Carpal tunnel syndrome

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Mohammadmain Rezazadehsaatlou [2]

Carpal tunnel syndrome (CTS) or Median Neuropathy at the Wrist is a medical condition in which the median nerve is compressed at the wrist, leading to pain, paresthesias, and muscle weakness in the forearm and hand.[1] A form of compressive neuropathy, CTS is more common in women than it is in men, and, though it can occur at any age, has a peak incidence around age 42.[2] The lifetime risk for CTS is around 10% of the adult population.[3].

Most cases of CTS are idiopathic, without known cause. Repetitive activities are often blamed for the development of CTS, along with several other possible causes. However, the correlation is often unclear.

It is a multi-faceted problem and can therefore be challenging to treat. Still, there is a multitude of possible treatments, e.g. treating any possible underlying disease or condition, immobilizing braces, physiotherapy, medication, prioritizing hand activities and ergonomics. Ultimately, carpal tunnel release surgery may be required. Outcomes are generally good. The condition was first noted in the medical literature in the early 1900s.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Mohammadmain Rezazadehsaatlou [2]

Carpal tunnel syndrome (CTS) is the most common and a well–recognized mononeuropathy in medicine. Historical evaluations showed that it took more than 100 years from the initial reports and observations to describe the pathophysiology of this problem as a median nerve compression of wrist.

According to the available pieces of evidences about the Carpal tunnel syndrome (CTS) are interesting. The first description of median nerve illness in the carpal tunnel originates from 1854 and almost 100 years later this problem with its specific sign and symptoms called Carpal tunnel syndrome (CTS). Prior to this event, patients having these sign and symptoms were diagnosed as having acroparaesthesia or even the motor branch of the median nerve compression or the brachial plexus compression. Meanwhile, the “acroparesthesia” was used to describe a chronic and early morning and nocturnal paresthesias, numbness, pain, and weakness in hand with a slight decrease of sensibility of fingers; which was more common in female population. Nowadays, we can call this condition as Carpal tunnel syndrome (CTS). Here we can find the historical perspective of CTS in clinical practice ^{[1][2][3][4][5][6][7][8][9]}:

In 1854, Paget J had the first clinical description of CTS in his two cases diagnosed with the median nerve compression within the carpal tunnel: one case was post-traumatic and another one was idiopathic

In 1880, Putnam JJ had reported the first case series of 37 patients which most of them were female with the age of 35 years old, suffering from the same problems: “the subjective sensibility impairment of the skin (which nowadays we call it as “numbness”), with repeatedly occurrence at nights or very early in the mornings and in some cases it’s been reported that shaking bit or hang out of the bed would decrease the symptoms. Which we can conclude that these previously mentioned symptoms nowadays are considered as symptoms of CTS.

In 1893, Friedrich Schultze confirmed the Putnam’s sensory findings about the median nerve compression. and he “Schultz” used the word acroparesthesia” for the sensory symptoms description .

In 1895, considering the recent discoveries of X-rays, Doctors had this opportunity to observe both motor and sensory conversions of the hand among their patients.

In 1909, Hunt have published a series of reports about the thenar muscle atrophy as a disease process different than the sensory findings reported by Putnam (in 1880). Hunt with total exclusion of sensory pathology had been emphased on motor pathology caused by median nerve compression.

In 1913, Marie and Foix published an article entitled “Atrophie isolée de l’éminence thenar d’origine névritique: rôle du ligament annulaire antérieur du carpe dans la pathogénie de la lésion”, which was an anatomopathological descriptions of the structural conversion affecting the median nerve due to the  carpal tunnel compression.

In 1914, Hunt JR, described the pathological evaluation of the thenar eminence atrophy. Which in his opinion it happened due to the motor branch compression of the median nerve within the carpal tunnel.

In 1988, Pfeffer GB hypothesised that the cervical rib is responsible for the compression of the brachial plexus at the level of thoracic outlet. And because of this conclusion the cervical rib removal was considered as the main therapy for CTS during the first 40 years of the 20th century.

In 1922, Lewis D, Miller EM reported the possible role of fracture of the distal epiphysis of the radius on chronic compression of the median nerve.

