Assessment of the lymphedema patient

History

Detailed history taking is important. First, one wants to know how lymphedema started, was there an instigating factor, or did it arise de-novo? Is this an isolated case in the patient’s family, or do other family members also have lymphedema? In other words, is this congenital or acquired. If there was an instigating factor, what was it, and how long ago did this occur? Has the patient had a lymph node dissection and/or radiation? A travel history is important since we know that the leading cause of lymphedema worldwide is filariasis^[1]. Even though I live and practice in the United States, I have several patients in my practice whose lymphedema was caused by filaria. Whether the patient has spent time in an area where filariasis is endemic is, therefore, something one needs to know. The duration of the condition is also important. We know that the best results from lymphedema treatment are obtained early in the course of the disease. Duration will also give an idea of how advanced the condition is likely to be, which may impact treatment. Cellulitis is a common accompaniment of lymphedema, and each episode of cellulitis leads to further damage to the lymphatic system^[2]. For this reason, a history of infection and its frequency is important. How does the patient manage the swelling? Do they wear compression and, if so, is it effective? Finally, we want to know what treatment the patient has had and, more importantly, how they responded to that treatment.

Physical examination

On completion of the history, the patient should be examined. There are several things that we look for specifically in the patient with lymphedema:

1. How big is the limb and, if it is unilateral, how does it compare with the contralateral side?

2. Are there trophic skin changes? [Figure 1]

Figure 1. This patient with extreme late-stage lymphedema shows trophic skin changes. There are folds of edematous skin and thick rigorous skin, giving rise to fissures and increasing the risk of infection.

3. Is there any sign of infection?

4. Is there pitting edema? [Figure 2]

Figure 2. Pitting edema is elicited by firmly pressing on the limb with the thumb for 1 min. Here we see the imprint of the thumb indicating fluid in the tissues. As lymphedema progresses, pitting edema is less prevalent because of the accumulation of fibro-adipose tissue.

Limb circumference

Most practitioners measure limb circumference, and this is an important tool not only as a static evaluation but also as a dynamic, ongoing measurement to assess the patient’s progress. However, limb circumference needs to be standardized if it is to be of any use. So, the same measurement points need to be chosen.

Limb volume

Limb volume is of greater use than mere limb circumference measurements. Limb volume can, however, be calculated from limb circumference measurements using the inverted cone formula. Brørson has published the formula based on 4 cm increment measurements^[3].

The traditional way of measuring limb volume was with water displacement. While this works, not every clinic is equipped to do these measurements.

Optoelectronic volumetry using a Perometer is a very accurate way of measuring limb volume^[4]. Perometry uses a frame with light transmitters on two sides and photo-sensors on the opposite sides. The limb to be measured is placed within the frame, and the frame is moved along the limb to give a very accurate measurement of the limb volume. Hands and feet are not measured using this technique.

Bio-impedence spectroscopy

This test measures the time taken for a small electrical current to pass through the tissues. It is based on the premise that the amount of opposition to the flow of electrical current (impedance) through the body is inversely proportional to the volume of fluid in the tissue.

In lymphedema, tissue impedance decreases, which is a useful test that can be used for initial assessment and to measure the patient’s response to treatment^[5]. However, it may be misleading in early or pre-clinical lymphedema, where the bio-impedence may be normal. Therefore, it is most useful as a trend measurement over time.

Imaging

Several imaging modalities can be used to assess the lymphedema patient. As with the assessments above, no one imaging modality is used for the complete assessment. Taken together, though, they provide the best information on what is going on with the patient.

(1) Lymphoscintigraphy [Figure 3]: This involves the injection of filtered sulphur colloid, Technetium 99, into the dermis of the affected limb^[6,7]. The Technetium is then transported to the draining lymph nodes. This text gives excellent information on the function of the lymphatic system, and if I have any doubt as to the diagnosis, this is the imaging of choice. It tells you whether the lymphatic system is normal or not. However, it doesn’t give good anatomic information so that if surgery is being planned, more information is needed. In particular, it doesn’t show the superficial lymphatics in any detail.

Figure 3. This is a lymphoscintigram of a post-mastectomy patient. Notice the absence of Technetium pickup in the right axilla indicating distal obstruction of the lymphatic system.

(2) Fluorescent lymphangiography: This is achieved with the injection of indocyanine green (ICG). ICG is a fluorescent dye activated by a laser light source, and the fluorescence can be visualized with a near infra-red camera [Figure 4]. The advantage is that it gives excellent information on superficial lymphatics. Its disadvantage is that it only penetrates about 1.5 cm, so it doesn’t give any information on the deeper lymphatics or other structures in the limb. The significance of the different patterns of ICG that are seen, linear, splash, stardust, and diffuse, have been elucidated and correlate with decreasing circumference of the lymphatics and increasing sclerosis. Apart from its use as a diagnostic tool, ICG is important for mapping the lymphatics at the time of surgery so that incisions can be planned accurately^[7,8].

Figure 4. This is the splash pattern seen with ICG lymphangiography in early lymphedema. The lymph is mainly contained within lymphatic channels, but a “splash” of ICG is also seen in the soft tissues. ICG: Indocyanine green.

(3) MR lymphangiography: There are several techniques for using MR in assessing the lymphedema patient. Imaging can be achieved with or without contrast. A technique known as the “dark blood” technique can be used [Figure 5]. The contrast used is Gadolinium. The Dark Blood technique involves the intravenous injection of Feraheme, which essentially blacks out the venous signal and eliminates the difficulty of deciding what a vein is and what is a lymphatic^[9,10]. However, one of the most significant advantages of MR is that it gives accurate information on other conditions appearing in the limb. Feraheme has been associated with hypersensitivity reactions as well as anaphylactic shock. Hypotension has also been reported^[11].

Figure 5. (A) MR Lymphangiogram of a patient with lymphedema of the left leg. Note the difficulty of identifying veins and lymphatics. (B) The same patient with Feraheme producing a “dark blood” image clearly showing lymphatic channels and no veins.

(4) Ultrahigh-frequency ultrasound: This is the newest imaging modality to be used. It has the advantage of identifying lymphatics and veins, and the ultra-high-frequency (up to 70 MHz) probes give an excellent definition^[12]. The significant disadvantage of UHF: ultrasound is lack of user-friendliness and the time is taken to do an examination.

Conclusion

Several treatment options exist for patients with lymphedema. Choosing the correct treatment is vital. Patient assessment is of paramount importance in achieving this. There is no one test or finding that is pathognomic for lymphedema, and we need to use multiple modalities to conduct a proper assessment. These assessments are not just useful in the initial evaluation of these patients. They are also extremely useful in following our patients and assessing the results of our treatment.