A spinal cord infection is a rare but serious condition in which bacteria, fungi, or viruses infect the spinal cord or the structures around it, such as the vertebrae (bones of the spine), discs between the vertebrae, or the epidural space (the area around the spinal cord). These infections can cause inflammation, pus-filled pockets (abscesses), and pressure on the spinal cord, which may lead to widespread illness and nerve problems. One common type, called a spinal epidural abscess, occurs in about 0.2–2 people per 10,000 hospital admissions each year. People with diabetes, weakened immune systems, a history of intravenous drug use, or recent spinal procedures are at higher risk.
Symptoms often start gradually. Persistent back pain that gets worse over time, especially at night, is common. Fever, chills, and stiffness may also appear. If the infection affects the neck (cervical spine), it can cause neck pain and rigidity. Other signs include fatigue, night sweats, poor appetite, and unintended weight loss. In severe cases, the infection can damage nerves, causing weakness, numbness, tingling, or loss of control over bowel and bladder functions. Without treatment, these problems can become permanent.
Most spinal cord infections occur when bacteria travel through the bloodstream from another part of the body, such as the skin, urinary tract, or lungs. They can also result from direct introduction during spinal injury, surgery, or medical procedures like lumbar punctures, or from nearby infected tissues spreading the infection. Staphylococcus aureus, including drug-resistant strains (MRSA), is the most common cause, responsible for 60–70% of cases. Other bacteria like Escherichia coli, Streptococcus, and Pseudomonas aeruginosa can also cause infection. Fungal infections, such as Candida or Aspergillus, are less common and usually affect people with weakened immune systems. Viral infections of the spinal cord, such as those caused by herpes zoster or enteroviruses, are rare.
Treatment usually involves long courses of intravenous antibiotics. Examples include vancomycin for MRSA, ceftriaxone or cefotaxime for certain Gram-negative bacteria, and fluconazole or amphotericin B for fungal infections. Surgery may be needed if there is pressure on the spinal cord, an abscess, or spine instability. Common surgical procedures include laminectomy (removing part of a vertebra to relieve pressure) and debridement (removing infected tissue).
Prevention focuses on lowering risk and avoiding exposure to infection. Measures include promptly treating other infections in the body, following strict sterile techniques during spinal procedures, managing conditions like diabetes or immune deficiencies carefully, and avoiding intravenous drug use. Vaccinations against bacteria such as Streptococcus pneumoniae and Haemophilus influenzae may also help reduce the risk of infections spreading to the spine.
Definition and Classification
Spinal cord infections are inflammatory conditions caused by infectious agents that affect the spinal cord itself, its protective coverings (meninges), or the surrounding epidural space. The term encompasses a range of conditions, including myelitis, which involves direct infection of the spinal cord tissue (parenchyma), and epidural abscesses, which are collections of pus in the space outside the dura mater, the tough membrane surrounding the spinal cord. These infections can lead to significant neurological impairment if not promptly diagnosed and treated.
Classification of spinal cord infections is primarily based on the type of pathogen involved:
- Bacterial infections, which are the most common, particularly in epidural abscesses. Staphylococcus aureus, including methicillin-resistant strains (MRSA), accounts for approximately 60–70% of bacterial cases. Other bacterial causes include Escherichia coli, Streptococcus species, and Pseudomonas aeruginosa.
- Viral infections, such as those caused by herpes simplex virus, varicella-zoster virus, and enteroviruses, primarily lead to inflammation of the spinal cord without abscess formation.
- Fungal infections, including Cryptococcus, Candida, and Aspergillus species, are less common and typically affect individuals with weakened immune systems, such as those with HIV/AIDS or undergoing chemotherapy.
- Parasitic infections, though rare, may occur in endemic regions or in immunocompromised individuals. Examples include Schistosoma species, which can invade the spinal cord, causing myelopathy.
The location (cervical, thoracic, or lumbar spine) and the nature (diffuse inflammation versus localized abscess) of the infection influence clinical manifestations and guide therapeutic strategies.