In 1924 Galloway described the surgical method of the carpal tunnel treatment “…marked wasting of the thenar eminence and trophic changes in the nails of the index finger and thumb… an exploration from the flexor crease at the wrist downward for an inch and upward for 2 inches was performed…immediately following the operation, sensation in the index finger improved”

In 1929, Watson JR reported the possible role of arthritic deformities of the carpal bones on chronic compression of the median nerve.

In 1933, Abbott LC, Saunders M reported the possible role of dislocation of the carpus on chronic compression of the median nerve.

In 1933, Learmonth JR perforemd the first surgery to open the carpal tunnel in a post-traumatic case suffering from the compression of the median nerve.

In 1938, Moersch published described the median nerve compression within the carpal tunnel without previous history of trauma.

In 1992, Amadio PC Mayo Clinic, published a letter by Galloway dated 1924.

In 1946, Cannon BW, Love JG performed and described of a surgery of idiopathic CTS.

In 1947, Russell Brain described acroparesthesia and neuritis of thenar area as a result of median neuropathy due to the flexor retinaculum compression.

In 1947, Brain, Wright, and Wilkinson described idiopathic CTS from both clinical and anatomopathological aspects.

In 1949, McArdle described the possible relationship between acroparesthesias and median nerve compression within the carpal tunnel.

In 1950 – 1966 Phalen GS worked on the pathophysiology of idiopathic CTS.

In 1953, Gilliatt and Wilson described the tourniquet test for diagnosis of CTS.

In 1950s CTS reached its final characterization.

In 1960, CTS became an easily diagnosed disease with well defined treatment options. It was known as the most frequent peripheral entrapment neuropathy with an incidence of 99 cases per 100,000 population.

In 1989, Chow JC described the endoscopic intervention method of CTS

In 1988, Le Loet X concluded that the CTS was the most comon nerve compression syndrome.

In 1996, Kerwin described different underlying causes of CTS. He concluded that increasing the carpal tunnel volume (for example due to the inflammation, edema, and tumor) would increase pressure within the canal, causing the mechanical changes or even ischemia of the median nerve.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Mohammadmain Rezazadehsaatlou [2]

Carpal tunnel syndrome (CTS) CTS is the most frequent neuropathy of upper extremities and also it is known as the common work-related musculoskeletal disorder. CTS found in approximately 3% to 6% of adults in the United States.According to the clinical practice guideline (CPG) from the American Academy of Orthopedic Surgeons (AAOS), Carpal tunnel syndrome (CTS) is “a symptomatic neuropathy compression of the median nerve within wrist, characterized by increased pressure within the carpal tunnel in additon to the decreased function of the nerve.”

It is the most common compressive neuropathy affecting the upper extremity, present in approximately 3% to 6% of adults in the United States.

Clinical diagnosis of CTS has been based on patients symptoms and meanwhile electrodiagnostic evaluation used for confirmation in this regard. The electrodiagnostic is known as the gold standard for CTS final diagnosis.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Mohammadmain Rezazadehsaatlou [2] Dheeraj Makkar, M.D.[2]

Carpal tunnel syndrome (CTS) is known as a common pathology in hand. Most common diagnosis of CTS is idiopathic but it is accepted that the median nerve neuropathy could be caused due to the chronic increased pressure within the carpal tunnel.

But the exact pathophysiology of this pressure increase is not well known yet. CTS usually occurs due to the mechanical compression and/or local ischemia.

CTS is diagnosed based on symptoms such as numbness, tingling and/or burning in the distribution of the median nerve in the hand. However, the symptoms are frequently documented outside the distribution of the median nerve as well. The CTS has a complex pathophysiology and it happens due to the interactions of many mechanisms.

Pathophysiology

• increased pressure on the median nerve affects intraneural blood supply

normal carpal tunnel pressure measures from 2.5mmHg at rest with the wrist in neutral to 30mmHg with wrist flexion at 20mmHg intraneural venous flow is impeded and edema occurs.

