A shunt infection is a serious complication that can occur after a shunt placement surgery. Shunts are medical devices implanted in the brain to drain excess cerebrospinal fluid and relieve pressure on the brain. While fever is a common symptom of shunt infection, it is possible to have an infection without a fever. Some key points about shunt infections without fever include:
It is uncommon but possible
Most patients with a shunt infection will develop a fever, usually ranging from 101-104°F. However, in some cases, patients can have subtle or atypical symptoms without a high fever. Low grade fevers, fever that comes and goes, or no fever at all are possible.
Other symptoms may still be present
Even without a significant fever, other signs and symptoms of a shunt infection may be noticeable. These can include:
- Redness, swelling, or tenderness along the shunt tract
- Headaches or change in headache pattern
- Nausea/vomiting
- Irritability or change in mental status
- Stiff neck
- Sensitivity to light
- Seizures
Diagnostic testing is important
Diagnosing a shunt infection without classic fever symptoms requires a high degree of clinical suspicion. Doctors may use blood tests looking for elevated white blood cell count, erythrocyte sedimentation rate (ESR), or C-reactive protein (CRP). Imaging such as CT scan or shunt X-ray can check for abnormalities. A sample of cerebrospinal fluid may be taken to analyze for infection.
Prompt treatment is still needed
Even without a high fever, a shunt infection can still cause serious complications if left untreated. These include shunt malfunction, permanent neurological damage, or life-threatening sepsis. So prompt antibiotic treatment and likely shunt replacement surgery are still required.
What causes a shunt infection without fever?
There are a few possible reasons why someone could develop a shunt infection without the telltale sign of high fever:
- Partially treated infection – Antibiotics may have been started at onset of symptoms, masking fever.
- Local infection – Infection is contained around the shunt area and has not spread to the rest of the body or caused a systemic immune response.
- Compromised immune system – Certain medical conditions, like cancer treatment or autoimmune disease, may blunt normal fever response.
- Specific pathogens – Low virulent organisms, like Propionibacterium acnes, cause subtle symptoms.
- Individual variation – Every patient’s body responds differently to infection.
The most common cause is likely just a variation in symptom presentation between different people with shunt infections. However, sometimes determining an underlying reason for lack of fever can help guide treatment in atypical cases.
How common are shunt infections without fevers?
Shunt infections overall occur in 5-15% of shunt procedures. Of these infections, the number presenting without fever is relatively small. Some statistics on prevalence include:
- One study found 7% of shunt infections had no fever at initial presentation.
- Another study found the number to be closer to 2-4% of all shunt infection cases.
- Low grade or intermittent fever may be more common than complete lack of fever.
So while it does sometimes occur, the large majority of shunt infections will have some degree of elevated temperature. Lack of any fever is considered atypical and requires thorough evaluation to rule out other potential causes of symptoms.
Risk factors
Certain conditions or factors can increase risk that someone might develop a shunt infection without the classic fever response:
- Recent antibiotics – Can mask fever before infection is under control.
- Premature infants – Immature immune systems may mount smaller fever response.
- Young children – Younger than 6 months old less capable of fever production.
- Immunocompromised – Chronic illness, chemotherapy, steroid use can impair febrile response.
- History of shunt infections – Scarring around shunt can prevent fever spread.
- Shunt location – Ventriculoperitoneal vs ventriculoatrial shunts may change fever risk.
Being aware of these risk factors can help raise suspicion for shunt infection even without fever being present. Prompt diagnosis then allows for earlier treatment in these higher risk groups.
Diagnosis
Diagnosing shunt infection without the usual fever requires a combination of clinical suspicion and confirmatory testing:
Physical exam
The first step is a thorough physical exam checking for:
- Swelling, redness, or tenderness along shunt tract
- Nuchal rigidity (stiff neck)
- Altered mental status or neurological deficits
- Bulging fontanelle in infants
Lab tests
Helpful lab tests include:
- Complete blood count (CBC) looking for elevated white blood cells
- Blood cultures to identify infectious organism
- C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) to assess inflammation
- Cerebrospinal fluid (CSF) analysis for cell count, glucose, protein, gram stain, and culture
Imaging
Radiographic imaging techniques such as:
- CT scan to look for signs of infection like edema or abscess
- X-ray to check shunt position and identify breaks or discontinuities
- Ultrasound to look for fluid build up
Nuclear scanning
Specialized scans like gallium scan or leukocyte scanning can sometimes detect shunt infection.
Early suspicion, combining results from various tests, and repeat testing over time is key to diagnosing the often subtle signs of shunt infection without fever.
Treatment
When infection is diagnosed, prompt treatment is crucial even without overt fever:
Antibiotics
Broad spectrum IV antibiotics are started immediately to treat the infection. Typical choices include vancomycin, third generation cephalosporins, or carbapenem. Antibiotics are continued for several weeks.
Shunt removal
In most cases of infection, the shunt will need to be completely removed to clear the infection. External ventricular drainage is placed temporarily while infection resolves.
Shunt replacement
After infection has cleared and CSF cultures are negative, a new shunt can be placed in a different location if still required. Strict sterile technique prevents new infection.
Symptomatic therapies
Supportive treatments like headache management, anticonvulsants for seizures, or antipsychotic medications may also be needed.
Aggressive treatment gives the best chance for full recovery, even if lack of fever means infection is identified late. Close follow up is needed to be sure infection is fully eradicated.
Prognosis and complications
With appropriate treatment, the prognosis for shunt infections without fever is generally good but depends on several factors:
- How quickly infection is recognized and treated
- Extent of infection along shunt tract
- Child’s age, immune function, and overall health
- Specific organism involved
Potential complications if infection persists include:
- Worsening hydrocephalus
- Permanent brain damage or neurological deficits
- Endocarditis, meningitis, brain abscess from bacterial seeding
- Sepsis and death in severe cases
Close monitoring and follow up after treatment is needed to watch for rare complications like delayed repeat infection or shunt failure. Overall outcomes are very good with prompt, aggressive management.
Prevention
Preventing shunt infections in general also lowers risk of atypical infections without fever:
- Meticulous sterile technique during surgery
- Antibiotic impregnated shunt catheters
- Prophylactic antibiotics before and after surgery
- Avoiding shunt overdrainage
- Careful wound care and infection control post-op
Routine CSF shunt tapping and drainage protocols may also help lower infection risk. Despite best efforts, however, infections can still sometimes occur.
Conclusion
While uncommon, shunt infections without fever do occasionally occur and require a high index of suspicion to diagnose. Typical symptoms may be more subtle, but prompt treatment is still needed to avoid serious complications. Combining a thorough history and physical exam with laboratory testing and neuroimaging allows accurate diagnosis. With aggressive antibiotic therapy and removal of infected shunt hardware, outcomes can still be very favorable. Prevention efforts remain key to reducing all types of shunt infections including atypical presentations without fever.