Epidemiology and Prevalence
Spinal cord infections are relatively rare but carry significant morbidity and mortality if untreated. The incidence of spinal epidural abscess, one of the most frequently studied forms, is estimated at 0.2–2 cases per 10,000 hospital admissions annually, with increasing prevalence in patients with diabetes, intravenous drug use, chronic kidney disease, or immunosuppression. Studies suggest that the incidence has risen over the past decades due to aging populations, greater use of spinal instrumentation, and improved diagnostic imaging.
Bacterial infections account for the majority of spinal cord infections. Staphylococcus aureus is the leading pathogen, responsible for up to 70% of cases, followed by Gram-negative bacteria such as E. coli and Pseudomonas aeruginosa. Fungal infections, while uncommon, constitute approximately 1–5% of spinal infections in hospital settings, primarily in immunocompromised patients. Viral causes are less common and more frequently identified in pediatric populations. The mortality rate for untreated spinal epidural abscess can exceed 20%, and permanent neurological deficits occur in 30–50% of cases.
Pathophysiology
The pathophysiology of spinal cord infections involves complex interactions between pathogens and host responses. The infection may reach the spinal cord through hematogenous spread, in which bacteria or fungi enter the bloodstream from another infected site, such as the skin, urinary tract, or lungs, and localize in the spine. Alternatively, infections can arise via direct extension from nearby tissues, including vertebral osteomyelitis, soft tissue infections, or following spinal surgery or invasive procedures like lumbar puncture.
Once pathogens reach spinal tissues, they trigger an inflammatory response, increasing vascular permeability and leading to spinal cord edema (swelling). This inflammation can interfere with nerve conduction, resulting in neurological symptoms such as weakness, numbness, or sensory deficits. In some cases, the infection causes tissue necrosis, abscess formation, or vascular thrombosis, which further compromises spinal cord perfusion and can exacerbate injury.
The immune response is a double-edged sword. While it is essential for controlling pathogen growth, excessive or prolonged inflammation can contribute to secondary spinal cord injury. Cytokines and immune cells released during infection may increase pressure within the spinal canal and promote demyelination or axonal injury. Chronic inflammation may also lead to fibrosis and long-term neurological deficits, even after the infection has been cleared.
Causes and Risk Factors
Spinal cord infections arise from various microorganisms that invade the spinal tissues. Certain medical conditions and lifestyles increase the likelihood of these infections developing.
Bacterial Infections
Bacterial infections are the most common cause of spinal cord infections and can arise through direct invasion of spinal tissues or hematogenous spread, in which bacteria travel through the bloodstream from distant sites. Staphylococcus aureus is the leading pathogen, responsible for the majority of spinal epidural abscesses. Other bacteria implicated include Escherichia coli, Pseudomonas aeruginosa, Streptococcus species, and Mycobacterium tuberculosis, which can cause spinal tuberculosis (Pott disease).
Bacterial infections frequently develop after trauma, spinal surgery, or invasive medical procedures such as lumbar punctures or epidural catheter placement. Individuals with compromised immune systems, including patients with HIV/AIDS, cancer, or those taking immunosuppressive medications, are particularly vulnerable. The bacterial infection induces inflammation, leading to pus accumulation (abscess formation), tissue destruction, and swelling, which can compress the spinal cord and result in neurological deficits.
Viral Infections
Viral infections of the spinal cord are less common than bacterial infections but can cause significant morbidity. They include conditions such as transverse myelitis, characterized by inflammation across a segment of the spinal cord, and viral meningitis with spinal involvement. Common viral pathogens include herpes simplex virus (HSV), varicella-zoster virus (VZV), and enteroviruses.
Viruses may reach the spinal cord through the bloodstream or along nerve pathways, where they trigger inflammatory responses that cause swelling and interfere with normal nerve function. Symptoms can include limb weakness, sensory disturbances, and bowel or bladder dysfunction. Viral spinal infections are more likely to affect immunocompromised individuals, including neonates, the elderly, or patients with chronic illnesses.
