Spine
Symptomatic ossification of the anterior
longitudinal ligament with stenosis of the
cervical spine
A REPORT OF SEVEN CASES
J. Mizuno,
H. Nakagawa,
J. Song
From Aichi Medical
University, Aichi-gun
Aichi, Japan
J. Mizuno, MD, Associate
Professor
H. Nakagawa, MD,
Professor
J. Song, MD
Department of Neurological
Surgery
Aichi Medical University, 21
Karimata Yazako Nagakute,
Aichi-gun Aichi 480-1195,
Japan.
Correspondence should be
sent to Professor J. Mizuno;
e-mail: jmizuno@
amugw.aichi-med-u.ac.jp
©2005 British Editorial
Society of Bone and
Joint Surgery
doi:10.1302/0301-620X.87B10.
16742 $2.00
J Bone Joint Surg [Br]
2005;87-B:1375-9.
Received 16 May 2005;
Accepted 14 June 2005
Seven men with a mean age of 63.9 years (59 to 67) developed dysphagia because of
oesophageal compression with ossification of the anterior longitudinal ligament (OALL)
and radiculomyelopathy due to associated stenosis of the cervical spine. The diagnosis of
OALL was made by plain lateral radiography and classified into three types; segmental,
continuous and mixed. Five patients had associated OALL in the thoracic and lumbar spine
without ossification of the ligamentum flavum.
All underwent removal of the OALL and six had simultaneous decompression by
removal of ossification of the posterior longitudinal ligament or a bony spur. All had
improvement of their dysphagia. Because symptomatic OALL may be associated with
spinal stenosis, precise neurological examination is critical. A simultaneous microsurgical
operation for patients with OALL and spinal stenosis gives good results without serious
complications.
Although ossification of the posterior longitudinal ligament (OPLL) is associated with
radiculomyelopathy, ossification of the anterior longitudinal ligament (OALL) has not
been widely described since it is rarely symptomatic.1-5 Resnick et al6 and Resnick, Shaul
and Robins7 coined the term diffuse idiopathic
skeletal hyperostosis for Forestier’s disease and
ossification of the spinal ligaments has been
considered as a part of this entity.8,9 They
defined diffuse idiopathic skeletal hyperostosis
as showing calcification or ossification along
the anterior to anterolateral aspect of four contiguous vertebral bodies with relative preservation of the height of the intervertebral disc in
the affected areas,9 distinguishing it from
degenerative discogenic disease. In the past
dysphagia because of OALL has been confused
with that caused by degenerative disc disease
because of poor recognition of ossification
of the spinal ligaments.10-20 The management
of symptomatic OALL is still controversial.
Although conservative treatment with antiinflammatory medication may be effective,
aspiration pneumonia has been described1,17,21,22
and there may be myelopathy due to coexisting
spinal stenosis.3
We describe the clinical manifestations,
radiological diagnosis and surgical treatment
of symptomatic OALL in seven patients with
special emphasis on simultaneous surgery for
OALL and coexisting spinal stenosis.
VOL. 87-B, No. 10, OCTOBER 2005
Patients and Methods
Between January 1987 and December 2002,
seven patients with OALL who presented with
dysphagia were treated surgically. All were
men with a mean age of 63.9 years (59 to 67).
The dysphagia was due to oesophageal compression and all had radiculomyelopathy secondary to coexisting stenosis of the cervical
spine. Their clinical details are summarised in
Table I.
Clinicoradiological characteristics. In all cases,
the diagnosis of OALL was made on plain lateral radiographs. There was hyperostosis of
the anterior longitudinal ligament at several
levels with preservation of the disc height. The
degree of anterior projection and the shape of
the OALL were best visualised on transverse
CT scans. MRI was effective in evaluating
associated compression of the cord. OALL was
classified into three types on radiological studies. The segmental type was defined as partial
or total ossification over a vertebral body without involving the disc space. The continuous
type showed ossification over many disc spaces
as well as the vertebral body. In the mixed type
there was a combination of the segmental
and continuous types (Fig. 1). Of the seven
patients, two showed the segmental, three the
continuous and two the mixed types. In the
continuous and mixed cases OALL was associated with OPLL in the cervical spine and in the
segmental cases the spinal stenosis was caused
1375
1376
J. MIZUNO, H. NAKAGAWA, J. SONG
Table I. Details of the seven patients
Case
Age
(yrs)
Gender
Dysphagia Hoarseness
Neurological
symptoms
Type of
OALL*
c-OPLL†
OLF‡
th-OALL§ l-OALL¶
1
2
3
4
5
6
7
63
62
64
67
67
59
65
M
M
M
M
M
M
M
+++
++
+
++
+
+
+++
Myelopathy
Myelopathy
Myelopathy
Myelopathy
Myelopathy
Myelopathy
Radiculopathy
Mixed
Continuous
Mixed
Continuous
Continuous
Segmental
Segmental
+
+
+
+
+
-
-
+
+
+
+
+
-
+
+
++
-
+
+
+
+
+
-
* OALL, ossification of the anterior longitudinal ligament
† c-OPLL, cervical ossification of the posterior longitudinal ligament
‡ OLF, ossification of the ligamentum flavum
§ th-OALL, thoracic ossification of the anterior longitudinal ligament
¶ l-OALL, lumbar ossification of the posterior longitudinal ligament
patients and at two levels in four. Titanium interbody cages
were used for fixation after decompression.
