Nail clubbing, also known as digital clubbing or clubbing, is a deformity of the finger or toe nails associated with a number of diseases, mostly of the heart and lungs. When it occurs together with joint effusions, joint pains, and abnormal skin and bone growth it is known as hypertrophic osteoarthropathy.Clubbing is associated with lung cancer, lung infections, interstitial lung disease, cystic fibrosis, or cardiovascular disease. Clubbing may also run in families, and occur unassociated with other medical problems.The incidence of clubbing is unknown; it was present in about 1% of people admitted to an internal medicine unit of a hospital. Clubbing has been recognized as a sign of disease since the time of Hippocrates. Causes
Clubbing is associated with

Lung disease:
Lung cancer
Interstitial lung disease most commonly idiopathic pulmonary fibrosis
Complicated tuberculosis
Suppurative lung disease: lung abscess, empyema, bronchiectasis, cystic fibrosis
Mesothelioma of the pleura
Arteriovenous fistula or malformation
Sarcoidosis
Heart disease:
Any disease featuring chronic hypoxia
Congenital cyanotic heart disease (most common cardiac cause)
Subacute bacterial endocarditis
Atrial myxoma (benign tumor)
Tetralogy of Fallot
Gastrointestinal and hepatobiliary:
Malabsorption
Crohns disease and ulcerative colitis
Cirrhosis, especially in primary biliary cholangitis
Hepatopulmonary syndrome, a complication of cirrhosis
Others:
Graves disease (autoimmune hyperthyroidism) – in this case it is known as thyroid acropachy
Familial and hereditary clubbing and "pseudoclubbing" (people of African descent often have what appears to be clubbing)
Vascular anomalies of the affected arm such as an axillary artery aneurysm (in unilateral clubbing)Nail clubbing is not specific to chronic obstructive pulmonary disease (COPD).
Subdural hygroma does not have internal membranes that can easily rupture like subdural haematoma, but hygroma can sometimes occur together with hemorrhage to become hematohygroma.Subdural hygromas most commonly occur when events such as head trauma, infections, or cranial surgeries happen in tandem with brain atrophy, severe dehydration, prolonged spinal drainage, or any other event that causes a decrease in intracranial pressure. This provides the basis for why subdural hygromas more commonly occur in infants and elderly; infants have compressible brains while elderly patients have a greater amount of space for fluid to accumulate due to brain atrophy from age. Signs and symptoms
Most subdural hygromas are small and clinically insignificant. A majority of patients with SDG will not experience symptoms. However, some commonly reported, but nonspecific, symptoms of SDG that have been reported include headache and  nausea. Focal neurologic deficits and seizures have also been reported but are nonspecific to SDG. Larger hygromas may cause secondary localized mass effects on the adjacent brain parenchyma, enough to cause a neurologic deficit or other symptoms. Acute subdural hygromas can be a potential neurosurgical emergency, requiring decompression. Acute hygromas are typically a result of head trauma—they are a relatively common posttraumatic lesion—but can also develop following neurosurgical procedures, and have also been associated with a variety of conditions, including dehydration in the elderly, lymphoma and connective tissue diseases. Diagnosis
In CT scan, subdural hygroma will have same density as the normal CSF. Meanwhile, in MRI, subdural hygroma will have same intensity with CSF.