Page 77 - JSOM Summer 2024

Discussion Given the frequent concurrence and overlapping comorbid-
ity of LPMCS and rhabdomyolysis, early measurement of CK
Despite its relative rarity, military personnel are at increased should be considered in the workup of severe back pain re-
risk for LPMCS, which is a challenging diagnosis because of fractory to conservative pain management. The AAOS clinical
its non-specific presentation, that overlaps with less severe pa- practice guidelines for ACS recommend assessment for acute
thology. A 2017 systematic review of acute lumbar paraspi- vascular ischemia with serum lactate based on moderate ev-
nal compartment syndrome identified only 21 unique cases, idence, with additional recommendations for both initial and
highlighting that these patients are predominantly males aver- serial intracompartmental pressure measurement, based on
aging 32.1 years of age, with exercise-induced, nontraumatic, moderate evidence. One study illustrated that the specificity
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low back pain refractory to opioid analgesia. The number of and sensitivity of elevated lactate for predicting ACS change
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reported cases increased to 37 in a 2021 systematic review, at different thresholds; at a measurement of 2mmol/L, lac-
in which men (mean age 30.9 y) performing intense physical tate is only 68.7% sensitive and 36.3% specific, whereas at
activity represented the majority of presentations. Of these 10mmol/L, sensitivity is 9.7% and specificity is 98.4%. Sim-
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37 cases, 22 were treated operatively with lumbar fasciotomy; ilarly, CK is poorly sensitive but highly specific for detecting
among the 20 patients who attended follow-up, 19 reported ACS at rising thresholds; CK greater than 2,000U/L is 4.6%
resolution of symptoms. In the cohort of 15 patients treated sensitive and 87.6% specific, while CK greater than 5,000U/L
nonoperatively, only 11 attended follow-up, with only 1 re- is 2.3% sensitive but 99.6% specific. 14
porting symptom resolution. 5
Fasciotomy is the definitive treatment for both ACS and
LPMCS can mimic more benign presentations of acute low LPMCS. For spinal musculature, the procedure entails in-
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back pain in its early stages and rapidly progress to more de- cision along the muscle’s longitudinal axis through the tho-
bilitating injury, including rhabdomyolysis. As with the pa- racolumbar fascia and paravertebral muscles to release the
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tient described in this case, specific red flags to monitor that longissimus, iliocostalis, spinalis, and/or multifidus as sur-
may differentiate LPMCS from back pain include pain refrac- veyed by MRI or a compartment pressure needle. In addi-
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tory to multimodal analgesic pharmacotherapy, severe focal or tion to fasciotomy, combat wounds resulting in LPMCS
muscle group tenderness to palpation, persistent symptoms at may require deep wound debridement of periosteum and
rest, and acute, progressive debilitation from activities of daily bone for hematoma evacuation to relieve compartment
living. Failure to relieve elevated compartment pressure within pressure. Although unstudied in LPMCS, prophylactic fas-
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as early as 2 hours can rapidly lead to tissue necrosis, but delay ciotomy with appropriate clinical suspicion prior to aeromed-
in receiving care is not a contraindication to fasciotomy, and ical evacuation is recommended to prevent complications of
post-surgical care is predominantly supportive, focusing on ACS, including muscle necrosis, infection, and amputation
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analgesia. Fasciotomy as late as 7 days after initial injury still (Figure 4).
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portends improved long-term outcomes relative to nonsurgical
intervention. 8 A single austere-environment military case report describes
a patient receiving a fasciotomy for LPMCS aboard a naval
While the most accurate available measure for diagnosing vessel, with incisions loosely closed with vessel-loops and
ACS is direct compartment pressure greater than 30mmHg, subsequent negative pressure wound vacuum application.
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the American Academy of Orthopedic Surgeons (AAOS) rec- Only one case report demonstrated the effectiveness of hyper-
ommends against single-measurement pressure values for di- baric oxygen with alkalinizing diuresis without fasciotomy
agnosis and recommends combining compartment pressure in treating LPMCS; hyperbaric oxygen with urinary alka-
with clinical exam findings. Specifically, there is no consen- linization may be resource-limited in the forward deployed
5,7
sus on an optimal threshold pressure with adequate specific- environment. 17
ity to accurately diagnose ACS from a single measurement.
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The average compartment pressure in LPMCS is reported at The patient described in this report had multiple acute and
91.8mmHg, and there is no correlation between compart- chronic risk factors for both rhabdomyolysis and spinal com-
ment pressure above the accepted threshold for diagnosis of partment syndrome, including demographics, regular supple-
compartment syndrome and severity of disease. Furthermore, ment use, and high-intensity physical activity concurrent with
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measurement of compartment pressure is unreliable in the an increase in baseline physical activity. 7,10 Additionally, this
combat setting owing to variable pressure attenuation within patient’s case warranted an increased index of suspicion for se-
a muscle compartment in as few as 5cm from the maximal vere pathology as he returned to the ED for a third visit with in-
point of injury. 12 tractable pain refractory to a multimodal pain control regimen.

MRI most accurately diagnoses myonecrosis in the setting
of LPMCS, identified as hypoenhancement within the mus- Conclusion
cle compartments indicative of tissue ischemia. Some studies Despite its relative rarity in the general population, LPMCS
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suggest evidence of paraspinal muscle swelling detected via should be considered among military personnel when evalu-
CT scanning may correlate with LPMCS diagnosis, though ating back pain refractory to initial treatment. Severe, debil-
this finding has no reported sensitivity or specificity. Early itating paraspinal muscle pain refractory to multimodal pain
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research has begun exploring the utility of ultrasound in ACS, management strategies is a diagnostic red flag. Workup should
but no modality yet exists for assessment of paraspinal mus- include lactate measurement, comprehensive metabolic panel,
cle compartments. In vitro modeling has been used to assess CK, and imaging as available, ideally with MRI. Diagno-
the feasibility of estimating whole compartmental elastic- sis is based on a combination of clinical suspicion and serial
ity and its correlation with intracompartmental pressure by compartment pressure measurement in the hospital setting,
ultrasound. while provider judgment in the combat setting warrants early,
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