• Complete disruption of arteriolar flow occurring at 60-80mmHg
  • in patients with CTS, carpal tunnel pressures range from 30-110mmHg

mechanism

• exposure to repetitive vibratory exposure (e.g., typing on a keyboard)
• certain athletic activities
  • cycling
  • tennis
  • throwing
  • trauma ( distal radius fractures, carpal bone fractures/dislocations)

Patho-anatomy most common causes of nerve compression pathologic (inflamed) synovium – most common cause of idiopathic CTS repetitive motions in a patient with normal anatomy space occupying lesions

Normal pressure of carpal tunnel is ranged from 2 to 10 mm Hg. The carpal tunnel is a anatomic space surrounded by the carpal bones on the medial, dorsal, and lateral sides and the the flexor retinaculum located on the palmar side and nine flexor tendons and the median nerve are concealed by the subsynovial connective tissue (SSCT). It is clear that the CTS is a chronic peripheral nerve compression neuropathy, but its pathophysiology are less clear. Various studies have confirmed that the increased canal pressure can be found in patients with CTS; this elevation is correlated with clinical signs in patients. For example tenosynovitis or synovial fibrosis, are known as the potential cause of elevation in carpal tunnel pressure. Another proposed mechanism is canal stenosis. Pathological changes of ligaments surrounding nerves such as changes in the connective tissue density and/or its flexibility are believed to be the main cause of this pressure elevation. Experimental studies raveled that there is a relationship between the duration, and amount of carpal tunnel with the median nerve dysfunction. Meanwhile, the higher carpal tunnel pressure leads to the ischemic compression of the median nerve.

Hypertrophy of the synovial tissue of the flexor tendons cis another cause of increased carpal tunnel pressure and consequently leading to the CTS occurrence and progression. Meanwhile, its been reported that the increased expression of prostaglandin E2 and/or VEGF and tenosynovitis are the important risk factors to the development of symptomatic and idiopathic CTS, respectively. Then, the constrictive scar tissue around the median nerve leads to the tethering of the median nerve. Also, the synovial tissue increases the volume of tissue ( the most common area in this regard are: the entrance and exit regions of the canal) by the inflammatory thickening which finally leads to the increased pressure within the carpal tunnel.

It’s been found that in neuropathic disorders the nerves at the site of compression are narrowed and they’ve been enlarged at the proximal and distal segments. This compression cause the Demyelination of the nerve which can spread to the whole internodal segment which consequently interrupts the leaving the axonal function. The persisted compression interrupts the bloodflow to the endoneural capillary system changes the blood-nerve barrier, and leads to the endoneural edema. The edema causes the nerve swelling, which affects the movement of the nerve within the anatomical compartment.

Ischemic vascular injuries are also known as the essential factors in CTS. An increase pressure within the tunnel could cause a vasculature breakdown which leads to the inflammatory cells and proteins accumulation. Also, the biochemical disturbances of microvascular structure of the nerve leads to a reduction in the endoneurial blood flow and also the oxygen tension. On the other hand, the local compression could change the intraneural circulatory and leads to the higher permeability of endoneurial vessels which leads to the edema of the endoneurial space; . the edema affects the diffusion distance for oxygen from the capillaries, which leads to hypoxia.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Carpal tunnel syndrome is the most common entrapment neuropathy, affecting 2-10% of adults in the general population. The underlying cause of CTS is not well known yet but trauma, repetitive maneuvers, certain diseases, and even pregnancy are known to be causes in this regard. In most cases the CTS is found idiopathic. Meanwhile .

The international debate regarding the relationship between CTS and repetitive motion and work is ongoing. The Occupational Safety and Health Administration (OSHA) has adopted rules and regulations regarding cumulative trauma disorders. Occupational risk factors of repetitive tasks, force, posture, and vibration have been cited. However, the American Society for Surgery of the Hand has issued a statement that the current literature does not support a causal relationship between specific work activities and the development of diseases such as CTS.

