What are the next steps for a patient with a 3-week history of cough, severe lower back pain, and right arm weakness that started 7 days after taking praziquantel (an antiparasitic medication)?

Urgent Neuroimaging and Neurocysticercosis Evaluation Required

This patient requires immediate MRI of the brain and entire spine with contrast to rule out neurocysticercosis or spinal cord involvement, as praziquantel can trigger severe inflammatory reactions in patients with undiagnosed CNS parasitic disease, and the combination of back pain with arm weakness 7 days post-treatment strongly suggests spinal cord pathology. 1

Critical Diagnostic Considerations

The timing of symptom onset—7 days after praziquantel—coincides precisely with the expected inflammatory response from dying parasites, which occurs between days 2-5 post-treatment and peaks around day 7. 2 This patient likely had undiagnosed neurocysticercosis or spinal neurocysticercosis before taking praziquantel, and the drug triggered an inflammatory cascade as the parasites died. 1

Why This Is a Neurological Emergency

• Praziquantel is contraindicated in Taenia solium infection without prior neuroimaging because it can precipitate cerebral edema, seizures, or death if brain or spinal cysts are present. 1
• Spinal neurocysticercosis presents with back pain, radicular symptoms, and limb weakness due to cord compression or arachnoiditis—exactly matching this patient's presentation. 1
• The incubation period for neurocysticercosis averages 3.5 years but can exceed 10 years, meaning patients may have asymptomatic cysts that become symptomatic only after praziquantel triggers inflammation. 1
• Worms die between days 2-5 after praziquantel, causing predictable inflammatory exacerbation during this period. 2 At day 7, this patient is in the peak inflammatory phase.

Immediate Diagnostic Workup (Within Hours)

Neuroimaging (Priority #1)

• MRI brain and cervical/thoracic/lumbar spine with and without gadolinium contrast to evaluate for neurocysticercosis, spinal cord lesions, cord compression, and other structural abnormalities. 1
• CT is inadequate—MRI is mandatory for detecting cysticerci and spinal cord pathology. 1

Laboratory Studies

• Complete blood count with manual differential specifically requesting eosinophil count (>10% suggests parasitic CNS infection). 1
• Serum IgE levels (elevated in many helminth infections). 3
• Strongyloides serology before any corticosteroid use to prevent hyperinfection syndrome. 3, 1

Lumbar Puncture (Only After Imaging Rules Out Mass Effect)

• CSF analysis with manual cell count and cytospin specifically requesting eosinophil differential (>10% suggests eosinophilic meningitis). 1
• Do not perform LP until imaging excludes mass lesions or elevated intracranial pressure. 1

Immediate Management Algorithm

If Neurocysticercosis or Spinal Cord Involvement Confirmed

1. Do NOT give additional praziquantel—the damage is already done and more drug will worsen inflammation. 1

2. Initiate high-dose corticosteroids immediately:

   • Prednisolone 60 mg daily for 14 days, then taper according to clinical response. 1
   • Use prednisolone, NOT dexamethasone—dexamethasone significantly reduces praziquantel levels through hepatic metabolism and may have contributed to this problem if used concurrently. 3, 1, 2

3. Gastric protection with proton pump inhibitor during steroid therapy. 1

4. Monitor blood glucose closely during high-dose steroid therapy. 1

5. Neurosurgical consultation if spinal cord compression is present—surgical decompression may be required urgently. 1

Critical Safety Check Before Steroids

• Exclude strongyloidiasis before continuing corticosteroids to prevent hyperinfection syndrome, which is fatal. 3, 1 Send Strongyloides serology immediately and consider empiric ivermectin 200 mcg/kg if high clinical suspicion and steroids cannot be delayed. 3

Alternative Diagnoses to Consider

While neurocysticercosis is most likely given the temporal relationship to praziquantel, also consider:

• Paragonimiasis (lung fluke)—can cause cough, CNS involvement with back pain and weakness, though typically presents with "chocolate" hemoptysis. 3
• Schistosomiasis with spinal cord involvement (neuroschistosomiasis)—can present with back pain and limb weakness, though unusual as a complication of treatment. 1, 4
• Angiostrongylus cantonensis (eosinophilic meningitis)—would expect peripheral eosinophilia. 1

However, the 7-day post-praziquantel timing makes inflammatory response to dying parasites the most likely mechanism. 2

Critical Pitfalls to Avoid

• Never assume back pain and arm weakness are unrelated—cervical pathology causes arm symptoms, not lumbar pathology. This suggests cervical or upper thoracic spinal cord involvement. 1
• Delaying imaging is dangerous—this is a neurological emergency until proven otherwise. 1
• Do not use serology to assess treatment success—antibodies remain positive for years after successful parasite eradication. 4, 2
• Ivermectin has no role in CNS parasitic infections—it does not achieve adequate CSF concentrations. 1
• Symptom exacerbation during days 2-7 represents expected worm death, not treatment failure—but requires aggressive management with corticosteroids. 2

Regarding the 3-Week Cough

The cough predates praziquantel by 2 weeks and may represent:

• Paragonimiasis (lung fluke causing chronic cough, pleuritic pain). 3
• Pulmonary schistosomiasis (acute Katayama syndrome with cough, though typically occurs 2-8 weeks after water exposure). 4
• Loeffler's syndrome (larval migration through lungs causing cough, wheeze, eosinophilia). 3

However, the neurological symptoms are the immediate priority and require urgent evaluation before addressing the pulmonary symptoms. 1