J. Mizuno et al., Analysis of hypertrophy of the posterior longitudinal ligament of the cervical spine, on the basis of clinical and experimental studies, NEUROSURGER, 49(5), 2001, pp. 1091-1097
OBJECTIVE: The goal of this study was to elucidate the pathophysiological f
eatures and treatment of hypertrophy of the posterior longitudinal ligament
(HPLL) of the cervical spine. HPLL is defined as a pathological thickening
of the posterior longitudinal ligament (PLL), causing spinal cord compress
ion. Incomplete decompression via removal of only coexisting herniated inte
rvertebral discs or spondylotic spurs might be performed, resulting in unsa
tisfactory surgical outcomes, when the PLL becomes abnormally thickened and
contributes to myelopathy.
METHODS: Patients with HPLL who underwent cervical decompression surgery we
re selected. Medical records and radiographs were retrospectively reviewed,
to obtain data on the pre- and postoperative clinical conditions of the pa
tients. Autopsy cases with HPLL proven by low-energy x-ray examinations wer
e chosen for assessment of the pathological characteristics.
RESULTS: Seventeen men and three women with HPLL underwent treatment via an
anterior approach, with direct removal of HPLL. Nineteen patients develope
d myelopathy, whereas one patient developed radiculopathy. Radiologically,
all HPLL cases exhibited coexisting herniated intervertebral discs and 10 e
xhibited small segmental ossifications of the PLL. Magnetic resonance imagi
ng or computed tomographic myelography revealed extensive cord compression
across the vertebral endplate level. The average preoperative Benzel modifi
ed Japanese Orthopaedic Association score was 10.8, and the average postope
rative score was 13.2. Histological examinations revealed thickening of the
PLL with proliferation of chondrocytes, together with various degenerative
changes.
CONCLUSION: Patients with HPLL can benefit from an anterior approach with d
irect removal of the HPLL and associated herniated intervertebral discs or
ossification of the PLL. Cervical polytomography, computed tomography, and
magnetic resonance imaging are useful in establishing a diagnosis of HPLL.