INTRODUCTION:

Carpal Tunnel Syndrome (CTS) is the utmost common compressive central mono-neuropathy seen in medical practice. Clinical symptoms comprise of numbness, tingling, burning, and/or pain associated with local compression of the median nerve at the wrist, subsequently resulting in mechanical compression or local ischemia^1-6. The median nerve controls sensations to the palm side of the thumb and fingers (except for the little finger), along with impulses to some muscles in the hand that move the thumb and fingers. The carpal tunnel-a fine passageway of ligament and bones at the base of the wrist-contains the median nerve and tendons. Several factors can cause CTS, including the anatomy of wrist, certain health problems and congestion of hand. Proper treatment typically can relieve the symptoms and reestablish normal function of the hand⁷.

BACKGROUND:

Carpal Tunnel Syndrome, initially studied by Paget in 1954, CTS is a common entrapment neuropathy, disturbing about 3.8% of the population^8-9. An entrapment neuropathy is a type of neuropathy caused due to pressure inside anatomical structures that are not stretchy.

Sustained or high pressure in the carpal tunnel obstructs microcirculation in the median nerve, leading to decreased action potentials, demyelination in the nerve and axonal degeneration. CTS is outlined as a symptomatic compression pathology of the median nerve in the wrist¹⁰.

ANATOMY:

Median nerve is formed by the unification of the lateral and medial roots which initiate from the lateral and medial cord of the brachial plexus, respectively (on the anterior surface of the axillary artery). It runs down the anteromedial part of the arm in the medial bicipital groove first lateral to the brachial artery, then in the middle of the upper arm the median nerve crosses the artery in anterior and lies on its medial side. Then it passes over the cubital fossa, deep to the bicipital aponeurosis and medial to the brachial artery.

Figure 1 Anatomy of Carpal Tunnel¹¹

Figure 2 Physiology of Carpal Tunnel Syndrome¹²

In the cubital fossa it gives rise to the anterior interosseous nerve, which descends on the interosseous membrane between the flexor digitorum profundus and flexor pollicis longus, and then passes behind the pronator quadratus supplying these three muscles. In the lower third of the forearm median nerve is located superficially, covered only by the fascia and moderately by the tendon of the palmaris longus muscle.

Then median nerve go in the palm of the hand through the carpal tunnel deep to the flexor retinaculum. In the palm of the hand median nerve gives off a muscular branches to the thenar muscles and to the lateral two lumbricals, then terminates by dividing into three common palmar digital nerves, which then divide into the palmar digital branches innervating the skin of the cross side of the palm, and the palmar side of the index finger, middle finger, and one-half of the ring finger.

There are numerous anatomic variations in the branching pattern of the median nerve in the forearm and hand, and its communications with several nerves^13-23. Poisel examined the hands of 100 cadavers and devised a classification system for median nerve variations and the relationship of the branches to the transverse carpal ligament. He defined the following three types: extra ligamentous (type I), subligamentous (type II), and transligamentous (type III). Lanz recorded a detailed anatomical study of the course of the median nerve in 246 hands during various surgical explorations. The variations can be classified into four types:

type 1. Variations of the course of the single thenar branch;

type 2. accessory branches at the distal carpal tunnel;

type 3. high division of the median nerve;

type 4. accessory branches proximal to the carpal tunnel.

EPIDEMIOLOGY AND SOCIOECONOMIC EFFECTS:

One of every five subjects generally reports pain, numbness and tingling sensation in the palm. A clinical examination and electrophysiology testing may confirm the existence of this form of neuropathy. Yearly incidence rates of 276:100,000 have been reported. CTS is more predominant in females than in males, with a frequency of 9.2% in females and 6% in men. The average age is 40 to 60 years. In Europe, 60% of work-related disorders were attributed to CTS. Some activities like fish processing are associated with an approximately 73% rate of incidence of CTS among the employees. Diabetic patients have a prevalence rate of 14% and 30% without and with diabetic neuropathy, respectively, whereas the prevalence of CTS during pregnancy has been reported to be around 2%. The UK demonstrates the highest number of CTS cases (7-19%), whereas in the US, the prevalence is 5%²⁴. The median number of leaves due to CTS is the highest in UK, at 27 days. In the US in 1995, nearly 400,000–500,000 CTS patients underwent surgery, which incurred an economic cost of $2 billion. This imposes a severe burden on the National Health Service.

SECONDORY CTS:

Many factors such as irregularities of the flexor tendons, synovium, and lesions may raise the pressure inside the carpal tunnel and lead to median nerve compression. Some diseases like diabetes, rheumatoid arthritis, tuberculosis, purulent tenosynovitis, systematic lupus erythematosus, gout or hyperthyroidism may influence the synovium²⁵.