Post-operative course. One patient was temporarily hoarse,
but otherwise no new symptoms occurred. This patient
wore a hard cervical collar for one month. All the patients
were able to swallow both liquid and solid food. All were
followed up for a mean of 17.1 months (12 to 36); None
developed recurrent symptoms or radiological evidence of
further ossification.
Illustrative cases
Case 1 (Table I). A 63-year-old man developed severe dys-
a
b
c
Fig. 1
Diagram of the radiological classification of ossification of the anterior
longitudinal ligament showing the a) segmental, b) continuous and c)
mixed types.
by cervical spondylosis. The patients with continuous and
mixed disease had coexisting OALL in the thoracic and
lumbar regions. Ossification of the ligamentum flavum was
not seen.
Operative procedures. A microscopic anterior approach was
used for removal of the OALL. A transverse skin incision
was employed in six patients in whom the OALL and spinal
stenosis were located at the same or at adjacent levels, while
a longitudinal incision was made in one patient in whom
the OALL and OPLL were at different levels. The platysma
was exposed and the operating microscope introduced.
Adhesions were present between the oesophagus and the
OALL which were separated using a microdissector. After
retracting the trachea and oesophagus the ossified mass was
incised and the anterior surface smoothed using ronguers
and a high-speed drill with a 5-mm burr. A decompressive
procedure for stenosis was carried out in six patients. The
other patient had a mild left hemiparesis because of previous cerebral infarction and decompression was not undertaken. Compression of the cord was seen at one level in two
phagia and mild hoarseness three months before admission.
He had a mild right hemiparesis after cerebral infarction
three years before. The dysphagia gradually deteriorated,
and he had difficulty in swallowing solid food. Neurological examination showed a mild hemiparesis, numbness
in both upper limbs, severe dysphagia and mild hoarseness.
Plain lateral radiography revealed OALL from C1 to C7
with prominent anterior projection of OALL from C2 to
C5. Stenosis of the spinal canal was present from C3 to C6
with a small segmental OPLL at C4 to C5. The anterior
longitudinal ligament of both the thoracic and lumbar spine
was ossified. The disc height in the cervical spine was relatively normal. MRI revealed marked compression of the
pre-vertebral soft tissue including the oesophagus and trachea. Resection of the OALL was undertaken from C2 to
C5 through an anterior approach using an operating microscope. Decompression of the spinal stenosis was not performed because this patient was hemiparetic on the right
side. There were adhesions between the OALL and the
oesophagus which required meticulous separation and gentle retraction of the oesophagus. The dysphagia and hoarseness immediately improved after operation (Fig. 2).
Case 7 (Table I). A 65-year-old man slowly developed dysphagia over a period of two years. There was also some
clumsiness in both hands for one year, but he was otherwise
healthy. Neurological examination showed clumsiness of
the hands and hyperaesthesia in C7/8 with severe dysphagia. A plain lateral radiograph revealed OALL from C4
to C6 and a posterior spur at C6/7. CT confirmed marked
anterior projection of the OALL compressing the pre-verteTHE JOURNAL OF BONE AND JOINT SURGERY
SYMPTOMATIC OSSIFICATION OF THE ANTERIOR LONGITUDINAL LIGAMENT WITH STENOSIS OF THE CERVICAL SPINE
Fig. 2a
Fig. 2b
1377
Fig. 2c
Figure 2a – A plain lateral radiograph showing the mixed type of ossification of the anterior longitudinal ligament (OALL) involving the
entire cervical spine. Figure 2b – CT showing marked OALL and slight
ossification of the posterior longitudinal ligament at C5. Figures 2c
and 2d – Tomography of the thoracic and lumbar spine showing
OALL. Figure 2e – Plain radiograph after operation showing the
smooth surface of the vertebral body after resection of the OALL.