Fungal Infections
Fungal spinal infections are rare but carry a high risk of serious complications. They primarily affect patients with immunosuppression, such as those with HIV/AIDS, organ transplant recipients, or individuals undergoing chemotherapy. Common fungal pathogens include Candida, Aspergillus, and Cryptococcus species.
Fungi can reach the spine either through the bloodstream or by direct extension from nearby infected tissues, such as the lungs or vertebrae. These infections often result in the formation of granulomas, localized collections of immune cells and abscesses, which can compress the spinal cord and lead to neurological impairment. Treatment usually requires long-term antifungal therapy and, in severe cases, surgical intervention to relieve pressure on neural structures.
Predisposing Conditions
Several conditions and behaviors increase the likelihood of spinal cord infections. Immunosuppression, whether due to diseases such as HIV/AIDS, medications like corticosteroids, or malnutrition, reduces the body’s ability to fight infections. Chronic illnesses such as diabetes mellitus impair blood circulation and immune function, further increasing vulnerability.
Intravenous drug use introduces pathogens directly into the bloodstream, creating a direct route for bacteria or fungi to reach the spinal cord. Similarly, spinal trauma or surgical procedures can breach protective barriers, allowing microorganisms to enter and infect the spinal tissues. Advanced age, alcoholism, and chronic kidney disease have also been identified as risk factors for developing severe spinal cord infections.
Clinical Manifestations
Spinal cord infections present with a range of symptoms that reflect direct damage to neural structures and systemic inflammation. These symptoms can vary based on the pathogen involved, infection location, and disease stage.
Neurological Symptoms
Neurological involvement is a hallmark of spinal cord infections. Patients commonly report localized back pain that may be sharp, burning, or throbbing, and often worsens at night or with movement. The pain may radiate along dermatomes corresponding to the affected spinal segment. Sensory disturbances, including numbness, tingling, or loss of sensation below the level of infection, are frequently observed.
Motor deficits typically appear as weakness or paralysis in the limbs, corresponding to the spinal segment involved. For example, cervical infections may cause weakness in the arms and legs, while lumbar infections primarily affect lower limb function. Reflex changes, such as hyperreflexia (exaggerated reflexes) or hyporeflexia/areflexia (reduced or absent reflexes), provide additional clinical clues to spinal cord involvement.
Autonomic dysfunction may also occur, leading to bladder and bowel disturbances, including urinary retention, incontinence, or constipation. In severe or chronic cases, patients may develop spasticity, characterized by increased muscle tone, or muscle atrophy due to prolonged disuse or nerve damage. Patients with extensive spinal cord involvement may experience paraplegia or quadriplegia, depending on the level of infection.
Systemic Signs
Systemic manifestations reflect the body’s immune response to infection. Fever is a common presenting feature and may be persistent or intermittent. Patients often experience fatigue, malaise, night sweats, and unintended weight loss, reflecting the metabolic and inflammatory burden of infection. Laboratory studies frequently show elevated white blood cell counts and increased inflammatory markers, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).
In bacterial infections, systemic signs can be severe. Sepsis, characterized by hypotension, tachycardia, and multi-organ dysfunction, may develop in advanced cases, necessitating urgent medical intervention. Fungal or viral infections often produce subtler systemic signs, with less pronounced fever or inflammatory response, which can delay diagnosis.
Disease Progression
Early-stage infection mainly causes localized pain and mild neurological impairment. Without treatment, symptoms progress to severe neurological deficits, including extensive paralysis and autonomic dysfunction.
Cord abscess formation or necrosis can occur, worsening outcomes. Chronic infection may lead to scarring and permanent spinal cord damage. Rapid diagnosis and treatment are crucial to prevent irreversible neurological impairment.
Diagnostic Approaches
Diagnosing spinal cord infections requires a combination of clinical evaluation, laboratory data, and imaging studies. Each method provides essential information to confirm infection and determine its extent.
Physical Examination
The physical examination focuses on neurological assessment. Physicians check for motor weakness, sensory deficits, and reflex changes that may indicate spinal cord involvement.
