Abstract
Objective Far-out syndrome (FOS) is a rare incident caused by L5 nerve root entrapment in the
far-out area, the L5–S1extraforaminal area between the transverse process and the
sacral ala. The purpose of this study is to disclose the middle-term surgical outcomes
of microscopic posterior decompression in the far-out area (MPDFA).
Material and Methods From June 2008 to November 2010, eight patients with FOS (six men and two women,
mean age 65.4 years) were treated with MPDFA. Their chief complaint was leg pain in
the L5 nerve root distribution area. Nerve root impingements in the far-out area were
confirmed by magnetic resonance imaging, computed tomography and selective radiculography.
Indications for MPDFA were given when pain was uncontrollable with conservative treatments
for more than 1 month. MPDFA was performed according to the following procedure: a
4-to-5–cm skin incision was made just above the far-out area. The far-out area was
exposed using Wiltse's intermuscular approach. The nerve root was decompressed with
partial resection of the transverse process and the sacral ala, and removal of the
iliolumbar ligament. Surgical outcomes were evaluated at periodical examinations with
the Japanese Orthopedic Score (JOA) and a Visual Analogue Scale (VAS) of the leg pain.
The mean follow-up period was 24.3 months (ranging from 12 to 40 months).
Results All patients had reduced radicular leg pain after their operations. The mean postoperative
hospital stay was 11.4 days, and the patients returned to their normal activities
of daily living immediately after discharge. Both JOA and the VAS scores improved
after surgery. The scores temporarily worsened in two patients with degenerative scoliosis;
the worsening was attributed not to recurrence of the radiculopathy but to pain arising
from knee arthropathy. The scores were maintained in the other patients at least until
the final examinations during the follow-up.
Conclusion MPDFA is a less-invasive surgery for treating FOS and can provide a good middle-term
surgical outcome.
Keywords
microscopic posterior decompression - far-out syndrome - L5 radiculopathy - intermuscular
approach - extraforaminal stenosis
