Internal iliac aneurysm presenting with lower back pain, sciatica and foot drop
A 64-year-old lorry driver, with a past medical history of hypertension controlled with valsartan, was referred by his General Practitioner (GP) to fracture clinic with lower left-sided back and sciatic nerve pain with numbness to the outer aspect of the foot.\nHe had initially been seen by his GP 3 weeks earlier complaining of lower back pain, dysuria and urinary frequency. Urine dipstick showed blood and protein and his urinary symptoms had settled with a 7-day course of trimethoprim. He had continued worsening lower back pain, so a full myeloma screen was organized including lumbar spine radiographs. Follow-up urinalysis was unremarkable, calcium was 2.62 (range 2.1–2.6), alkaline phosphatase was 134 (range 43–114) and ESR was 100, lumbar radiographs and PSA were normal, and Bence Jones Electrophoresis was awaited.\nFollowing a further review by the GP, he was now complaining of increasing lumbar back pain with associated limp but no neurological deficit, and feeling systemically unwell, so he was referred to the orthopaedic team for an urgent review for suspected myeloma or bony metastasis.\nOrthopaedic review detected sensory loss in the S1 dermatome and foot drop on the left side. He was clinically well. Urgent magnetic resonance imaging (MRI) demonstrated a 9 cm left iliac aneurysm in contact with the left L5 nerve root and in close proximity to the S1 nerve root (Figure a and b). There was also left ureteric dilatation with hydronephrosis. The spinal cord was normal.\nComputed tomography (CT) angiography was requested, and the patient was started on antibiotics because of the concerns over a mycotic aneurysm after discussion with the vascular team. CT angiography showed the internal iliac aneurysm obstructing the left ureter and abutting local nerve roots, with atheromatous disease within the common femoral arteries with an ectatic aorta (Figure a and b).\nThe radiologists proceeded to perform endovascular embolization of the left internal iliac to aid any further procedures. It was during direct catheterization of this aneurysm that it was noted to be blind ending with cross filling of the posterior division of the left internal iliac artery via collaterals from the right internal iliac artery (Figure a and b).\nAs a result, the aneurysm was managed by passing a stent graft from the left common iliac artery; this was extended with a second graft down into the distal external iliac artery.\nThe patient was discharged 2 days later with a foot-drop splint and outpatient physiotherapy to manage his peroneal nerve injury causing foot drop.\nSix weeks later, CT imaging showed a reduction in sac size although the patient was still having intermittent nerve root pain and the foot drop was still present.