Pain localization is critical, often correlating to the affected vertebral level. Signs of meningeal irritation or systemic infection, like fever, are also evaluated.
A detailed patient history complements these findings, including onset, progression, and associated symptoms such as bladder or bowel dysfunction. This helps narrow the differential diagnosis and prioritize testing.
Laboratory Testing
Laboratory tests aim to identify the infectious agent and assess systemic involvement. Blood cultures are essential for detecting bacteremia or fungemia.
Cerebrospinal fluid (CSF) analysis via lumbar puncture provides direct evidence. Key tests include cell count, protein, glucose levels, Gram stain, and culture. Polymerase chain reaction (PCR) can detect specific pathogens faster.
Inflammatory markers like erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are useful but nonspecific. Serologic tests may assist in diagnosing certain viral or fungal infections.
Imaging Techniques
Magnetic resonance imaging (MRI) is the preferred diagnostic imaging modality. It offers high-resolution views of soft tissue, spinal cord, and surrounding structures.
MRI can identify abscesses, edema, and cord compression. Contrast enhancement improves detection of infectious lesions.
Computed tomography (CT) is helpful when MRI is contraindicated. CT myelography may be an alternative to evaluate spinal cord involvement indirectly.
Radiographs have limited utility but may show vertebral body destruction in advanced cases.
Management and Treatment Strategies
Treatment of spinal cord infections requires precise interventions tailored to the pathogen, severity, and complications.
Antimicrobial Therapy
Antimicrobial therapy remains the cornerstone of treatment for spinal cord infections. The selection of antibiotics or antivirals is guided by microbiological identification, local resistance patterns, and the infection’s anatomic location. Empirical therapy is typically initiated while awaiting culture results and later refined once the pathogen is confirmed.
For bacterial infections, broad-spectrum intravenous antibiotics are often started, such as vancomycin combined with ceftriaxone or cefotaxime, to cover both Gram-positive and Gram-negative organisms, including Staphylococcus aureus and Escherichia coli. In cases of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin or linezolid is preferred. For anaerobic or polymicrobial infections, metronidazole may be added to the regimen.
The duration of antimicrobial therapy typically extends from 4 to 6 weeks, depending on the severity of infection and the presence of abscesses. However, in cases involving osteomyelitis, epidural abscess, or slow clinical response, treatment may be prolonged to 8 weeks or more. When fungal infections (e.g., Candida or Aspergillus) are implicated, antifungal agents such as amphotericin B or voriconazole are indicated, often for several months.
For viral etiologies, management is more supportive, though acyclovir remains the drug of choice for herpes simplex virus (HSV) or varicella-zoster virus (VZV) infections. In HIV-related spinal infections, combination antiretroviral therapy (cART) is essential to control viral replication and prevent opportunistic infections.
Surgical Intervention
Surgical management is warranted in selected cases where infection leads to spinal cord compression, abscess formation, vertebral instability, or failure of medical therapy. The decision to operate is guided by imaging modalities such as MRI, which remains the gold standard for detecting abscesses, osteomyelitis, and epidural involvement.
Common procedures include decompression laminectomy, abscess drainage, and debridement of necrotic or infected tissue. In cases with extensive vertebral damage, spinal stabilization using instrumentation may be necessary to preserve structural integrity. The primary goal of surgery is to relieve pressure on the spinal cord, eradicate the infectious source, and create conditions favorable for healing.
Supportive Care
Supportive care forms an essential part of the overall treatment strategy and focuses on symptom management, rehabilitation, and prevention of secondary complications.
Pain management is achieved using a stepwise approach starting with non-opioid analgesics and escalating to opioids when necessary. Physical and occupational therapy play vital roles in maintaining joint mobility, muscle strength, and functional independence. For patients with motor deficits, assistive devices such as braces or walkers may aid in mobility and reduce the risk of falls.