The relationship between work and CTS is controversial; in many locations workers injured at work are entitled to time off and compensation. Many cases of carpal tunnel syndrome are provoked by repetitive grasping and manipulating activities, and the exposure can be cumulative. Symptoms are commonly exacerbated by forceful and repetitive use of the hand and wrists in industrial occupations. Carpal tunnel syndrome results in billions of dollars of workers compensation claims every year.

Studies done by the National Institute for Occupational Safety and Health (NIOSH), indicated that job tasks involving highly repetitive manual acts or necessitating wrist bending or other stressful wrist postures were connected with incidents of CTS or related problems. However, it appears that the 30+ studies reviewed were concerned with the occupations of assembly line workers, meat packers, food processors, and the like, not general office work.

In addition, a 2005 study found that people who have discomfort at the base of the neck or in the shoulder or work with their shoulder in elevation (indicators of poor working postures) are more likely to develop a repetitive overuse injury. These factors can affect the biomechanics of the upper limb or tissue tolerance to repetitive tasks resulting in injury, or both. Postural and spinal assessment along with ergonomic assessments should be included in the overall determination of the condition. Addressing these factors have been found to improve the status of work related upper limb injuries.

Hypothyroidism, osteoarthritis and diabetes were most often associated with CTS-like symptoms, as were variables such as age, obesity and wrist dimension. In a 1998 study, only 35 of 297 subjects were aware of the underlying health condition which could account for their CTS-like symptoms. Hence, these causes would be missed by doctors if they were relying on a patient’s health history to rule out other causative factors. It is important that a doctor rule out other causes of CTS-like symptoms. If a patient does not have CTS, corrective surgery is destined to fail.

Studies have also related carpal tunnel and other upper extremity complaints with psychological and social factors. A large amount of psychological distress showed doubled risk of the report of pain, while job demands, poor support from colleagues, and work dissatisfaction also showed an increase in the report of pain, even after short term exposure. A minority viewpoint holds that stress is the main cause, rather than a contributing factor, of a large fraction of pain symptoms usually attributed to carpal tunnel syndrome.

• Fractures of one of the arm bones, particularly a Colles’ fracture.
• Dislocation of one of the carpal bones of the wrist.
• Strong blunt trauma to the wrist or lower forearm, incurred for example by using arm extremity to cushion a fall or protecting oneself from falling heavy objects.
• Hematoma forming inside the wrist, because of internal hemorrhaging.
• Deformities due to abnormal healing of old bone fractures.

Misalignment between carpal bones should be the most common cause of CTS, because by adjusting these bones’ alignment, CTS dramatically decreases

Non-traumatic causes generally happen over a period of time, and are not triggered by one certain event. Many of these factors are manifestations of physiologic aging and should not be considered preventable. Examples include:

• Tenosynovitis, which is inflammation of the thin mucinous membrane around the tendons. Part of the process of inflammation is swelling, and this compresses the nerve. Swelling of this membrane is the final common pathway for most cases of carpal tunnel, whether caused idiopathically, through exposure, or medically.
• With pregnancy and hypothyroidism, fluid is retained in tissues, which swells the tenosynovium.
• Acromegaly, a disorder of growth hormones, compresses the nerve by the abnormal growth of bones around the hand and wrist.
• Tumors (usually begin), such as a ganglion or a lipoma, can protrude into the carpal tunnel, reducing the amount of space. This is exceedingly rare (less than 1%).

• Double crush syndrome, where there is compression or irritation of nerve branches contributing to the median nerve in the neck or anywhere above the wrist. This then increases the sensitivity of the nerve to compression in the wrist. This, while a possible factor, is also a rare contributor in most cases.

• Idiopathic causes are common.

• Common activities that have been identified as contributing to repetitive stress induced carpal tunnel syndrome include:
• Use of power tools
• Construction work such as handling many bricks, stone and/or lumber

Often people suffering from carpal tunnel syndrome can have multiple contributing factors which are aggravated by vigorous hand activities and repetitive stress trauma to the hand.

Proper attention to ergonomic considerations can reduce or eliminate these kinds of exposures.

