What are the potential causes and recommended actions for a patient experiencing lower back pain and right arm weakness a few days after taking praziquantel (an antiparasitic medication)?

Urgent Neurological Evaluation Required for Possible Neurocysticercosis

This patient requires immediate neuroimaging (MRI brain and spine) and urgent neurology consultation to rule out neurocysticercosis or other CNS parasitic infection before any further treatment, as praziquantel can precipitate life-threatening neurological deterioration if undiagnosed brain or spinal cysts are present. 1, 2

Critical Differential Diagnosis

The combination of lower back pain and right arm weakness following praziquantel administration raises several urgent concerns:

Primary Concern: Neurocysticercosis (Taenia solium)

• Praziquantel is contraindicated in T. solium tapeworm infection without prior neuroimaging, as it can worsen neurological symptoms if brain or spinal cysts are present 1
• The incubation period for neurocysticercosis averages 3.5 years but can exceed 10 years, meaning patients may have asymptomatic cysts that become symptomatic after praziquantel triggers an inflammatory response 3
• Spinal neurocysticercosis can present with back pain, radicular symptoms, and limb weakness due to cord compression or arachnoiditis 3

Alternative Parasitic Causes

• Neuroschistosomiasis affecting the spinal cord can present with back pain and limb weakness, though this typically occurs with S. mansoni or S. haematobium and would be unusual as a complication of treatment 2
• Angiostrongylus cantonensis (eosinophilic meningitis) can cause neurological symptoms, though peripheral eosinophilia would be expected 3

Non-Parasitic Causes

• Acute lower back pain with radicular symptoms (right arm weakness suggests cervical radiculopathy, not lumbar pathology) may be coincidental and unrelated to praziquantel 3
• Praziquantel has very low toxicity and mild side effects, with no documented direct neurotoxicity 4, 5

Immediate Diagnostic Workup

Neuroimaging (Urgent)

• MRI brain and cervical/thoracic spine with and without contrast to evaluate for:
  • Neurocysticercosis (ring-enhancing lesions, calcifications, ventricular involvement)
  • Spinal cord lesions or compression
  • Other structural abnormalities 3

Laboratory Studies

• Complete blood count with differential (look for eosinophilia >10% suggesting parasitic CNS infection) 3
• If lumbar puncture is safe after imaging: CSF analysis with manual cell count and cytospin specifically requesting eosinophil count (>10% differential suggests eosinophilic meningitis) 3
• Serum and CSF serology for cysticercosis if available 3

Clinical History Details

• Exact indication for praziquantel treatment (schistosomiasis, liver flukes, tapeworm?)
• Travel history and potential exposure to T. solium (pork consumption in endemic areas)
• Timeline: Did neurological symptoms begin before, during, or after praziquantel?
• Presence of seizures, headache, or other neurological symptoms 3

Management Algorithm

If Neurocysticercosis Confirmed:

• Do NOT give additional praziquantel 1
• Initiate high-dose corticosteroids: prednisolone 60 mg daily for 14 days, then taper according to clinical response 3
• Monitor blood glucose and provide gastric protection with proton pump inhibitors 3
• Exclude strongyloidiasis before continuing steroids to prevent hyperinfection syndrome 3, 2
• Antiepileptic therapy if seizures present 3
• Neurosurgical consultation for ventricular or spinal involvement 3

If Imaging Negative for Cysticercosis:

• Evaluate for mechanical causes of radiculopathy (cervical disc herniation, spinal stenosis)
• Consider nonpharmacologic therapy for acute back pain: superficial heat, massage, acupuncture, or spinal manipulation 3
• NSAIDs as first-line pharmacologic therapy if needed 3
• Physical therapy and reassurance that most acute episodes resolve within 4 weeks 3

Critical Pitfalls to Avoid

• Never treat T. solium with praziquantel without neuroimaging first, as this is the most dangerous error and 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 3
• Do not use dexamethasone if steroids are needed, as it significantly reduces praziquantel levels and may have been used concurrently; use prednisolone instead 1, 2, 6
• Do not delay imaging—this is a neurological emergency until proven otherwise 3
• Ivermectin has no role in CNS parasitic infections as it does not achieve adequate CSF concentrations 3