Introduction

SARS-CoV-2 infection (COVID-19) has become a pandemic, and currently, there are no definite treatment options. This infection mostly affects the respiratory system, but extra respiratory multi-systemic involvement has also been reported (Casadevall and Pirofski 2020; Wang et al. 2020; Farahani et al. 2020). Neurological manifestations are rare but reported during the acute phase and the treatment period (Ashrafi et al. 2020 April). In particular, SARS-CoV-2 is a neurotrophic and neuro-invasive virus, and experimental animal studies have reported the association of acute flaccid paralysis (AFP) and demyelination with this infection (Brison et al. 2011). However, SARS-CoV-2 infection has not been reported as a cause of AFP until now (Dominguez et al. 2009). Nonetheless, few studies have reported post-infectious acute myelitis as a possible COVID-19 complication (Zhao et al. 2020; Baghbanian and Namazi 2020). Here, we report a case of early-onset ATM following SARS-CoV-2 infection.

Case report

A 63-year-old Caucasian man, with no history of trauma, experienced a sudden loss of control over both lower limbs, absent sensation from the chest below, constipation, and urinary retention, after the onset of a flu-like syndrome. The patient stated that he had fever, fatigue, sore throat, and runny nose, but no shortness of breath, about 4 days before his neurological complications. He was a known case of controlled type 2 diabetes, chronic renal failure, and ischemic heart disease. On arrival, he had 38.6 °C oral temperature, a blood pressure of 155/95 mmHg, 98 heartbeats per minute, a respiratory rate of 21 breaths per minute, and 91% saturation in pulse oximetry on room air. No prominent abnormal finding in cranial nerves or neck rigidity was detected. Although normal muscle bulk was found in all four extremities, both lower limbs were hypotonic. Besides, while muscle forces were 5/5 in upper limbs, they were graded as 1/5 in both lower limbs. All modalities of sensation were diminished below the T8 level. The perianal sensation was absent; however, deep anal pressure awareness and bulbocavernosus reflex were present. Distal tendon reflexes were bilaterally absent in lower limbs but normal in upper limbs. Besides, superficial abdominal reflexes were present in upper quadrants and absent in lower quadrants. Plantar reflexes were bilaterally mute, and cerebellar signs were absent. Also, bilateral pathological signs were negative.

Regarding the COVID-19 outbreak, RT-PCR was done on a swab test of nasopharyngeal mucosa and reported positive. Subsequently, chest X-ray and HRCT revealed severe bilateral pulmonary involvement (Fig. 1).

Fig. 1
figure 1

a Posteroanterior chest X-ray; b a slice of chest HRCT scan; c–e spinal MRI with gadolinium contrast agent, c, d sagittal T2 views, e sagittal T1 view

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According to the then national COVID-19 treatment protocol, hydroxychloroquine (400 mg PO BID on the 1st day and then 200 mg BID for 10 days), azithromycin (500 mg PO daily for 5 days), and ritonavir (PO daily for 10 days) were administered. Furthermore, neurological manifestations were investigated. Brain CT scan, MRI, and contrast-enhanced MRI were reported as normal; thus, a lumbar puncture was done. Significant CSF findings and main laboratory results are summarized in Table 1. Besides, spinal contrast-enhanced MRI showed an extensive increased T2 signal that involved central gray matter and dorsal columns. The cord was expanded between C7 and T12. Also, a linear enhancement in the sagittal plane was seen posteriorly within the mid and lower thoracic cord (Fig. 1).

Table 1 Significant laboratory findings
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Subsequently, comprehensive laboratory tests were done to rule out the differential diagnoses (Table 2). Regarding the clinical presentation and paraclinical findings, acute transverse myelitis (ATM) as a probable complication of COVID-19 was considered the most plausible diagnosis.

Table 2 Differential diagnoses and the tests used for ruling them out
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After establishing the diagnosis, IV methylprednisolone (1 g/day for 3 days and then tapered to 1 mg/kg/day) was added to the treatment regimen. Over the next 3 days, his clinical condition deteriorated. He experienced intensifying lower thoracic pain, progressive hypoesthesia, and gradual debilitating dysesthesia characterized by numbness and ice-cold sensation. Subsequently, methylprednisolone was replaced by IV human immunoglobulin (25 g daily for 3 days), resulting in drastic clinical improvement within the next days. One week later, the patient was able to walk unassisted, with complete resolution of neurologic manifestations. Five weeks after admission, with regular and thorough rehabilitation sessions, he was discharged home asymptomatic.

Discussion

Acute transverse myelitis is characterized by an acute inflammatory process of the spinal cord that can be classified into various etiologically distinct groups. Myelitis with a suspected autoimmune basis is the most common form of ATM that usually occurs as a post- or para-infectious condition, while viral infections are responsible for approximately 25–40% of these cases. Respiratory and intestinal infections are notable potential triggers of ATM, but some post-vaccinal cases have also been reported (Zhu et al. 2020; Guan et al. 2019; Lu et al. 2020).

The clinical picture of ATM includes acute partial or complete motor, sensory, and autonomic spinal cord dysfunction. In a few patients, however, the disease has an ascending course with the risk of asphyxia when upper cervical segments (C3-C5) are involved.

A plausible explanation for the post- or para-infectious or post-vaccinal ATM is that the immunologic process that targets the infectious organism also attacks the central and peripheral nervous systems. A subsequent viral inflammatory process could result in neuronal death or spinal tract lesions. Moreover, a recent study showed that SARS-CoV-2 could enter human cells through ACE2 receptors. Intriguingly, ACE2 receptors are also expressed on the membrane of spinal cord neurons, suggesting that SARS-CoV-2 might be implicated in acute myelitis by the ACE2 receptors (Zhao et al. 2020).

Differential diagnoses of evolving myelopathy are various (Table 2), and viral myelitis can be a challenging diagnosis or, in some cases, the diagnosis of exclusion. Initially, compressive etiologies should be excluded. Also, clinical features, laboratory studies (especially CSF), and imaging findings provide useful information for neurological conditions (Kaplin et al. 2005).

Treatment of ATM is still controversial and should be tailored to the individual patient. The efficacy of antivirals, high doses of IV methylprednisolone, and IVIg in viral immune-mediated neurological disorders, namely ATM, have been reported in the literature (Kaplin et al. 2005).

In this paper, we reported a complicated case of early-onset ATM following a SARS-CoV-2 respiratory infection associated with several diagnostic, therapeutic, and rehabilitative challenges. We only found one study reporting post-infectious acute myelitis as a possible COVID-19 complication (Zhao et al. 2020). Because of the potentially grave and poor neurologic outcomes, sharing the experiences of these patients is vital. We suggest that SARS-CoV-2 can produce different multi-systemic involvements via immune-mediated processes that might be the culprit when a patient presents with acute onset of neurological manifestations, especially after microbial infections or vaccinations (Zhao et al. 2020; Karakonstantis et al. 2017).