Skeletal Radiology

, Volume 38, Issue 3, pp 207–223

Imaging of painful scoliosis

Authors

  • Alun Davies
    • Department of RadiologyRoyal National Orthopaedic Hospital Trust
    • Department of RadiologyRoyal National Orthopaedic Hospital Trust
Review Article

DOI: 10.1007/s00256-008-0517-5

Cite this article as:
Davies, A. & Saifuddin, A. Skeletal Radiol (2009) 38: 207. doi:10.1007/s00256-008-0517-5

Abstract

Scoliosis is defined as a lateral deviation of the spine from the normal plumb line. Commonly, there is a rotational component and deviation also in the sagittal plane (kyphosis or hyperlordosis). When scoliosis presents in adults, it is often painful. In contrast, back pain in a child is considered rare, and serious underlying pathology should be excluded, particularly since idiopathic scoliosis is typically painless. A painful scoliosis in a child or adolescent, especially if the patient has a left-sided curve, should be examined thoroughly. The aim of this review is to illustrate the causes of a painful scoliosis in children, adolescents and adults.

Keywords

Painful scoliosisIdiopathic scoliosisVertebral tumoursAdult scoliosisOsteoid osteomaOsteoblastomaSpondylosisSpondylolisthesisIntra-spinal tumours

Introduction

Scoliosis is defined as a lateral deviation of the spine from the normal plumb line. Commonly, there is a rotational component and deviation also in the sagittal plane (kyphosis or hyperlordosis).

When scoliosis presents in adults, it is often painful. In contrast, back pain in a child is considered rare, and serious underlying pathology should be excluded, particularly since idiopathic scoliosis is typically painless. A painful scoliosis in a child or adolescent, especially if the patient has a left-sided curve, should be examined thoroughly.

A review of the literature suggests that the association of pain and underlying pathology in idiopathic scoliosis has not been well documented. The most comprehensive study into this was carried out by Ramirez et al. [1]. In their retrospective review of 2,442 patients with idiopathic scoliosis, 560 patients had back pain at the time of diagnosis, and of these, only 9% were shown to have an underlying pathological condition [1]. Causes included spondylolysis or spondylolisthesis, Scheuermann kyphosis, syrinx/hydromyelia, herniated disc, tethered cord and intra-spinal tumour in decreasing order of incidence. Smaller case series have demonstrated much higher incidences of underlying pathology, with osteoid osteomas (OOs) and osteoblastomas (OBs) being frequent findings [2, 3]. The likely reason for this wide variation in reported incidence of underlying pathology is the differences in defining incidence of pain in these patients.

The aim of this review is to illustrate the causes of a painful scoliosis in children, adolescents and adults.

Imaging modalities

Plain radiography is recommended as the initial investigation in patients with scoliosis. This allows the diagnosis and also the evaluation of the degree of curvature by measuring the Cobb angle. Underlying osteogenic anomalies can also be identified, which can help direct further imaging.

Multi-detector computed tomography (CT) with 2D multi-planar reformatting and 3D reconstruction are important in the pre-operative evaluation of vertebral abnormalities due to anomalous formation or segmentation of the vertebral column. In addition, CT is valuable in the assessment of vertebral tumours as it is superior to magnetic resonance imaging (MRI) at evaluating cortical bone destruction and the calcified tumour matrix. In addition, it gives greater detail of subtle abnormalities of the neural arch.

MRI is the imaging modality of choice for assessment of the contents of the spinal canal, allowing direct, non-invasive imaging of the entire vertebral column, including the cord and other spinal canal contents. It has been shown to be more sensitive and specific in the assessment of intra-spinal anomalies when compared to myelography [4, 5]. The whole of the spine must be imaged using a combination of T1- and T2-weighted sequences (without and with fat suppression), with the aim of identifying any correctable causes for the scoliosis. In addition, T1-weighted images after the administration of gadolinium should be considered, especially if there is a cord tumour.

The role of 99m-technetium methylene diphosphonate (MDP) bone scintigraphy is now diminishing, but it may still be of value in the assessment of OO.

