Appendix: Diagnostic Criteria for OPLL and Diagnosis and Treatment Algorithm

Diagnosis and Treatment Algorithm

Diagnostic Criteria for Ossifi cation of the Posterior Longitudinal Ligament of the Cervical Spine (Proposed by the Committee for Development of Clinical Practice Guidelines for OPLL)

The defi nition of OPLL proposed by the Committee is ossifi cation of the posterior longitudinal ligament of the cervical spine that causes clinical signs and symptoms.

Thus, OPLL fulfi lls the following conditions: (1) OPLL is recognizable on a plain lateral radiograph. When the lower cervical spine is not well delineated in a plain lateral radiograph, tomograms or computed tomogra- phy (CT) scans can be obtained. However, a small, ossi- fi ed lesion that can be recognized only with CT is not considered OPLL. (2) There must be an association of one or more of these clinical syndromes: compression myelopathy, radiculopathy, decreased neck motion sec- ondary to OPLL with or without pain.

Diagnosis and Treatment Algorithm for Ossifi cation of the Posterior Longitudinal Ligament (Proposed by the Committee for Development of Clinical Practice Guide- lines for OPLL)

A. When a patient complains of numbness in the peripheral parts of the extremities, clumsiness of the hands, or gait dysfunction

1 . Does the patient have spastic paresis?

Neurological examinations address the correct diagno- sis. Signs of myelopathy and radiculopathy should be

carefully observed. Tendon refl exes of the upper extremities may be decreased or diminished owing to impaired secondary motor neurons.

2 . Is OPLL revealed on the plain lateral radiograph?

Two-view anteroposterior and lateral radiographs are mandatory (Fig. 1). If the X-ray projection is not correct, the posterior margin of the vertebral body delineates a dual shadow that mimics the segmental type of OPLL.

3 . Does OPLL narrow the spinal canal?

Measure the space available for the cord and calculate the occupancy rate (Fig. 2).

4 . What is the severity of the myelopathy?

Assess the severity of the myelopathy using the evalua- tion criteria for cervical myelopathy proposed by the Japanese Orthopaedic Association (JOA score). Check for other possible causes of cervical myelopathy—such as cervical spondylotic myelopathy, spinal cord tumor, spinal bone tumor, and cervical spinal involvement of rheumatoid arthritis—and then proceed to the treat- ment algorithm (Fig. 3).

B. When a patient has axial symptoms 1 . Does the patient have neurological signs?

Follow the same diagnostic process as in A and then proceed to the treatment algorithm (Fig. 4).

299

300 Committee for Development of Clinical Practice Guidelines for OPLL

Fig. 1. Classifi cation of ossifi cation of the posterior longitudinal ligament (OPLL) by the Investigation Committee on the Ossifi cation of Spinal Ligaments, Japanese Ministry of Health and Welfare

A B

Fig. 2. Space available for the spinal cord (SAC). A space of 6 mm is considered critical for myelopathy. Film-tube dis-

lesion/developmental anteroposterior diameter of the spinal

canal) ×100. Values ≥40 indicate a high likelihood of

Spastic paraplegia

yes no

Plain X-ray

OPLL*2

no yes

Differential diagnosis Image measurement

Spinal canal stenosis

Peripheral neuropathy Motor neuron disease etc.

Unclear diagnosis

neurologist

no yes

Disease severity

mild severe

Orthopedic surgeon

Certified spine surgeon

Fig. 3.

302 Committee for Development of Clinical Practice Guidelines for OPLL

Fig. 4.

Neurological symptoms

no yes

Plain X-ray

OPLL*2

no yes

Differential dignosis*6 Image measurement*3

Spinal canal stenosis*4

mild severe

Orthopedic surgeon

Go to Fig. 3

aberrant peripheral nerve bundles (APNB) 68 acromegaly 30, 34, 39, 116

adipocyte 82, 90

alkaline phosphatase (ALPase) 61, 95

anatomical structure of the posterior longitudinal ligament 41

androgen 39 animal model 71, 77

anterior decompression 193, 205, 237

anterior decompression procedures, thoracic OPLL 225, 227 , 250

anterior fl oating method 166, 182, 209, 210 anterior horn neurons 102, 106

anterior procedure 181

anteroposterior (AP) diameter 34, 129 association study with candidate genes 19 astrocytosis 105

axial pain 197, 205 axial pain, laminoplasty 190

bone mineral density 14

bone morphogenetic protein (BMP)-2 61 , 93, 95, 99 bone morphogenetic protein receptor (BMPR) 61 bone morphogenetic proteins 55, 59