DIABETES:

Diabetic patients may be at high risk of developing CTS. It has been reported to occur in 14% of DM patients without diabetic neuropathies and in up to 30% of the patients with diabetic neuropathies²⁶. The prevalence of CTR in patients with Type-2 diabetes has been projected to be about 4-14 fold higher than in normal individuals²⁷.

PREGNANCY:

Pregnancy and labor could cause peripheral nerve disorders, like CTS, facial nerve palsy, lumbosacral radiculopathy, and femoral neuropathy, of which CTS is that the most often rumored. CTS may occur due to edema associated with fluid retention within the synovium membrane, that exerts pressure on the median nerve.

SIGNS AND SYMPTOMS:

The symptoms of CTS can range from mild to devastating and usually progress progressively over weeks and months, or sometimes years. Initially they appears and go, but over time they may become constant. In the early stages of CTS, the patient usually reports pain, numbness, tingling, burning, or some combination of symptoms on the palm side of the thumb, index, middle, and ring fingers (but not the little finger). Such sensations might travel up to the forearm or shoulder.

Figure 3 Symptoms of Carpal Tunnel Syndrome¹¹

Symptoms may occur at any time. Because many people sleep with flexed wrists, symptoms at night are common and may awaken from sleep. During the day, symptoms typically occur when holding something, like a handwheel, phone or newspaper. Moving or shaking the hands typically relieve symptoms. Over time, the hand may become numb, and patients may lose the flexibility to feel and may experience sense of weakness within the hand and a tendency to drop objects. If the condition is extremely severe, muscles at the bottom of the thumb begin to atrophy.

CAUSES AND RISK FACTORS:

In normally, CTS develops when the tissues around the median nerve irritate or compress on the nerve along its course through the carpal tunnel. For instance, a wrist fracture or swelling of tissue resulting from arthritis or tendonitis can narrow the carpal tunnel and irritate to the nerve. In many cases, no single cause can be recognized and a combination of risk factors contributes to the development of the CTS. In all probability this condition is possessing to a congenital predisposition - the carpal tunnel is narrower in some people than in others²⁸. For this reason CTS is also more common in women. Other contributing factors include:

· Injury to the wrist (fracture or dislocation), a cyst or neoplasm within the carpal tunnel compressing on the nerve

· Inflammation will have an effect on the tendons or bursa within the carpal tunnel, exerting pressure on median nerve

· Disorders that directly affect the nerves and make them more susceptible to compression diabetes, overactivity of the pituitary gland, hypothyroidism, alcoholism. CTS is the most common complication of dialysis-related amyloidosis (DRA) developing in patients on long-term dialysis therapy

· Fluid retention (during pregnancy or menopause) may increase the pressure within carpal tunnel, irritating the median nerve

· Workplace factors like repeated use of vibrating hand tools or working on an assembly line that requires prolonged or repetitive flexing of the wrist²⁹

DIAGNOSIS OF CTS:

Doctors can produce the symptoms of CTS by using specific tests. The two most broadly used diagnostic and provocative tests used to detect CTS are Phalen’s test and Tinel’s tests. A pain or paraesthesia in the median nerve, on extending the wrist and maintaining this position for 1 minute, is indicative of positive sign of CTS. Phalen’s test has a sensitivity range of 67% to 83%, although its specificity ranges from 40% to 98%. Tinel’s test is performed by tapping on the volar surface of the wrist and, if positive, it causes paraesthesia in median nerve-innervated fingers such as thumb, index and middle finger, and the radial side of the ring finger. The sensitivity range of Tinel’s test is vary from 48% to 73% and specificity is 30% to 94%. The prognostic and diagnostic value of these tests has been uncertain; hence, their use is often coupled with assessment of the patient’s clinical history and other methods of diagnosis such as nerve conduction study (NCS)³⁰.

Nerve Conduction Studies (NCS):

NCS offers valuable information about the physiological condition of the median nerve across the carpal tunnel. In NCS, a transcutaneous pulse of electricity, which triggers an action potential in the nerve, excites the nerve. A proximally or distally placed recording electrode detects the wave of depolarization as it passes by the surface electrode. The amplitude of the median nerve segment across the carpal tunnel is associated to a different nerve segment that does not traverse the carpal tunnel, such as the radial or ulnar nerve³¹.

