流行病學已知的證據5.排除其他可能的致病因素

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時序性1980-1992 裁剪皮革1992–now營造工作 , 砌磚 , 粉刷 , 鋼筋組合 , 植筋 , 敲磚和電動鑽打洞等。

於 2008 年開始出現雙手腕酸痛、無力和麻的情形

職業病的診斷原則1.疾病的證據2.職業暴露的證據3.符合時序性4.符合人類流行病學已知的證據5.排除其他可能的致病因素

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Reviews

1. The median nerve is formed from parts of the medial and lateral cords of the brachial plexus.

2. It continues down the arm to enter the forearm with the brachial artery.

3. It originates from the brachial plexus with roots from C5, C6, C7, C8, & T1.

Carpal Tunnel Syndrome

1. Median nerve compression at the wrist is the most common peripheral nerve entrapment disorder.

2. Constellation of specific symptoms and signs, described as CTS.

3. Annual incidence in the general population = 1/1000

Epidemiology of CTS

1. most often in people 30 to 60 years old

2. more common in women than men.

3. common in people who perform repetitive motions of the hand and wrist.

Repetitive motions of the hand and wrist

• Typing on a computer keyboard

• Sewing

• Driving

• Assembly line work

• Painting

• Writing

• Use of hand tools that vibrate

• Sports such as racquetball or handball

• Playing some musical instruments

Work-related CTS

• most often associated with activities requiring extensive, forceful, repeated, or prolonged use of the hands and wrists,

1. (NIOSH Publication no. 97–141.US Department of Health and Human Services, 1997)

2. (Palmer KT et al.Occup Environ Med 2007; 57:57–66) 。

職業性腕隧道症候群工作時 , 手腕必須1. 經常反覆地動作 ,2. 經常持續地以一種不自然的姿勢工作 ,3. 或經常用力地作出扭轉的動作等長時間累積的傷害造成① 手腕部軟組織的病變或功能異常 ,② 以及造成附近肌腱的發炎和週邊神經之壓

迫 .

Occupational Carpal Tunnel Syndrome (OCTS)

1. Forceful hand use, particularly if repeated for prolonged periods

2. Constant firm gripping of objects

3. Moving or using the hand and wrist against resistance or with force

4. Exposing the hand and wrist to strong regular vibrations

5. Regular or intermittent pressure on the wrist

Work Exposures and the Probability of Work-Relatedness

Exposure Examples of types of jobs Probability of work-relatedness

Combinations of high force with high repetition and awkward posture; regular strong vibrations

Seafood, fruit, or meat processing or canning, carpentry, roofing, dry-wall installation, boat building, book binding

High, Relative risk > 4

Medium-high force, high repetition or awkward posture alone, on a nearly continuous basis

Dental hygienists, wood products production

Medium, Relative risk 2-4

Low force or medium-low repetition alone, on an intermittent basis

Computer or keyboard use

Low, Relative risk < 2

職業病的診斷原則1.疾病的證據2.職業暴露的證據3.符合時序性4.符合人類流行病學已知的證據5.排除其他可能的致病因素

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過去病史1.過去無手部的重大外傷、痛風、甲狀腺

疾病、痛風、自體免疫疾病糖尿病和關節炎等可能會造成腕隧道症候群之相關病史。

2. 2011 年曾由鷹架跌落，胸部挫傷，但未傷及手部。

Risk factors for CTS

1. inflammatory or non-inflammatory arthropathies,

2. recent or remote wrist trauma or fractures,

3. diabetes mellitus,

4. obesity,

5. hypothyroidism,

6. pregnancy,

7. genetic factors.

Medical problems associated with CTS

• Fracturesand arthritis of the wrist

• Acromegaly

• Diabetes

• Alcoholism

• Hypothyroidism

• Kidney failure and dialysis

• Pregnancy

• Infections

• Obesity

• Rheumatoid arthritis, systemic lupus erythematosus (SLE), and slceroderma

OCUPATIONAL DISEASE

• on a more probably than not basis (greater than 50%) that the workplace activities (exposure) in an individual case contributed to the development or worsening of the condition (outcome).

Summary

Dx;臨床徵狀及神經傳導檢查皆符合腕隧道症候群的診斷認定基準

Exposure:過往至今的工作 (repeated and forceful works),皆明顯地增加罹患腕隧道症候群的機會

Time sequence: 1980起工作 30年 , 於 2008 年開始出現雙手腕酸痛 , 無力和麻的情形 , 合乎危害暴露在前 , 發病在後之時序性。

可合理地排除其他非職業因素造成之腕隧道症候群之可能。

Thus, 此疾病由職業引起之可能性大於 50﹪。

診斷基準

勞工保險職業病種類表之 3.4 壓迫造成之神經麻痺：包括職業性腕道症候群等。

診斷： work related carpal tunnel syndrome, bilateral (雙側職業性腕隧道症候群 )

後續處理個案因經濟上之需求 , 目前仍需持續地工作 .

1.衛教2.職能治療3.藥物4.手術

Education

1. Avoid sleeping on wrists.

2. Hot and cold compresses

3. Take frequent breaks when typing and always stop if tingling or pain.

4. Avoid or reduce the number of repetitive wrist movements whenever possible.

Occupational Therapy

1. Wearing a neutral position wrist splint at night

2. Wearing a splint intermittently during work

3. Ergonomic aids, such as split keyboards, keyboard drawers, cushioned mouse pads, and wrist braces.

4. Job modification

5. Forearm/wrist stretching home exercise

6. Referral to an occupational therapist

MEDICATIONS

• Cyclo-oxygenase (COX) inhibitors

1.Nonselective : ibuprofen or naproxen.

2.COX-2 selective: celecoxib

• Local steroid injections into the carpal tunnel for short term relief.

Prognosis

• Symptoms often improve with treatment,

• but more than 50% of cases eventually require surgery.

• Surgery is often successful, but full healing can take months

SURGERY

• Carpal tunnel release

1. Release of the transverse carpal ligament

2. Open or endoscopic approach

3. Decompression of the median nerve at the wrist

• Revision after 6 months if worsening

Possible Complications

• If untreated, the nerve can be damaged, causing permanent weakness, numbness, and tingling.

The END