Mr. J.B. is a 40-year-old machinist who has generally been in good health with the exception of hyperlipidemia treated with atorvastatin 20 mg daily. He presented with a two-week history of right back pain of about two weeks duration. This had been preceded by right leg pain, and he was now also noticing discomfort in the left leg as well. He denied acute trauma or injury, though he spent a lot of time standing on cement floors at work. The pain persisted when the patient was recumbent.
Physical exam revealed normal straight-leg raising and normal strength and sensation in the lower limbs but with some diminution in the right ankle jerk (AJ) reflex. Lumbar spine films were unremarkable, as were CBC and ESR. Physiotherapy and an NSAID were prescribed and on J.B.’s return 10 days later he reported “50% improvement” in pain levels. It was noted, however, that he’d developed some decreased sensation in the right lateral foot and the AJ reflex remained diminished.
Several weeks later J.B. was reassessed and found to have diminished strength in both lower limbs with bilaterally reduced AJ reflexes and symmetrically very brisk knee jerk reflexes. He also stated that a hot bath seemed to aggravate his symptoms. An urgent orthopedic consultation was arranged and a lumbar myelogram was performed, which was found to be normal. EMG studies were abnormal and non-specific, though suggestive of “multiple lumbosacral radiculopathies.”
JB’s weakness progressed rapidly and it was decided to obtain an MRI. What did this investigation show?
MRI of the spine revealed a T10-11 arteriovenous malformation (AVM). This condition results from a congenitally abnormal connection between arteries and the veins. Lacking capillaries to act as a buffer between the high pressure arterial system and the low pressure venous system results in a tangled plexus of vessels called a nidus (Latin for nest). This plexus can be very delicate and often bleeds. Depending on the location, the A-V malformation may never cause any problems, and 88% remain asymptomatic, often being found only on autopsy. In the wrong place, however, the results of a bleed can be devastating, resulting in a stroke or spinal cord injury.
Unfortunately for J.B. the location was in a sensitive area. The patient was urgently transferred to neurosurgery and had a T10-11 laminectomy and clipping of vessels. Even with expeditious treatment the patient was left with permanent, though mild, neurological sequelae.
This case reiterates the principles expressed in Dr. Drew Bednar’s excellent article “Red Flags in Back Pain” (www.parkhurstexchange.com/columns/pain/aug09_back_pain) in the July/August, 2009 issue of Parkhurst Exchange. J.B. presented with what first appeared to be fairly typical sciatica and only close follow-up revealed the subsequent worrisome progression of neurological findings. Besides the neurological signs and symptoms, other red flags included a lack of injury or serious trauma and the lack of improvement in pain when lying down.
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