Magnetic Resonance Imaging (MRI):

The diagnosis of CTS is usually based on the symptoms, clinical history and NCS. Though, many patients present a normal NCS, which necessitates the use of ultrasound and MRI. MRI is very useful for evaluating the infrequent pathological causes of CTS such as bone deformities, ganglion, hemangioma, which could influence surgical interventions. MRI incorporates a sensitivity range of 96%, whereas the specificity is as low as 33-38%. MRI provides anatomical data instead of details regarding the nerve dysfunction. Although it is an expensive technique, it’s still preferred by many patients. It is often used to evaluate the point of entrapment post failure of Carpel Tunnel Release (CTR) surgery²⁵.

Ultrasonography:

The importance of ultrasound (US) assessment as a diagnostic tool in analysis of CTS is related to the fact that it can effectively measure thickening of the median nerve, flattening of the nerve among the tunnel and bowing of the flexor retinaculum (FR)²⁴.

TREATMENT:

The treatment options for CTS are classified into two types: conservative and surgical.

CONSERVATIVE TREATMENT:

Conventional treatment is usually provided to patients with mild to moderate symptoms. These options include corticosteroids, oral and transvenous steroids, vitamins B6 and B12, nonsteroidal anti-inflammatory drugs (NSAIDs), yoga, carpal bone mobilization and the use of hand splints. It has been confirmed that patients benefited considerable with conservative treatment, even though, in the short term, while their long term advantages are still a matter of debate. Other conservative treatment methods such as splinting, exercise, chiropractic treatment or magnetic therapy has not shown any significant symptomatic recovery relative to controls.

Steroid Administration:

Administration of steroids as a treatment modality for CTS has been a subject matter of discussion. While one study showed that steroidal injection produced significant clinical enhancement in symptoms one month after the injection, another experiment showed no such difference beyond one month³². Although corticosteroid treatment is effective in ameliorating such symptoms as edema and inflammation, it is accompanied by side effects such as reduction of mechanical strength of the tendon, triggering further degradation³³. Some authors have reported that NSAID’s, pyridoxine and diuretics are no longer efficacious in comparison to a placebo in relieving the signs of CTS³⁴.

Local Injection:

A combination of local injection in the wrist and a local anesthetic into the carpal tunnel are often used in CTS patients with delicate to moderate symptoms. Recent reviews have studied the impact of local corticosteroid injections and demonstrated that this kind of treatment lends a far larger recovery rate at one month compared to the placebo. Local corticosteroid injection for carpal tunnel syndrome provides larger clinical improvement in symptoms at one month after injection compared to placebo. Significant symptom relief on the far side one month has not been demonstrated. Also it has been proven that two or more local corticosteroid injections do not provide significant added clinical benefit compared to one injection³⁵.

Splinting:

Wearing a splint at a neutral angle aids in decreasing the repetitive flexion and eases the swelling within the soft tissue and tenosynovitis. The fundamental premise for wrist splinting is the assumption that CTS symptoms worsen with activity and improve with rest. Once applied within 3 months of onset of the disease, splinting has been proven to be an efficacious treatment choice. Splinting provided symptomatic relief and improved sensory and motor nerve conduction velocities at long-term follow-up when the splints were worn almost every night^36-37.

SURGERY:

Surgery for CTS involves carpal tunnel release (CTR), during which the transverse carpal ligament (TCL) is cut to create more space in the carpal tunnel and reduce the pressure. Long-term beneficial outcomes following CTR are seen in just about 70–90% of the patients¹⁰. CTR is a suitable option for diabetic patients with CTS and peripheral neuropathy. In the most recent literature, surgery has been tried to be much better treatment strategy for CTS as compared to splinting and alternative conservative treatment choices³⁸. There are several sorts of CTR based on the surgical techniques used: conventional open carpal tunnel release (OCTR), mini-OCTR, and endoscopic carpal tunnel release (ECTR).

Figure 4 OCTR³⁹

Figure 5 ECTR³⁹

Endoscopic Carpal Tunnel Release (ECTR) is conducted as either a single portal surgery⁴⁰ or a dual portal technique⁴¹. ECTR could be a lot of helpful technique in accomplishing decompression of the median nerve. However, its potency relative to the less invasive OCTR for recovery from CTS post-surgery is still a matter of debate. The advantage of ECTR over OCTR is that by partitioning the TCL from inside. The skin and muscle on top are preserved, probably reducing post-surgery morbidity, expediting recovery and return to work, and maintaining grip strength. The risk of any major injuries to nerves, vessels, or tendons was shown to be lower in an ECTR group (0.19%) relative to a OCTR group (0.49%). OCTR has been shown to cause complications such as hypertrophic scar, infection and scar tenderness, which is lesser in ECTR. ECTR conjointly shows quicker recovery in patients undergoing the surgery within the initial 2 weeks, with faster relief from pain and faster improvement in functional activities. However, at 1 year, both ECTR and OCTR appear to be evenly efficient.

