A 40-year-old female patient presented to our service with a 5-day history of progressive right-sided low back pain, which radiated over the right buttock into the anterior thigh in an L4 distribution. The pain was nonpositional and exacerbated by coughing. She also complained of new bifrontal headaches, difficulty in concentrating, stool retention, and difficulty in passing urine. Two weeks previously, she had commenced an immunisation against adult tick-borne encephalitis (TBE) by self-injecting a vaccine (Encepur ) into the ipsilateral quadriceps muscle. Her medical history was otherwise unremarkable. Symptoms of a viral infection such as fever, rash, and oral or genital lesions were not present, and recent exposure to tics was denied.
The patient was afebrile, her blood pressure was 170/110, and her heart rate was 92. The alignment of the spinal column was normal. On the right leg, there was a positive straight-leg raising test, weakness of knee extension, and a diminished patellar reflex. There was also slight hypaesthesia over the knee and the anterior aspect of the thigh. The Babinski sign was negative, and there was no evidence of meningism such as photophobia, neck-stiffness, or a positive Brudzinski sign.
The ESR was 7 mm/hr, her CRP was 8.9 mg/L, and the blood differential was normal. The remaining blood chemistry was negative, including tests for paraproteins, ANA, and HIV. Abdominal ultrasound excluded urine retention and other intraabdominal pathology. On contrast-enhanced MRI, there was no compression of the spinal roots or the cauda equina and no involvement of the cranial meninges. The patient refused a lumbar puncture.
We diagnosed a sensorimotor radiculitis of the fourth lumbar root secondary to TBE vaccination. A 5-day course of prednisolone (1 mg/kg) did not influence symptoms and was thus discontinued. Three months later, the patient still required analgesics (NSAIDS, tramadol, and pregabalin) and had developed a pronounced weakness and atrophy of the quadriceps muscle and a foot drop of the affected leg. The motor and sensory function had started to return to normal at 6 months, and by 12 months, the deficit had vanished. In contrast to this, the headaches and difficulties to concentrate persisted at the one-year mark.