Thursday, October 14, 2010

Swan-neck deformity

A swan-neck deformity, defined as proximal interphalangeal (PIP) joint hyperextension with concurrent distal interphalangeal (DIP) joint flexion, occurs in approximately 50% of patients with rheumatoid arthritis RA. However, swan-neck deformity is not unique to RA, because it may also be congenital or traumatic in nature.

It may also caused by:
# mallet finger (due to rupture of lateral slips at their junction with bone)
# cerebral palsy (due to muscle imbalance)
# congenital joint laxity

The pathophysiology of the swan-neck deformity begins with flexor synovitis, which increases the flexor pull on the MP joint. Constant efforts to extend the finger against this pull lead to stretching of the collateral ligaments and the volar plate at the PIP joint.

In a normal finger, intrinsic muscles (interosseous and lumbrical) insert into the lateral bands and serve as flexors of the MP joint and extensors of the PIP and DIP joints by being located volar to the MP joint axis and dorsal to the PIP and DIP joint axes.

In a rheumatoid finger, the lateral bands are constrained in their dorsal position, upsetting the flexor-extensor balance. In this position, the lateral bands increase the pull of the long extensor tendon's central slip, which attaches to the dorsal base of the middle phalanx. The increase of flexor profundus tension resulting from hyperextension of the PIP joint leads to a reciprocal flexion of the DIP joint. Progressive disease causes joint destruction and fixed contracture.

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How to identify Hematoma in Mammography ??

In this article we will show WELL-CIRCUMSCRIBED and ILL-DEFINED HEMATOMA as seen in Mammogaphy...

Most commonly caused by blunt or surgical trauma, although hematomas may develop in patients who are anticoagulated or have clotting abnormalities. The combination of hemorrhage and edema more commonly results in an ill-defined mass or a diffuse area of increased density. Although the mammographic findings simulate carcinoma, a history of trauma suggests a conservative approach. Follow-up examinations show gradual decrease in size or even disappearance of the lesion. An organized hematoma may occasionally persist as a more sharply defined mass.

Imaging Findings:
Medium to high-density mass, often having slightly irregular margins. Overlying skin edema is usually present in the acute stage if the hematoma is secondary to trauma.
Hematoma. (A) Mammogram of a firm, palpable mass that arose at a recent biopsy site shows a dense lesion associated with skin thickening (arrows). (B) Three months later, there has been almost complete resolution of the hematoma with only minimal residual architectural distortion (arrows).

Overlying skin thickening from edema and bruising may simulate carcinoma. Hematomas tend to resolve within 3 to 4 weeks.

Imaging Findings:
May appear as an ill-defined lesion (more commonly a relatively well-defined mass or a diffuse increase in density).

Hematoma. Ill-defined area of increased density (arrows) in the area of a lumpectomy performed 2 weeks previously.


Presenting as sciatica,Lesion was Sacral herpes zoster

A 70y-old man was admitted to hospital because of multiple injuries from a traffic collision. On day 16 after admission, he started to complain of pain, weakness and numbness in his right leg!!

A contrast-enhanced CT scan of the lumbar spine showed a displaced sacral fracture with compression of the S1 ventral ramus.The patient’s symptoms persisted despite of treatment with diclofenac, chlor-zoxazone, fursultiamine and betamethasone.
Severe tingling pain and allodynia (pain with light touch) developed seven days later. Thirty days after admission, several painful grouped erythematous plaques with vesicles were found on his right buttock and the posterior aspect of his right leg (The figure below).

The distribution was consistent with the S1 dermatome, and a diagnosis of herpes zoster was made. The patient was prescribed valacyclovir hydrochloride, 500 mg three times daily for 5 days. The cutaneous lesions healed about seven days after the treatment was started and the tingling pain resolved gradually. The patient was discharged  42 days after admission.

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