Clinical Findings of L1/2 Foraminal Stenosis

Abstract

Introduction: The lower lumbar foraminal stenosis is well recognized for the cause of failed back surgery and has recently received attention. However, little attention has been paid to the upper lumbar foraminal stenosis. The purpose of this report is to clarify the clinical and radiological findings of L1 radiculopathy caused by L1/2 foraminal stenosis.

Methods: Among 9,138 patients treated at the clinic for lumbar degenerative diseases, 16 patients who complained about unilateral low back pain and showed L1/2 foraminal stenosis on magnetic resonance imaging (MRI) were investigated. All of the patients showed improvement of the pain via L1 nerve root block. There were 12 males and 4 females with a mean age of 61 years (range, 39-86 years). For these patients the clinical symptoms and signs, and neurological and radiological findings were examined in detail.

Results: All patients complained of back pain in the posterior iliac crest. Ten patients (63%) complained about groin pain and six patients (38%) about pain around lateral of the greater trochanter. Three patients were examined via colonoscopy due to groin pain. No patients showed the pain of the distal thigh and the leg. Two patients complained of numbness at the inguinal area. The slight weakness of the iliopsoas muscle was recognized in one patient. No patients showed tendon reflex changes. Kemp test was positive in nine patients (56%). Plain radiographs showed degenerative scoliosis in seven patients (44%). On MRI findings, the round herniated masses were noted at the foraminal portion with coronal view. This sign revealed in six out of nine patients with L1/2 lateral disc herniation. All patients were relieved of their pain via L1 selective nerve root blocks; however, in three patients, the pain recurred immediately and the surgical procedures were required.

Conclusions: The characteristics of L1 radiculopathy due to L1/2 foraminal stenosis are unilateral low back pain in the posterior iliac crest with groin pain or greater trochanteric pain. The increasing pain by Kemp maneuver is recognized in 56% of the patients. From this study, the patients complaining of severe posterior iliac crest pain should be considered as suffering from L1/2 foraminal stenosis.