boomerang shape of the spinal cord 67 brain stimulation 157

C5 nerve root palsy 211, 212 calcifi cation 98

calcifi cation of the ligamentum fl avum 139 calciotropic hormones 37

calcium metabolic abnormality 29, 33 calciuric response 39

canal narrowing ratio 94 candidate genes 21

cartilage-derived morphogenetic protein 55 cartilaginous cells 52

cerebrospinal fl uid, leakage 222, 226, 237, 256 cervical myelopathy 30, 115

cervical orthosis 165 cervical traction 179

choice, surgical procedure 181, 222, 225, 266 chondrocyte-like cell 78, 79, 86

chromosome 21, 23

circumscribed-type, cervical OPLL 127, 135 circumspinal decompression 235, 240

classifi cation of OPLL based on CT fi ndings 133 classifi cation of ossifi cation of the posterior longitudinal

ligament (OPLL) 127, 128

classifi cation of thoracic ossifi cation of the posterior longitudinal ligament (OPLL) 122

classifi cation, OLF 265 clinical features 116

clinical manifestation of cervical OPLL 115

clinical manifestations of thoracic OPLL and OLF 121, 122 collagen 8, 21, 50, 61, 95

complication, laminoplasty 190 complications 237, 245, 256

complications, anterior fl oating method 211 compound muscle action potentials (CMAP) 279–281 computed tomography 132

computed tomography, thoracic spine 145 computer-assisted imaging guidance system 278 connective tissue growth factor (CTGF) 78, 79 conservative treatment 165, 179

continuous-type, cervical OPLL 117, 127, 197 corticosteroids 165

cross-sectional shape of the spinal cord 67, 178 CT-myelography 135

CT-myelography, thoracic spine 146

defi nition of OPLL 299 dekyphosis stabilization 239

deterioration, cervical myelopathy 196 development of myelopathy 117 development of OLF 49 development of OPLL 29

development of the incipient small OPLLs 42 diabetes mellitus 13, 30, 34, 112, 220

diffuse idiopathic spinal hyperostosis 7, 11, 19, 24, 37 disc degeneration 43

dural membrane 42

dural ossifi cation (DO) 42, 46

dynamic factors, myelopathy 14, 129, 165, 178

ectopic ossifi cation 71, 73, 89 en bloc laminectomy 187, 266, 268 en bloc laminoplasty 219 endochondral ossifi cation 52, 60 enthesis 52, 55, 99

epidemiological studies 7 estrogen 39

estrogen receptors 175 etidronate disodium 169

evaluation, spinal decompression 294 evoked spinal cord potentials (ESCPs) 112 evolution, laminoplasty 187

expansive laminoplasty 182

303

304 Subject Index

expansive laminoplasty, thoracic spinal lesions 261 expansive open-door laminoplasty 193

expansive Z-plasty 187 extensive laminectomy 251 extent of progression 173 extirpation, ossifi ed ligament 252 extracellular matrix genes 25

fenestration (laminotomy) 266 frameless stereotactic procedure 271 French-door laminectomy 266

gene encoding nucleotide pyrophosphatase 71 genetic analyses 8

genetic background 29 genetic factors 19 genetic linkage study 20 genetic survey 13

genome–wide linkage study 23 glial cells 65

glucose intolerance 37, 77, 89 gray matter 65

growth hormone 39

halter traction 165 head compression test 165 hemilaminectomy 266, 268

high-signal intensity area, MRI 112, 205 hill-shaped OPLL 132

histopathology of the ligamentum fl avum 50 history of OLF 49

HLA association 20, 21 HLA haplotype 8

human leukocyte antigen (HLA) 13 hyperinsulinemic 86

hyperleptinemia 80

hypertrophy of the posterior longitudinal ligament (PLL) 42 , 68

hypoparathyroidism 29, 33, 116

Insulin-like growth factor (IGF) 79 Insulin-like growth factor (IGF)-1 85 , 88, 89 Insulin-like growth factor (IGF)-I receptor β 83 image-guided surgery 271

immunohistochemical study of the spinal ligaments 61, 83–85 , 102

incidence of OPLL 7, 29, 115

indications, anterior decompression through posterior approach 249

indications, anterior fl oating method 209 indications, cervicothoracic laminoplasty 241 indications, laminoplasty 190, 193, 201, 220 indications, surgical treatment 181 insulin 37, 79

insulin receptor β 83, 85

insulin receptor substrates (IRS) 37, 78, 83, 88–90 internal rigid fi xation 182

intraoperative spinal cord monitoring 157, 279 intraoperative ultrasonography (IOUS) 264, 279, 287 The Investigation Committee on Ossifi cation of the Posterior