Fig. 2d
Fig. 2e
bral soft tissue. MRI showed compression of the cord due
to cervical stenosis. A simultaneous anterior procedure
combined with removal of the OALL and decompression of
the spinal canal was performed. There were slight adhesions between the OALL and the oesophagus. He made a
good post-operative recovery (Fig. 3).
Discussion
The patients in our series were all men in the sixth or seventh decade as is seen in OPLL.8,9 Both the anterior and
posterior longitudinal ligaments run longitudinally along
the vertebral body from the cervical spine to the sacrum.
Because of the frequent association of OALL and OPLL,
the same mechanism may enhance ossification of these spinal ligaments,23,24 but none had ossification of the ligamentum flavum, which may be explained by the anatomical
difference between this structure and the anterior or posterior longitudinal ligament. Because the ligamentum flavum
VOL. 87-B, No. 10, OCTOBER 2005
is attached to the lamina segmentally it may be affected by
extension, flexion and rotational forces more than the longitudinal ligaments. Overstretching of the ligamentum flavum by neck movements may be required in addition to a
systemic hyperostotic factor for the initiation and progression of ossification, whereas dynamic stress would not be of
importance in OALL and OPLL.25,26
Neurological complications from OALL are rare. Myelopathy or radiculopathy in our patients was caused by
stenosis of the cervical spine due to coexisting OPLL or cervical spondylosis. The most common symptoms of OALL
are compression of the oesophagus and trachea.6,17,21
Although fewer than 10% of patients require surgical
decompression of these structures, aspiration pneumonia
and suffocation by aspiration of food have been
described.1,27 Dysphagia due to OALL which is severe or
resistant to conservative treatment should be treated by
decompression of the protruding ligamentous mass.
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J. MIZUNO, H. NAKAGAWA, J. SONG
Fig. 3a
Fig. 3b
Fig. 3c
Figure 3a – A lateral cervical radiograph with barium
contrast showing severe compression of the oesophagus because of segmental ossification of the anterior
longitudinal ligament (OALL) at C4/5. Figure 3b – T2weighted MRI showing compression of the pre-vertebral soft tissues, including the trachea and the oesophagus from C4 to C6 with mild compression of the cord
by a spur at C6/7. Figure 3c – CT showing anterior projection of the OALL. Figure 3d – Post-operative plain
radiograph showing resection of the OALL and fusion
of C6/7.
Fig. 3d
THE JOURNAL OF BONE AND JOINT SURGERY
SYMPTOMATIC OSSIFICATION OF THE ANTERIOR LONGITUDINAL LIGAMENT WITH STENOSIS OF THE CERVICAL SPINE
Radiological evaluation should include plain lateral
radiography and CT. MRI cannot differentiate OALL from
an anterior spur, although compression of the pre-vertebral
soft tissues or spinal cord is well demonstrated. A barium
meal and endoscopy may be undertaken for further evaluation of the oesophagus.1 The radiological patterns of the
segmental, continuous and mixed types in OALL are similar to those of OPLL.28 All continuous and mixed cases
were associated with thoracic and lumbar OALL, while
segmental OALL was isolated in our patients. This suggests
that radiological evaluation should be performed in the
thoracic and lumbar spine as well as in the cervical region
because compression of the trachea and oesophagus can
occur at the upper thoracic level. Stuart21 and UnderbergDavis and Levine17 described oesophageal compression by
the thoracic spine. Segmental OALL and an anterior spur
may be confused because of their clinical and radiological
similarity. However, a decrease in disc height, a posterior
spur or instability indicate degenerative disc disease.
Although mild dysphagia due to OALL may be treated
with anti-inflammatory medication,14,16,29 surgical decompression should be performed when the symptoms are
severe.1,17,21,22 The use of an operating microscope for
resection of the OALL helps avoid complications such as
oesophageal injury. None of our patients had significant
morbidity or recurrent symptoms. Some advise cervical
fusion after resection of OALL21,30 but it can be treated by
simple resection of the ossified mass without fixation.
Six of our seven patients had simultaneous resection of
the OALL and decompression for spinal stenosis. A routine
anterior procedure enabled us to remove both the OALL
and coexisting OPLL or cervical spondylosis using a single
incision. Laminectomy or laminoplasty by a posterior
approach for spinal stenosis coupled with anterior resection of OALL may be an alternative procedure in cases of
OALL and spinal stenosis at three levels. Spinal fusion is
required after decompression because instability may produce further symptomatic osteophytes causing dysphagia.
Hirano et al13 and Suzuki et al,30 have each described a
patient with recurrent dysphagia due to an anterior osteophyte.
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
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