Page 121 - Journal of Special Operations Medicine - Spring 2017

Figure 4 Algorithm for evaluation and treatment of meralgia superior iliac spine or at the point of maximum tender-
12
paresthetica (modified and updated from Grossman et al. ness. The test is positive if symptoms are quickly re-
25
and Williams and Trizil ). LFCN, lateral femoral cutaneous lieved and this lasts for 30–40 minutes. It is sometimes
nerve; NSAID, nonsteroidal anti-inflammatory drug. useful to retest patients who do not respond 3–4 weeks
later. 26,28,29

Other specialized techniques for the diagnosis of MP
may also be useful, especially when the history and
physical examination have not been conclusive. These
include somatosensory evoked potentials, sensory nerve
conduction studies, high-resolution ultrasound, and
magnetic resonance imaging (MRI). In one study, so-
30
matosensory evoked potentials for MP involving stimu-
lation of the lateral aspect of the distal third of the thigh
had a sensitivity of 84% and specificity of 100%, stim-
ulation of the LFCN below the anterior superior iliac
spine had a sensitivity of 53% and specificity of 100%,
and sensory nerve conduction studies had a sensitivity
of 65% and a specificity of 100%. The sensitivity/speci-
ficity of high-resolution ultrasound for diagnosis has
not been determined, but the technique may useful for
comparison of morphological differences of the LFCN
on the affected and unaffected sides. 31,32 MRIs read by
experienced radiologists had intraobserver reliability of
≥79%, sensitivity of ≥71%, and specificity of ≥94%
for the detection of clinically diagnosed MP. MRI or
33
other imaging techniques would also be helpful to in-
vestigate a suspected intraabdominal mass compressing
the LFCN. 23

Treatment
the force for 45 seconds. If symptoms are reduced, the The symptoms of MP may be mild and resolve spon-
test is positive. The downward pressure presumably re- taneously or be more severe and limit function. 5,8,26,34
laxes the inguinal ligament and reduces compression on If the symptoms are related to load-carriage issues, the
the LFCN, leading to the reduction in symptoms. The nature of the compression should be identified because
pelvic compression test is reported to have a sensitiv- symptoms generally resolve with removal of the com-
ity (i.e., the ability to detect the disorder) of 95% and pression 5,10 (e.g., by changing the configuration of the
specificity (i.e., the ability to identify those without the carried loads or the position of belts). Initial treatment
disorder) of 93%. 26,27 with nonsteroidal anti-inflammatory drugs (NSAIDs)
and ice applications (30 minutes three times per day)
For the femoral nerve neurodynamic test, the patient may assist in relieving pain associated with inflamma-
lies on the unaffected side, grasps the knee on the unaf- tion of the LFCN. 12,25 Topical treatment with 0.025%
36
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fected leg to achieve full hip flexion, and flexes their capsaicin cream or 0.1% tacrolimus has also shown
neck toward the knee. The evaluator hooks his or her to be helpful in reducing pain.
hand under the calf of the affected leg and grasps the
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knee with one hand, pushing slightly on the back of the A systematic review evaluated the effectiveness of vari-
hip with the other hand. The evaluator slowly bends the ous forms of treatment for MP. The review included
patient’s knee and abducts the hip of the affected leg to observational studies in which there were at least five
place tension on the lateral femoral cutaneous nerve. A cases and a follow-up of at least 80% of cases for at
positive test is reproduction of the patient’s specific MP least 3 months. One study reported that 18 (62%) of
symptoms rather than just a normal stretch sensation. 26 29 patients recovered completely without intervention.
Four studies involving injection of corticosteroids or lo-
Slightly more invasive is a diagnostic nerve block using cal anesthetics found recovery or improvement in 130
5–10mL of 1% lidocaine or procaine. The anesthetics (83%) of 157 of combined cases. Nine surgical studies
can be injected 1cm medial and inferior to the anterior involving decompression of the nerve showed benefit in

Load Carriage Paresthesias (Part 2) 97