Autonomic dysfunctions, including bladder or bowel incontinence, require targeted management such as intermittent catheterization, bladder retraining, or bowel programs. Nutritional support, emphasizing adequate protein and caloric intake, accelerates tissue repair and immune recovery. Preventive measures, including frequent repositioning and use of pressure-relief mattresses, help avoid pressure ulcers in immobilized patients.
In severe cases, particularly those with respiratory compromise or hemodynamic instability, patients may require intensive care unit (ICU) monitoring. Here, respiratory support, autonomic regulation, and close neurological monitoring are vital for preventing further deterioration.
Finally, long-term follow-up is essential to assess residual deficits, detect late complications such as spinal deformity or chronic infection, and provide psychosocial support.
Complications of Spinal Cord Infections
Spinal cord infections can lead to serious medical issues affecting motor, sensory, and structural functions. These complications often require long-term management and impact quality of life significantly.
Neurological Deficits
Neurological deficits represent the most immediate and devastating consequence of spinal cord infections. They result from direct microbial invasion, inflammatory edema, or ischemic injury caused by compression of spinal vasculature. The severity of deficits depends on the infection’s location, extent of cord involvement, and timing of intervention.
Patients commonly present with motor weakness, loss of sensation, or paralysis below the level of the infection. The pattern can vary, paraparesis or paraplegia in thoracic involvement and quadriparesis or quadriplegia in cervical lesions. Incomplete lesions may allow partial recovery, while complete spinal cord involvement often leads to permanent deficits.
Inflammation or abscess formation can also disrupt ascending sensory tracts (spinothalamic and dorsal column pathways), leading to loss of proprioception, vibration sense, or fine touch. Patients may report numbness, tingling, or paresthesias that can progress to complete sensory loss if untreated.
Equally significant is autonomic dysfunction, which affects involuntary functions such as bladder, bowel, and sexual activity. Damage to the intermediolateral cell columns or descending autonomic fibers may lead to urinary retention, incontinence, constipation, or impotence.
Chronic Pain Syndromes
Chronic pain is another frequent and debilitating complication following spinal cord infections. It often manifests as neuropathic pain, which arises from injury to the spinal cord’s sensory pathways or nerve roots during the infectious process. Unlike nociceptive pain, which results from tissue damage, neuropathic pain originates from abnormal signaling within damaged neural circuits.
Patients may describe sharp, burning, stabbing, or electric shock–like sensations, frequently localized to dermatomes below the level of spinal involvement. Pain intensity often fluctuates but may become persistent and resistant to standard analgesics, posing challenges for management. This type of pain is commonly associated with infections such as epidural abscesses or viral myelitis (e.g., herpes zoster).
Because conventional painkillers (e.g., opioids or NSAIDs) provide limited relief, specialized pharmacologic approaches are necessary. These include anticonvulsants such as gabapentin or pregabalin, and antidepressants like amitriptyline or duloxetine, which modulate neuropathic pain pathways. Non-pharmacological therapies, such as transcutaneous electrical nerve stimulation (TENS), spinal cord stimulation, cognitive behavioral therapy (CBT), and mindfulness-based interventions, can provide additional benefit.
Chronic pain can persist long after the infection has resolved, contributing to sleep disturbances, anxiety, depression, and reduced quality of life.
Spinal Deformities
Spinal deformities are structural complications that develop as a result of infection-related destruction of the vertebral bodies, intervertebral discs, and supporting ligaments. Conditions such as vertebral osteomyelitis or spondylodiscitis can cause collapse of the vertebral column, leading to angular deformities like kyphosis (forward curvature) or scoliosis (lateral curvature).
These deformities not only cause chronic mechanical back pain but can also lead to progressive spinal instability and secondary compression of neural elements, exacerbating neurological symptoms. In severe cases, deformities compromise posture, gait, and pulmonary function, particularly when thoracic segments are involved.
The risk of deformity is higher in infections caused by tuberculosis (Pott’s disease), where slow, progressive bone destruction occurs over months.
