How to Detect the Presence of Nail Clubbing & Is Nail Clubbing Reversible or Irreversible?

Nail clubbing also known as finger clubbing and digital clubbing, is basically a deformity of terminal soft part of finger that is distal phalanges along with nails and toenails. Let us understand about nail clubbing in detail. Presenting here are the causes, symptoms, grades, diagnosis and treatment of nail clubbing. As nail clubbing is an important sign of worsening conditions, knowing about the possible causes and its symptoms can help to get the right treatment in time.

Nail clubbing occurs due to structural changes at the base of the nail, which results in swelling of distal phalanges and convexity of nails. Subsequently, there is loss of the normal angle seen between the nail and the nail bed and fingertips appear broader and rounder. Drumstick fingers or watch-glass nails are other names for clubbed fingertip owing to its appearance. Nail clubbing is often a clinical finding, it is not an independent cause of mortality

Most common test to detect nail clubbing is Schamroth sign. In this, both the index fingers are placed touching each other, pointing downwards. In negative sign, a diamond shaped window is formed between the nails of the two fingers. When the test is positive, the window looks obliterated.

On the basis of causes, nail clubbing may be divided in two types

1. PRIMARY : Some of the primary causes of nail clubbing include

   1. Hereditary
   2. Idiopathic or due to unknown cause

2. SECONDARY: Nail clubbing may be due to secondary causes as well. The secondary causes of nail clubbing are commonly seen in people experiencing other medical conditions and are already under treatment or if the condition is undiagnosed.

   Nail clubbing may appear as a symptom of underlying diseases like:

   1. Pulmonary Disease: Bronchiectasis, lung abscess, chronic lung infection, tuberculosis with secondary infection, bronchogenic carcinoma, cystic fibrosis etc.
   2. Cardio-Vascular: Congenital heart disease, infective endocarditis,
   3. Gastro-intestinal: Inflammatory bowel disease, ulcerative colitis, C1rohn’s disease, cirrhosis of liver etc.
   4. Endocrine: Acromegaly, iatrogenic myxedema, exophthalmoses.
   5. Miscellaneous Causes: In heroin addicts due to chronic obstructive phlebitis (inflammation of vein)

Bulbous enlargement of the distal portion of a digit or the finger is the main symptom of nail clubbing. Normally, in healthy people, the angle made by the proximal nail fold and nail plate of normal distal digit, also known as Lovibond angle is either less than or equal to 160°.

In clubbing, the angle flattens out and increases as the severity of the clubbing increases. The angle greater than 180°confirms the presence of clubbing.

An angle between 160-180° falls in early stages of clubbing or a pseudo clubbing phenomenon.

As a part of the common symptoms of nail clubbing, here are some worth mentioning

1. Nail clubbing develops first in the thumb and forefinger and then appears in other fingers.
2. Abolition of the angles along with softening of the nail bed is the first clinical sign and symptoms of nail clubbing.
3. In contrast to normal healthy firmly attached nails may seem to float.
4. Swollen and bulging fingertips and curvature of the nails pointing downward is the classic feature of this deformity.
5. In lower extremities, clubbing of the toes is difficult to determine as they normally appear bulbous but is often recognizable in the great toe.
6. In mild cases though, minimal changes of the toe and slight pain are sometimes expressed by patients.

On the basis of its appearance nail clubbing may appear as

1. Unilateral Nail Clubbing- This is seen only on one side. This type of nail clubbing commonly appears in Pancoast tumor, subclavian and innominate artery aneurysm,
2. Unidigital Nail Clubbing- This is seen only in one finger. It commonly appears in case of injuries or gout deposit
3. Symmetrical and Bilateral Nail Clubbing– These are commonly seen in respiratory, gastric and other causes.

Early detection and prompt treatment of underlying conditions causing nail clubbing are the key factors to reverse the clubbed finger deformity. Once collagen deposition has set in and configuration has been disturbed along with substantial chronic tissue changes it is difficult to reverse the condition and clubbing becomes irreversible.