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

REFERENCES:

1. Aroori S, Spence RA. Carpal Tunnel Syndrome. The Ulster Medical Journal. 2008;77:6-17.

2. Cranford CS, Ho JY, Kalainov DM, Hartigan BJ. Carpal tunnel syndrome. J Am Acad Orthop Surg. 2007;15:537-48.

3. Mackinnon SE, Dellon AL. Surgery of the peripheral nerve. New York: Thieme Medical Publishers. 1988:146-69.

4. Ghasemi-Rad M, Nosair E, Vegh A, Mohammadi A, Akkad A, Lesha E. A handy review of carpal tunnel syndrome: From anatomy to diagnosis and treatment. World Journal of Radiology. 2014;6(6):284-300.

5. Kasundra GM, Sood I, Bhargava AN, Bhushan B, Rana K, Jangid H, et al. Carpal tunnel syndrome: Analyzing efficacy and utility of clinical tests and various diagnostic modalities. Journal of Neurosciences in Rural Practice. 2015;6:504-10.

6. Ali Z, Khan A, Shah SMA, Zafar A. Clinical and electro-diagnostic quantification of the severity of carpal tunnel syndrome. Ann Pak Inst Med Sci. 2012;8(4): 207-12.

7. Mizia E, Iskra T, Musiał A, Matuszyk A, Tomaszewski KA. Carpal tunnel syndrome—anatomical and clinical correlations. Folia Medica Cracoviensia. 2013.

8. Alfonso C, Jann S, Massa R, Torreggiani A. Diagnosis, treatment and follow-up of the carpal tunnel syndrome: a review. Neurological Sciences. 2010;31(3):243–52.

9. Atroshi I, Gummesson C, Johnsson R, Ornstein E, Ranstam J, Rosén I. Prevalence of carpal tunnel syndrome in a general population. JAMA. 1999;282(2):153–8.

10. Ibrahim I. carpal tunnel syndrome: A review of the recent literature. The Open Orthopaedics Journal. 2012;6(1):69–76.

11. Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". Wiki Journal of Medicine.1(2). DOI:10.15347/wjm/ 2014.010. ISSN 2002-4436.

12. Rodner C, Raissis A, Akelman E: Carpal tunnel syndrome. Orthopaedic Knowledge Online Journal. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2009; 7(5). Accessed March 2016

13. Poisel S. ursprung und Verlauf des Ramus muscularis des Nervus digitalis palmaris communis I (N. medianus). Chir Praxis. 1974; 18: 471–474.

14. Lanz U. Anatomical variations of the median nerve in the carpal tunnel. The Journal of Hand Surgery. 1977; 2(1): 44–53.

15. Barbe M, Bradfield J, Donathan M, Elmaleh J. Coexistence of multiple anomalies in the carpal tunnel. Clinical Anatomy: The Official Journal of the American Association of Clinical Anatomists and the British Association of Clinical Anatomists. 2005; 18: 251–259.

16. Tountas CP, Bhrle DM, Mac Donald CJ, Bergman RA. Variations of the median nerve in the carpal. The Journal of Hand Surgery. 1987; 12: 708–712.

17. Hurwitz PJ. Variation in the course of the thenar motor branch of the median nerve. The Journal of Hand Surgery. 1996; 21B: 344–346.

18. Kozin SH. The anatomy of the recurrent branch of the median nerve. The Journal of Hand Surgery. 1998; 23A: 852–858.

19. Cavallo AV, Slattery PG, Barton RJ. Endoscopic carpal tunnel release and congenital anomalies of the median nerve. Hand Surgery. 2003; 8(2): 265–270.

20. Mizia E, Klimek-Piotrowska W, Walocha J, Rutowski R, Wojtala R. The median nerve in the carpal tunnel. Folia Morphologica. 2011; 70(1): 41–46.

21. Mizia E, Gziut T, Kruk S, Golec E, Walocha J. Anomalous course of thenar motor branch of the median nerve — a case report. Kwart Ortopaedics. 2012; 2: 270–273.

22. Mizia E, Tomaszewski KA, Goncerz G, Depukat P, Walocha J. The importance of ulnar side approach in carpal tunnel syndrome surgical treatment — anatomic variations of the median nerve and surrounding structures. J Orthop Trauma Surg Rel Res. 2012; 4: 19–24.

