Plexus-neuropathy due to ilio-psoas hematoma in 4 COVID patients

Dear Editor,

Plexus neuropathies caused by retroperitoneal lumbar hemorrhages are rare and tend to be related with coagulation disorders, iatrogenesis, or traumas.^1,2 In patients with the 2019 coronavirus disease (COVID-19), the most relevant circumstance associated with this entity was anticoagulation, which was used massively in an attempt to avoid the intense thrombotic effects caused by the viral infection.

We hereby describe four cases of patients with a severe infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who developed a lumbar plexus neuropathy secondary to retroperitoneal bleeding with involvement of the iliopsoas muscle, and discuss the probable pathogenic relationships based on the current knowledge available on the infection.

All patients presented with intense and acute weakness in their lower extremities after being hospitalized in the Intensive Care Unit (ICU), receiving anticoagulation therapy, and developing bilateral pneumonia in the context of COVID-19, which required the administration of mechanical ventilation in a ventral decubitus position due the onset of severe respiratory failure. Our study population consisted of three men and one woman aged 73, 69, 65, and 55 years, respectively. All of them had been hospitalized in the ICU for over three weeks and exhibited crural paralysis with a lumbar myotomic distribution in vertebral bodies L2, L3, and L4, and, in two cases, paresis in relation to vertebrae L5 and S1. The time elapsed until reaching the diagnosis was 5–7 weeks. The entity was characterized by electrophysiology, which revealed the anatomical structure of the external trajectory toward the intervertebral foramen (peripheral nerve plexus); severe subacute denervation in the iliopsoas, quadriceps, adductor magnus, and adductor longus muscles; and partial denervation in the anterior tibial, tensor fasciae latae, gluteus medius (myotome 5), gastrocnemius medialis, and gastrocnemius lateralis (S1) muscles. The imaging studies performed revealed retroperitoneal hematomas affecting the iliacus muscles and, especially, the psoas major muscles, which exhibited significant muscle growth and preferential displacement toward the midline (Fig. 1). In addition, all four patients had laterality consistent with their clinical deficiencies and electrophysiological signs.

Figure 1.

Top: Nuclear magnetic resonance scan. Patient 1. Subacute hematoma in the iliacus muscle, with cranial progression over the psoas major muscle and significant anterior pararenal and axial deviation, measuring 84 mm (craniocaudal [CC]) × 64 mm (anteroposterior [AP]) × 43 mm (transversal [TR]).

Bottom: Computerized axial tomography scan. Patient 3. Subacute intramuscular hematoma in the left psoas major and iliacus muscles, measuring 100 mm (CC) × 90 mm (AP) × 70 mm (TR).

Approximately 7% of anticoagulated patients experience spontaneous deep bleeding, of which 0.5% of cases are detected in the iliopsoas muscles.³ Sixty percent (60%) of these episodes are diagnosed in the ICU³ and cause significant increases in mortality and morbidity rates. Other associated factors are advanced age, obesity, cough, stressful manipulations owing to the patients’ hypomobility, and prolonged maintenance of the supine, lateral, and ventral decubitus positions, this last one being widely used in clinical practice. These factors are known to be strongly associated with diffuse microvascular atherosclerosis or, in other words, fragile blood vessels that can be ruptured even as a result of minor traumas.

It has been confirmed that the hematogenous route is one of the main entry ways used by the virus.⁴ This coronavirus has the ability to bind to the angiotensin-converting enzyme (ACE) membrane receptor of several cell populations, including the microvascular endothelium, where the virus causes immediate endothelitis and an intense inflammatory response, which it exploits, among other things, to enter the immune cells and disseminate in the form of a “Trojan horse”. The massive binding of the virus to this receptor causes a large amount of angiotensin II to remain unbound within the blood stream, thus causing, among other effects, microvascular vasoconstriction and hypercoagulability, both of which result in ischemia and thrombogenesis. These are the events that have caused a multitude of serious complications and forced the massive use of anticoagulant treatments in the context of this pandemic.

The most common neurological complication of iliopsoas hemorrhage is femoral neuropathy and, less frequently, lumbar plexopathy and femoral or obturator neuropathies. The lumbar retroperitoneal space contains both the lumbar plexus and the femoral and obturator motor nerves (Fig. 1), whose interest lies in the fact that they both run through the psoas major muscle.⁵ Neural vascularization in the upper region of this muscle is low, even lower in the event of increased pressure due to intramuscular bleeding within a space surrounded by a hard aponeurosis; that is, a full-fledged compartment syndrome. All our patients exhibited significant, synchronous, and homogeneous impairments during leg adduction, hip flexion, and knee extension, which were indicative of intramuscular involvement. The concomitant association of an L5 and S1 plexus radiculopathy in two patients was caused by the existence of hematomas spreading posteriorly toward the middle and lower regions, where the lumbosacral plexus is supported by structures that are difficult to deform.

In some cases, COVID-19 has also resulted in severe iatrogenesis, particularly as a result of the treatments administered to control the intense thrombogenesis associated with this condition. In this paper, we describe the case of several patients with a severe SARS-CoV-2 infection who were treated with anticoagulants and had prolonged stays in the ICU due to presenting with a plexus neuropathy secondary to deep retroperitoneal bleeding, with particular involvement of the psoas major muscle. It remains to be determined whether their prolonged maintenance in the ventral decubitus or the postural changes performed due to their hypomobility could have favored the retroperitoneal bleeding and, therefore, the neurological complication described.