Longitudinal Ligament 3 irreversible pathological changes 67

Japanese disease 29

Japanese Orthopaedic Association (JOA) score 299

kyphosis 189, 194, 197, 201, 261, 294 kyphotic deformity 198, 219, 278

laminectomy 187

laminectomy membrane 219 laminoplasty 166, 187

late neurological deterioration 222 lateral column 66

lateral rachotomy 166 leptin 82, 88

leptin receptors 82 level diagnosis 153 ligamentous hypertrophy 44

long-term ( >10 years) results 182, 204, 211 long-term results double-door laminoplasty 203 lordotic curvature 189

magnetic resonance imaging 133

magnetic resonance imaging, thoracic spine 146 matrix vesicle calcifi cation 98

mechanical compression of the spinal cord 104 mechanical stress 54

mechanism of spinal cord damage 67

metabolic and endocrinological disorders 29, 33, 112 metabolic background of OPLL 40

microsatellite Genotyping 20 microscopic fi ndings of OPLL 43 midsagittal splitting laminoplasty 188

mixed-type, cervical OPLL 44, 117, 127, 179, 197 morbidity, OPLL 3

motoneuron 104

motor evoked potentials 151, 281 mouse model 101

multichannel monitoring 285 muscle relaxant 166

mushroom-shaped OPLL 132 myelography 135

myelography, thoracic spine 145

myelopathic intermittent claudication 123 myelopathy 34, 116, 134, 178

myotonic muscular dystrophy 116

natural course 177

natural course of myelopathy 117 neck pain 117

nerve root palsy 167, 221

nerve roots, tethering 190

neurological symptoms of OPLL 122 neurotrophic factors 105

neurotrophin 103, 104

nonsteroidal antiinfl ammatory drugs (NSAID) 165, 166

occupying ratio 182, 299

occurrence and development of OPLL 29, 33 open-door procedure 188

operative technique, anterior fl oating method 210 ossifi cation of ligamentum fl avum (OLF) 49, 60, 121, 124,

138 , 166, 227, 294

ossifi cation of paraspinal ligaments 46

ossifi cation of the posterior longitudinal ligament (OPLL) of thoracic spine 121, 124

ossifi cation progression 13, 171 osteophytes 50

parametric linkage analysis 71 parathyroid hormone 38, 61 pathogenesis of OPLL 33 pathological process 182

pathology of ossifi cation of the ligamentum fl avum 52 pathology of spinal cord lesions 65

pedigree surveys 8

peripheral nerve stimulation 151 plain radiography of thoracic spine 145 poor surgical results 198

positional candidate gene analysis 22 positional cloning 19

posterior column 66

posterior decompression 182, 228, 294

posterior decompression procedures, thoracic OPLL 250

posterior longitudinal ligament 41 postoperative management 203, 245 post-operative motor paresis 205 postoperative neck/shoulder/arm pain 167 PPi metabolism 73

prevalence 11

procedure, laminoplasty 202 prognosis 13, 14, 177, 220 prognosis, myelopathy 233 prognostic factors 221

progression, OPLL 137, 167, 169, 172, 175, 177, 183, 212, 213 , 222, 247

proliferation of chondroblastic cells 44 proliferation of fi broblast-like cells 44 prostaglandin 61

prostaglandin E

166

racial differences 29 radiculopathy 67, 116

radiographical classifi cation, OPLL 111 radiography 127

rate of narrowing in the spinal canal 131 recombinant human BMP-2 94

removal, thoracic OPLL 274

removal, OLF 275 roidism 29

segmental motor paralysis 197 segmental-type, OPLL 41, 127, 179, 197 sex hormones 39

sigmoid curvatures 189, 197

signal change in the spinal cord 134, 178 single nucleotide polymorphisms (SNPs) 20 skull traction 165

space available for the spinal cord (SAC) 14, 112, 117, 129, 166 , 181, 299

spinal accessory motoneurons 102, 103, 105 spinal cord evoked potentials 151, 157 spinal cord stimulation 151, 157 spinal osteoblastoma 61

spondyloepiphyseal dysplasia 116 spondylotic spurs 43

square-type OPLL 132 surgical complications 166 surgical pathology 46

surgical technique, anterior decompression through the posterior approach 250

surgical technique, cervicothoracic laminoplasty 241 surgical technique, circumspinal decompression 235 surgical technique, laminoplasty 194

surgical treatment 166 symptom, cervical OPLL 111 symptom, OYL 111

thoracic kyphosis 228 thoracic myelopathy 122 thoracic OPLL 131

tiptoe walking (ttw) mouse 22, 71 tomography, thoracic spine 145

transcranial electrical stimulation 151, 284 transcranial magnetic stimulation 151 transcranial stimulation 281

transforming growth factor- β 55, 59, 61, 93 transsternal approach 231

transthoracic approach 231 triangular-shaped spinal cord 67 type VI collagen 24

vitamin A 29, 33 vitamin D 38

vitamin D-resistant hypophosphatemic rickets 30, 33, 39, 116

waller degeneration of the spinal cord 69 white matter 65

wide laminectomy 166

Z-laminoplasty 201

zucker fatty rat 77