23. Mizia E, Tomaszewski KA, Goncerz G, Kurzydło W, Walocha J. Median nerve thenar motor branch anatomical variations. Folia Morphologica. 2012; 71(3): 183–186.

24. Zamborsky R, Kokavec M, Simko L, Bohac M. Carpal tunnel syndrome: symptoms, causes and treatment options. Literature review. Ortop Traumatol Rehabil. 2017 Jan 26;19(1):1-8.

25. Uchiyama S, Itsubo T, Nakamura K, Kato H, Yasutomi T, Momose T. Current concepts of carpal tunnel syndrome: pathophysiology, treatment, and evaluation. Journal of Orthopaedic Science. 2010;15(1):1–13.

26. Perkins BA, Olaleye D, Bril V. Carpal tunnel syndrome in patients with diabetic polyneuropathy. Diabetes Care. 2002;25(3): 565–9.

27. Makepeace A, Davis WA, Bruce DG, Davis TME. Incidence and determinants of carpal tunnel decompression surgery in type 2 diabetes: the Fremantle Diabetes Study. Diabetes Care. 2008;31(3):498–500.

28. Hakim AJ, Cherkas L, El Zayat S, MacGregor AJ, Spector TD. The genetic contribution to carpal tunnel syndrome in women: a twin study. Arthritis Care and Research. 2002; 47: 275–279.

29. Kopeć J, Gadek A, Drożdż M, Miśkowiec K, Dutka J, Sydor A, Chowaniec E, Sułowicz W. Carpal tunnel syndrome in hemodialysis patients as a dialysis-related amyloidosis manifestation-incidence, risk factors and results of surgical treatment. Medical science monitor: international medical journal of experimental and clinical research. 2011; 17(9): CR505–509.

30. De Krom MC, Knipschild PG, Kester AD, Spaans F. Efficacy of provocative tests for diagnosis of carpal tunnel syndrome. The Lancet. 1990;335(8686):393–5.

31. Werner RA, Andary M. Carpal tunnel syndrome: pathophysiology and clinical neurophysiology. Clinical Neurophysiology. 2002; 113(9):1373–81.

32. Marshall SC, Tardif G, Ashworth NL. Local corticosteroid injection for carpal tunnel syndrome. In The Cochrane Collaboration, editor. Cochrane Database of Systematic Reviews. Chichester, UK: John Wiley and Sons, Ltd; 2007.

33. Wong MWN, Tang YN, Fu SC, Lee KM, Chan KM. Triamcinolone suppresses human tenocyte cellular activity and collagen synthesis. Clinical Orthopaedics and Related Research®. 2004;(421):277–81.

34. Gerritsen AAM, De Krom MCTFM, Struijs MA, Scholten RJPM, De Vet HCW, Bouter LM. Conservative treatment options for carpal tunnel syndrome: a systematic review of randomised controlled trials. Journal of Neurology. 2002;249(3):272–80.

35. Stark H, Amirfeyz R. Cochrane corner: local corticosteroid injection for carpal tunnel syndrome. Journal of Hand Surgery (European Volume). 2013;38(8):911–4.

36. Sevim S, Dogu O, Camdeviren H, et al. Long-term effectiveness of steroid injections and splinting in mild and moderate carpal tunnel syndrome. Neurological Sciences. 2004;25(2):48–52.

37. Kruger VL, Kraft GH, Deitz JC, Ameis A, Polissar L. Carpal tunnel syndrome: objective measures and splint use. Archives of physical medicine and rehabilitation.1991;72(7):517–20.

38. Kim PT, Lee HJ, Kim TG, Jeon I-H. Current approaches for carpal tunnel syndrome. Clinics in Orthopedic Surgery. 2014;6(3):253–7.

39. Johns Hopkins Medicine. Treatments, Tests and Therapies. Carpal Tunnel Release. Available from: URL: https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/carpal-tunnel-release

40. Zuo D, Zhou Z, Wang H, et al. Endoscopic versus open carpal tunnel release for idiopathic carpal tunnel syndrome: a meta-analysis of randomized controlled trials. Journal of Orthopaedic Surgery and Research. 2015;10(1):12.

41. Chow JC. Endoscopic release of the carpal ligament: A new technique for carpal tunnel syndrome. Arthroscopy: The Journal of Arthroscopic and Related Surgery. 1989;5(1):19–24.

Received on 20.12.2019 Modified on 04.02.2020

Research J. Pharm. and Tech. 2020; 13(10):4961-4965.

DOI: 10.5958/0974-360X.2020.00870.7