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Differential Diagnosis (Radiological)

In the early stages the direct, specific changes of leprosy must be differentiated from all causes of small cystic lesions without bone reaction, and all factors which may cause osteoporosis; the radiologist can only be accurate if the clinical findings are carefully related. The changes in the terminal phalanges in leprosy may be mimicked by scleroderma, psoriasis, Raynaud's disease, and frostbite (unlikely in most countries where leprosy is common). The deformities caused by mycotic infection of the feet (and to a lesser extent of the upper limbs) and by all soft tissue infections and vascular disorders will be included in the differential diagnosis. In the later stages all the neuropathies, particularly syphilis, diabetes, congenital indifference to pain, and syringomyelia, must be considered.

Fortunately, in the majority of cases, the clinical examination of the patient provides the correct diagnosis, particularly when there is severe localized skeletal deformity in the absence of generalized clinical ill health.

Radiographic Examination

The radiography of leprosy, particularly of the deformed feet, is of great importance but it is not necessary to examine every patient routinely in the absence of clinical findings. The clinical conditions which are most likely to cause bone changes are as follows: (1) ulceration of the feet or hands; (2) deformity of the hands or feet due to either contraction or subluxation; (3) local inflammation or swelling; (4) the history of an acute lepra reaction in any localized area; (5) preoperatively, particularly to exclude unsuspected bone cysts, stress fractures, or osteoporosis.
Serial examination every 6 months is essential in such cases and the technique must be identical on each occasion.

Radiographic Technique

A 15° anteroposterior (AP) oblique view of the foot is preferred to the routine AP view; there is less overlap of the small tarsal bones and there will be better definition of the individual digits. To this should be added a lateral view of the tarsal bones, which ideally should be taken in a weightbearing position; particular attention should be given to any rough area of underlying bone which may cause excess pressure on the soft tissues. (Care should be taken to demonstrate the soft tissues on the radiographs.)

An excellent review of the radiographic examination of the feet is given by Grace Warren in Leprosy Review 44: 131-138, 1973. She provides a method of standardization with the use of simple devices which would be of great help to anyone involved in the routine radiologic examination of patients with leprosy.

Treatment

Radiologists should be aware of the difficulties and length of treatment. In leprosy, of all diseases, the diagnosis should be accurately established beyond doubt before treatment is started because the psychological readjustment is considerable. Nevertheless, early treatment will prevent many deformities and much hardship. Most patients are treated at mobile or static clinics and this has helped to eradicate infective sources. Admission to hospitals or sanitoria is only needed for special rehabilitation. The drugs act slowly and should be maintained for long periods. Physiotherapy and exercise of the muscles are very important to prevent contractures and keep good muscle tone. Surgical procedures are aimed at restoring function, overcoming the deformities, or providing cosmetic improvement to make the patient socially accepted (Fig. 34.27).

Education of the public and patients is part of the treatment. Restoration of the patients to society and making the independent, to work with protected tools or at a modified occupation, is the ultimate responsibility of the physician. A thorough understanding of the pathological processes and acurate interpretation of the radiographic findings may help to make this restoration possible.

Acknowledgement. This chapter follows from Chapter 31 of the First Edition, which was written with the valuable advice of Dr. A. C. Johnson, MB, BS, PhD, FRCR, formerly Professor of Radiology at the Christian Medical College, Vellore, India. His personeal experiance with leprosy patients in India provided a very firm basis, to which new information has been added to summerize the enormous progress which has been made against this ancient disease.

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Fig. 34.27. A, B Side and front views of the "sinking nose" in leprosy, with collapse due to loss of the lateral cartilage, and resorption of the maxillary spine, the turbinates, and the maxillary fossa. C Lateral view of the facial bones using a wedge filter technique. Loss of the maxillary spine and the lamina dura near the upper incisors is seen. D Posterior displacement of the nose - or "sinking in" - occurs as a result of resorption of the maxillary fossa and atrophy of the turbinates. Clinicoradiological assessment is necessary before reconstruction. 3-dimensional imaging and computer simulation is making the process of reconstruction easier and more accurate.

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