Arachnoiditis Following Caudal Epidural Injections for the Lumbo-Sacral Radicular Pain
A 58-year-old male patient was treated with a course of caudal epidural injections for worsened left-sided sciatic/claudication pain secondary to the lumbar disc prolapse at L3/L4 level (, ). Patient had no constitutional symptoms or red-flag signs.\nPre-injection, the clinical examination revealed a slight altered sensation in the left L4 dermatome with the normal motor examination. The right lower limb neurology was normal. Routine haematological investigations were normal and negative for infections. His medical history included transient ischaemic attacks, ischaemic heart disease, and hypertension.\nThe left L4 nerve root block offered 2 weeks of pain-relief, before the patient experienced a recurrence of the symptoms. The decision to treat with a course of the caudal epidural injections was made. His first caudal epidural injection was uneventful.\nFour days following the second caudal epidural injection, the patient presented to the emergency department with a new onset of contralateral (right-sided) sciatica, which had worsened over the last 3 days. The patient's back pain had worsened, and he noticed difficulties in passing urine. He was afebrile and denied any chills, rigors or neck stiffness.\nThe examination revealed decreased sensations over the left L4, L5, and S1 with Medical Research Council (MRC) grade 3 power. He had absent bilateral knee and ankle reflexes with normal plantar reflexes. Bilateral straight leg rising was positive for sciatic irritation/stretch at 40 degrees.\nThe repeat magnetic resonance imaging (MRI) suggested a resolved L3, L4 disc protrusion with no new findings. The patient subsequently was noted to have a raised temperature of more than 37.8 degree, shooting pain in bilateral legs with associated paraesthesia in both feet. His blood investigations revealed raised inflammatory markers (C-reactive protein [CRP], 277; white cell count [WCC], 12.81×109 with neutrophilia).\nThe patient was started on empirical IV flucloxacillin after three random blood cultures taken during the febrile episodes. These cultures were subsequently found negative for bacterial growth. Multiple attempts at lumbar puncture to obtain the sample of cerebrospinal fluid (CSF; for evaluation) were very difficult and unsuccessful. Subsequently the patient deteriorated with worsening signs and symptoms of sepsis, which warranted a change in empirical IV flucloxacillin to IV vancomycin as per the microbiologist advice. Any further attempt to obtain CSF sample was abandoned at this stage. Following day, the patient developed a full loss of power in his left L4, L5, and S1 nerve roots, leading to full-blown left foot drop.\nThe repeat MRI at this stage showed diffuse enhancement of the nerve roots within the lumbar and sacral thecal sac which continued upwards. Meningeal enhancement of conus and lower cord was also noted along with 'clumping' of the nerve roots, which suggested infective arachnoiditis (). The patient also had a nerve conduction study, which showed marked denervation changes in the left L5-S1 distribution, indicating radiculopathy.\nThe patient gradually improved after 2 weeks of intravenous antibiotics (vancomycin), and the inflammatory markers (CRP, WCC, and erythrocyte sedimentation rate) returned to the normal limits. He made a slow recovery, but the left-sided foot drop persisted. He was discharged after being administered IV antibiotics for four-week duration. At the 6-month follow-up, the patient had no clinical signs of infection and was generally well with the normal inflammatory markers in the blood test. His left foot drop still persists.