What are the potential causes and recommended management for a patient presenting with cough, severe lower back pain, and right arm weakness 9 days after taking praziquantel (an antiparasitic medication)?

Urgent Neurological Emergency: Immediate Imaging Required for Suspected Neurocysticercosis

This patient requires immediate MRI of the brain and entire spine with contrast to rule out neurocysticercosis or spinal neuroschistosomiasis—praziquantel can trigger life-threatening inflammation in undiagnosed CNS parasitic disease, and the 9-day timeline coincides with peak worm death and inflammatory response. 1, 2

Critical Pathophysiology

The timing is highly concerning because worms begin dying between days 2-5 after praziquantel administration, triggering an inflammatory response that causes symptom exacerbation precisely during this 9-day window. 2 This patient's presentation of cough, severe lower back pain, and right arm weakness 9 days post-treatment suggests either:

• Neurocysticercosis (undiagnosed Taenia solium brain/spinal cysts) that became symptomatic after praziquantel triggered inflammatory response 1
• Spinal neuroschistosomiasis causing cord compression or arachnoiditis, presenting with back pain and limb weakness 1
• Acute schistosomiasis (Katayama syndrome) with neurological complications, though this typically occurs 2-8 weeks after water exposure, not after treatment 3

Immediate Diagnostic Workup

Neuroimaging (Highest Priority)

• MRI brain and cervical/thoracic/lumbar spine with and without gadolinium contrast to evaluate for neurocysticercosis cysts, spinal cord lesions, cord compression, and structural abnormalities 1
• This is a neurological emergency until proven otherwise—do not delay imaging 1

Laboratory Studies

• Complete blood count with differential specifically requesting eosinophil count (>10% suggests parasitic CNS infection) 1
• Serum IgE levels and Strongyloides serology before any corticosteroid administration to prevent hyperinfection syndrome 1, 3
• CSF analysis (only if safe after imaging) with manual cell count and cytospin requesting eosinophil differential 1

Management Algorithm Based on Imaging Results

If Neurocysticercosis Confirmed

• Do NOT give additional praziquantel 1
• Initiate high-dose prednisolone 60 mg daily for 14 days, then taper according to clinical response 1
• Use prednisolone specifically, NOT dexamethasone, as dexamethasone significantly reduces praziquantel levels through increased hepatic metabolism 3, 2
• Provide gastric protection with proton pump inhibitors and monitor blood glucose 1

If Spinal Neuroschistosomiasis Confirmed

• Praziquantel 40 mg/kg twice daily for 5 days for CNS involvement 3
• Combine with prednisolone (not dexamethasone) 4 mg four times daily, reducing after 7 days, for total 2-6 weeks 3
• In acute neuroschistosomiasis, corticosteroids should be given first, before anthelmintic therapy 3

If Acute Schistosomiasis (Katayama Syndrome)

• Prednisolone 30 mg daily for 5 days to reduce symptom duration 3
• Repeat praziquantel dose at 6-8 weeks after initial dose, as immature schistosomules are relatively resistant to initial treatment 3, 2
• Praziquantel should be administered after the acute inflammatory phase resolves 3

Critical Pitfalls to Avoid

• Never treat T. solium with praziquantel without neuroimaging first—this can precipitate cerebral edema, seizures, or death 1
• Do not assume back pain and arm weakness are related—cervical pathology causes arm symptoms, not lumbar pathology; this suggests multilevel spinal involvement 1
• Exclude strongyloidiasis before starting corticosteroids to prevent hyperinfection syndrome 3, 1
• Do not use dexamethasone if steroids are needed, as it significantly reduces praziquantel levels; use prednisolone instead 3, 1, 2
• Recognize that symptom exacerbation during days 2-5 post-treatment represents expected worm death, not treatment failure, but neurological symptoms at day 9 require urgent evaluation 2

Alternative Diagnoses to Consider

• Paragonimiasis (lung fluke) can cause cough and CNS involvement with back pain and weakness, though typically presents with "chocolate" hemoptysis 1
• Angiostrongylus cantonensis (eosinophilic meningitis) can cause neurological symptoms, though peripheral eosinophilia would be expected 1
• Loeffler's syndrome (larval migration through lungs) causing cough, wheeze, and eosinophilia 1

Why This Cannot Wait

The 9-day timeline places this patient in the critical window where dying parasites trigger maximal inflammatory response. 2 If undiagnosed CNS cysts are present, the inflammatory response to dying larvae in brain or spinal cord tissue can cause life-threatening edema, seizures, or permanent neurological damage. 1, 2 Immediate imaging and appropriate corticosteroid therapy can prevent catastrophic outcomes.