While carpal tunnel syndrome is often called a “repetitive strain injury” (RSI) or “cumulative trauma disorder” (CTD), these labels are discouraged by physicians, particularly hand specialists. Carpal tunnel is a specific condition with specific symptoms that responds fairly reliably. Most of the time, carpal tunnel is not caused by a “strain” or “trauma” of any type. RSI and CTD are relatively non-specific terms with non-specific symptoms that respond variably to treatment.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

carpal tunnel syndrome is often associated with repetitive work-related motions. Since, there are many conditions cause similar symptoms to CTS, an accurate history and physical examination are essential in this regard.

• Idiopathic
• Carpometacarpal arthritis of thumb
• Cervical radiculopathy (C6)
• Flexor carpi radialis tenosynovitis
• Median nerve compression at elbow
• Raynaud phenomenon
• Ulnar or cubital tunnel syndrome
• Vibration white finger
• Volar radial ganglion
• Wrist degenerative arthritis
• Rheumatoid Arthritis
• Joint line pain, pain on motion, radiologic finding
• Neck pain, numbness in thumb and index finger only
• Tenderness near base of thumb
• Tenderness at the proximal forearm
• History of symptoms related to cold exposure
• First dorsal interosseous weakness, fourth and fifth digit paresthesias
• Uses vibrating hand tools at work
• Mass near base of thumb, above wrist flexion crease
• Limited motion at wrist, radiologic finding

• Acromegaly
• Amyloidosis
• Benign tumor
• Congestive Heart Failure
• Dermatomyositis
• Diabetes Mellitus
• Estrogens
• Fibrosis of flexor tendons
• Gout
• Hematoma
• Hypothyroidism
• Leprosy
• Mucopolysaccharidoses
• Paget’s Disease
• Paraproteinemia
• Pregnancy
• Sarcoidosis
• Scleroderma
• Systemic Lupus Erythematosus
• Tenosynovitis of flexor tendons
• Trauma
• Tuberculosis
• Uremia
• Wrist ganglion

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

CTS is the most common compressive neuropathy and the pathology involving the snovium is the most common cause of idiopathic CTS. CTS affects 5-10% of general population

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Dheeraj Makkar, M.D.[2] Associate Editor(s)-in-Chief: Joseph Nasr, M.D.[3]

The most important risk factors for developing carpal tunnel syndrome include: Anatomic factors, age, sex, inflammatory conditions, obesity, alterations in the balance of body fluids, other medical conditions

The most important risk factors for developing carpal tunnel syndrome include:

• Anatomic factors
  • Wrist fracture
  • Wrist dislocation
  • Wrthritis
  • People with smaller carpal tunnels may be more likely to have carpal tunnel syndrome.
• Age
  • Carpal tunnel syndrome (CTS) most commonly affects adults between 40 and 60 years of age, with peak prevalence typically reported in the mid-40s to mid-50s.
  • It is uncommon in children and young adults, except in cases with congenital anomalies, trauma, or systemic conditions (e.g., mucopolysaccharidoses).
  • Prevalence increases with age due to cumulative repetitive strain, degenerative wrist changes, and higher incidence of comorbidities such as diabetes, hypothyroidism, and arthritis.
  • CTS is more common in women, especially during perimenopausal years and in pregnancy, where hormonal and fluid balance changes contribute to median nerve compression.
• Sex 
  • Women, especially those taking birth control pills, going through menopause, or taking estrogen, have the highest risk of developing CTS
• Nerve-damaging conditions
  • Chronic illnesses such as diabetes
• Inflammatory conditions
  • Rheumatoid arthritis
• Obesity
• Alterations in the balance of body fluids
  • Pregnancy
  • Menopause
• Other medical conditions
  • Kidney failure
    • Hemodialysis:^[1][2][3][4]
      • Carpal tunnel syndrome is significantly more common in patients undergoing long-term hemodialysis.
      • Risk increases with dialysis duration and is strongly associated with dialysis-related β2-microglobulin amyloid deposition within the carpal tunnel.
      • Venous hypertension, subclinical access-related ischemia, and altered fluid dynamics from arteriovenous access may exacerbate median nerve compression.
      • Symptoms are typically limited to the median nerve distribution, worsen at night, and lack ischemic features, helping differentiate from access-related hand ischemia.
  • lupus
  • Hypothyroidism
  • Multiple sclerosis
• Workplace factors 
  • Working with vibrating tools
  • Assembly line
  • Computer use

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Dheeraj Makkar, M.D.[2]

Routine screening for CTS in the general population is not indicated. Instead, a targeted approach—using symptom questionnaires, physical exam maneuvers, and selective imaging or nerve conduction studies—is recommended for high-risk occupations and patients with systemic predispositions.