Depending upon the presentation, stages or grades of nail clubbing are –

• Grade 1 Nail Clubbing- Softening and fluctuation of the nail bed
• Grade 2 Nail Clubbing – Stage of mild clubbing, normal 160° angle between nail bed and nail fold is increased
• Grade 3 Nail Clubbing – Stage of moderate nail clubbing, accentuated convexity of the nail
• Grade 4 Nail Clubbing – Stage of appreciated nail clubbing, fully clubbed fingertip appearance present
• Grade 5 Nail Clubbing – Stage of hypertrophic osteoarthropathy, development of shiny glossy change in nails and adjacent skin with longitudinal striations

Nail clubbing can be confused with other similar conditions, hence it is necessary to properly evaluate and differentiate between them.

• Pseudo-clubbing – There is curvature of nails longitudinally as well as transversely while normal Lovibond angle remains undisturbed.
• Hypertrophic Osteoarthropathy – Nail clubbing is present along with joint swelling and periostitis of long bones.

Nail clubbing is just a clinical finding caused by underlying disease. Therefore diagnostic studies of nail clubbing are as per the underlying disease and usually are blood tests and imaging technologies. The diagnosis of nail clubbing can be done with physical examination and the exact underlying condition can be detected with necessary investigations.

Laboratory Tests: Blood and serum tests according to the possible medical condition, based on symptoms and clinical appearances.

Imaging Technology:

• X-ray is used to check evident presence of bone dissolution and bone deformation.
• Technetium Tc 99m – Skeletal Imaging provides good quality views of bone changes in clubbed digits and also shows increased levels of blood flow and softening of surrounding tissues.
• Thermography used to monitor increased temperature in the distal digits caused by vasodilation.
• Positron emission tomography is used to study glucose metabolism of clubbed digits. Computed Tomography (CT Scan) or Magnetic Resonance Imaging (MRI) for evaluation of primary causative factor of clubbing.

Though treatment of underlying pathological condition may decrease the nail clubbing, there is no specific treatment for this disorder. Studies show that some patients respond well to Etoricoxib (Arcoxia), a non-steroidal, anti-inflammatory drug called as NSAIDs. It soothes the pain and swelling associated with nail clubbing and is taken once a day on a full stomach. This should be used under doctor’s guidance only as so many side effects and contraindications have been observed during its use.

Some natural remedies are also in practice to soothe the sufferings of nail clubbing. These conservative treatments are:

• Application of warm olive oil.
• Soaking clubbed nails in a mixture of tomato juice or lemon juice.
• Soaking clubbed nails in a mixture of 3 tablespoons of olive oil and one tablespoon lemon juice.
• Sliced lemons rubbed over the nails in a 5 minute period also promote natural nail growth.
• Consumption of foods rich in gelatin such as jellies can also be a cure as well.
• Consumption of vitamin E rich foods like green leafy vegetables etc. on a regular basis.
• Drops of tea tree oil on the nail beds as well as use of essential oils for massaging the nails.
• Salt water treatment for 5 minutes on the nail beds
• No cutting of cuticles.

Though many theories had been proposed, the exact pathology of nail clubbing remains unknown. Different pathological processes may follow different pathways to a common end. Beginning with increased interstitial edema, which results in alterations in size, composition and configuration, lastly to the formation of the clubbed digit. Distal digital vasodilation is the prime common factor in most types of nail clubbing that sources increased blood flow to the distal portion of the digits. This vasodilation may be due to circulating or local vasodilator, neural mechanism, hypoxia, genetic predisposition, other mediators or a combination of these factors.

In a recent study, platelet-derived growth factor released from fragments of platelet clumps or megakaryocytes has been proposed as the responsible factor for finger clubbing. Growth-promoting activity given away by this factor causes increased capillary permeability and connective tissue hypertrophy.

Another proposed theory is of neural mechanism on special attention to the vagal system since regression of clubbing after vagotomy has been reported. Genetic inheritance and predisposition also may play a role in clubbing and may be one of the possible causes of nail clubbing.

Nail clubbing is a presentation of an underlying problem. Hence, it is important to seek medical advice, if such nail changes are noted. Timely treatment can help to control nail clubbing and also provide proper treatment for the underlying cause.