Other Potential Complications
- Beyond the primary neurological and structural consequences, spinal cord infections can precipitate a range of secondary systemic and rehabilitative complications:
- Sepsis and systemic spread: If pathogens enter the bloodstream, they can lead to sepsis, endocarditis, or multiorgan dysfunction, especially in immunocompromised patients.
- Pressure ulcers and muscle atrophy: Prolonged immobility contributes to pressure injuries and muscle wasting, requiring diligent nursing care and physiotherapy.
- Deep vein thrombosis (DVT) and pulmonary embolism (PE): Reduced mobility increases the risk of thromboembolic events, which necessitate prophylactic anticoagulation in high-risk individuals.
Prevention and Risk Reduction
Effective prevention of spinal cord infections involves targeted measures to reduce exposure risks, control infection sources, and identify early symptoms.
Vaccination
Vaccination remains one of the most effective strategies for preventing infections that can lead to spinal cord involvement. Immunization against key pathogens such as Haemophilus influenzae type b (Hib), Neisseria meningitidis, and Streptococcus pneumoniae has dramatically reduced the global incidence of meningitis, epidural abscesses, and other infections that may spread to the spinal cord. These vaccines are particularly important for infants, elderly adults, and immunocompromised patients, whose immune defenses are less robust.
Additionally, the varicella-zoster vaccine helps prevent reactivation of the virus responsible for shingles, which can occasionally lead to herpes zoster myelitis, a form of viral spinal cord inflammation. Likewise, the influenza vaccine indirectly protects high-risk groups by reducing the incidence of secondary bacterial infections that can seed the central nervous system.
Infection Control Measures
In healthcare environments, strict adherence to infection prevention and control (IPC) protocols is essential to reduce iatrogenic spinal infections, particularly after invasive procedures. Proper hand hygiene remains the single most effective measure for preventing hospital-acquired infections. Healthcare workers should wash hands before and after every patient interaction, even when gloves are used.
Aseptic technique is mandatory during procedures involving the spinal column, such as lumbar punctures, epidural anesthesia, spinal taps, or surgery, to prevent introduction of pathogens into sterile spaces. This includes thorough sterilization of medical instruments, use of personal protective equipment (PPE) such as sterile gloves, masks, and gowns, and maintaining a clean procedural environment. Operating rooms and intensive care units should implement regular air filtration and surface disinfection to reduce airborne and contact transmission.
For patients undergoing spinal surgeries or implants, prophylactic antibiotics may be administered preoperatively to prevent postoperative infections. Post-surgical wound care, including regular cleaning, dressing changes, and monitoring for signs of infection (e.g., redness, discharge, or fever), is equally critical.
Early Detection
Early recognition of spinal cord infection symptoms, such as fever, localized back pain, neurological deficits, or altered reflexes, is critical to limit progression.
Prognosis and Long-Term Outcomes
The prognosis of spinal cord infections varies widely depending on the severity of the infection and the timeliness of treatment. Long-term effects can range from full recovery to permanent neurological deficits.
Recovery Factors
Recovery largely depends on the type of pathogen, the extent of spinal cord damage, and how quickly antimicrobial therapy begins. Bacterial infections like spinal epidural abscesses typically require urgent intervention to prevent permanent paralysis.
Patient age and preexisting health conditions also influence outcomes. Younger patients with fewer comorbidities generally have better recovery rates. Early diagnosis and surgical drainage, when needed, significantly improve functional restoration.
Delays in treatment may lead to irreversible damage due to inflammatory responses and tissue necrosis. The presence of complications such as abscess formation and spinal instability can worsen prognosis.
Rehabilitation Needs
Rehabilitation focuses on regaining motor function, sensory capabilities, and independence. Physical therapy aims to strengthen weakened muscles and improve mobility.
Occupational therapy assists with daily living activities, emphasizing adaptations for sensory or motor deficits that remain after infection resolution. Pain management and psychological support are often necessary due to chronic discomfort and emotional impact.
Long-term rehabilitation may involve assistive devices like braces or wheelchairs for patients with severe neurological impairment. Periodic neurological assessments help guide rehabilitation adjustments and monitor for secondary complications.