Carpal tunnel syndrome is primarily a clinical diagnosis, and there are no population-based screening programs recommended for asymptomatic individuals. Instead, screening is generally targeted toward high-risk groups and focused on early detection of symptomatic disease to prevent progression.

• At-Risk Populations:

Workers exposed to repetitive wrist motions, vibrating tools, or prolonged computer use.

Patients with systemic risk factors: diabetes, hypothyroidism, obesity, rheumatoid arthritis, pregnancy, or amyloidosis.

• Screening Tools:

Symptom questionnaires and diagrams: The self-administered hand diagram is highly specific (~76%) for CTS.

• Provocative maneuvers: Phalen’s test, Tinel’s sign, and the carpal tunnel compression test (Durkan’s) are used in outpatient or occupational health settings for early identification.

• Sensory testing: Semmes–Weinstein monofilament testing and two-point discrimination may detect early sensory deficits.

• Electrodiagnostic studies: Not suitable for general screening, but used to confirm diagnosis in equivocal or high-risk cases.

• Ultrasound: Increasingly used for screening in selected groups, as it can demonstrate median nerve enlargement and structural causes noninvasively.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Dheeraj Makkar, M.D.[2]

Recurrence of sign and symptoms after surgical or nonsurgical interventions is a possible fact. The most important complications include: Scar formation, nerve damage, vascular injuries, incomplete release of the ligament, wound infections.

hand overuse, particularly with vibrating equipment or frequent computer use

• Symptoms

numbness and tingling in radial 3-1/2 digits clumsiness pain and paresthesias that awaken patient at night

• Physical exam

inspection thenar atrophy Riche-Cannieu anastomosis connects the deep branch of the ulnar nerve to the recurrent motor branch of the median nerve, may have preserved thenar strength and severe CTS self administered hand diagram

• the most specific test (76%) for carpal tunnel syndrome

palpation occasionally tender to palpation over the carpal tunnel (rare)

• provocative tests
• carpal tunnel compression test (Durkan’s test)

is the most sensitive test to diagnose carpal tunnel syndrome performed by pressing thumbs over the carpal tunnel and holding pressure for 30 seconds. onset of pain or paresthesia in the median nerve distribution within 30 seconds is a positive result.

• Phalen test

wrist volar flexion against gravity for ~60 sec produces symptoms less sensitive than Durkan compression test

• Tinel’s test

provocative tests performed by tapping the median nerve over the volar carpal tunnel

• Semmes-Weinstein testing

most sensitive sensory test for detecting early carpal tunnel syndrome measures a single nerve fiber innervating a receptor or group of receptors

• Innervation density test

static and moving two-point discrimination A failure to discriminate two points held 5mm or less apart from one another is a positive test suggestive of CTS measures multiple overlapping of different sensory units and complex cortical integration the test is a good measure for assessing functional nerve regeneration after nerve repair

• CTS-6 Evaluation Tool: a validated clinical tool for diagnosis of CTS.

A score >12 is indicative of 80% probability of CTS. A score of >5 is indicative of 25% probability.

• • CTS-6 Evaluation Tool

Numbness predominantly or exclusively in median nerve territory +3.5 Nocturnal Numbness +4 Thenar atrophy and/or weakness 4/5 weakness or less +5 Positive Phalen test +5 Loss of 2-point discrimination Threshhold of 5mm +4.5 Positive Tinel sign +4

Surgery may cause:

• Scar formation
• Nerve damage
• Vascular injuries
• Incomplete release of the ligament
• Wound infections

Mental status parameters, alcohol usage decrease the final outcome of patients after their therapy.