Classification

Scoliosis can be divided into two major types: non-structural and structural. Non-structural scoliosis is mild, non-progressive and fully correctable by ipsilateral bending. It may be postural or compensatory, and spinal motion is symmetric bilaterally with no evidence of rotational deformity. In structural scoliosis, there are vertebral morphological changes, which include wedging and rotation. Based on its aetiology, structural scoliosis may be idiopathic (80%), congenital (osteogenic; 10%) or associated with a variety of developmental, neuromuscular and neoplastic causes, which are an important subset to identify. Idiopathic scoliosis is further subdivided according to the age at which the disorder presents: infantile (birth to 3 years), juvenile (4–9 years) and adolescent (10 years and beyond). More recently, this classification has been modified to early and late onset, with the division being between 5 and 7 years. Table 1 shows a classification of scoliosis.
Table 1

Classification of scoliosis

Aetiological classification of scoliosis

Idiopathic

  Infantile (0–3 years)

  Juvenile (3–10 years)

  Adolescent (>10 years)

Congenital

Osteogenic

  Anomalous formation

    Wedge vertebrae

    Hemivertebra

  Anomalous segmentation

    Fused vertebra

    Unilateral bar

    Fused ribs

Neuropathic (spinal dysraphism)

  Tethered cord

  Syringomyelia

  Chiari malformations

  Diastematomyelia

  Meningocele/myelomeningocele

Neuromuscular

  Neuropathic

    Upper motor neurone

      Cerebral palsy

      Spinocerebellar degeneration

    Lower motor neurone

      Poliomyelitis

  Myopathic

    Duchene muscular dystrophy

    Arthrogryposis

Developmental syndromes

  Skeletal dysplasias (e.g. osteogenesis imperfecta)

  Skeletal dystosis (e.g. neurofibromatosis)

Tumour associated

  Vertebral

    Osteoid osteoma

    Osteoblastoma

    Aneurysmal bone cyst

    Langerhans cell histiocytosis

 Intra-spinal

  Extra-medullary (e.g. neurofibroma)

  Intra-medullary (e.g. astrocytoma)

There are numerous potential causes for a painful scoliosis (Table 2). The pain can be considered primary due to the underlying pathological cause for the deformity, e.g. a painful vertebral tumour such as an OO. Alternatively, the pain can be consequent to the mechanical spinal deformity resulting in, for example, facet joint degeneration.
Table 2

Causes of painful scoliosis

Potential causes of a painful scoliosis

Vertebral tumours

  Osteoid osteoma

  Osteoblastoma

  Aneurysmal bone cyst

  Langerhans cell histiocytosis

Intraspinal tumours

 Extra-medullary (e.g. neurofibroma)

 Intra-medullary (e.g. astrocytoma)

Infection

  Tuberculosis

  Discitis

  Osteomyelitis

Scheuermann kyphosis

Disc disease

  Disc herniation

  Schmorl’s nodes

Spondylolysis

Spondylolisthesis

Degenerative

 Facet joint arthritis

 Spinal stenosis

 Nerve root compression

Vertebral tumours

Vertebral or intra-spinal tumours can predispose to spinal deformity. OO and OB are the commonest primary vertebral tumours associated with scoliosis [2]. For a scoliosis to develop, the muscle spasm must be unilateral and, therefore, associated with a lesion to the side of the midline. It has been shown that an asymmetric location of the lesion within the neural arch or vertebral body is the most significant factor that leads to the development of scoliosis [6]. It would be expected that the curve apex would be at the level of the lesion. However, this is not always the case. Lesions in the lower lumbar vertebrae may be associated with pelvic tilt and curves with the apex above the lesion (Fig. 1a,b). [7], whereas cervical lesions commonly result in cervicothoracic or thoracolumbar scoliosis. It is thought that paravertebral muscle abnormalities extending over multiple levels would be able to produce primary cervicothoracic curves or primary thoracic curves with compensatory lumbar curves.
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Fig. 1

OO of the L5 vertebra. a Anteroposterior (AP) radiograph showing a very mild, right thoracic scoliosis and a sclerotic right L5 pedicle (arrow). b Sagittal reconstructed CT scan through the right side of the L5 vertebra showing a low attenuation nidus (arrow) with surrounding sclerosis located in the inferior aspect of the pedicle

Osteoid osteoma

OO was first described in 1935 as a distinct pathological entity [8]. The majority of cases occur in patients under 25 years of age, with 20% occurring in the spine. The commonest location is in the lumbar region (59%) with the nidus found in the neural arch in the majority of patients [911].

The classical presentation is that of a painful scoliosis, the spinal deformity being secondary to reactive muscle spasm. Although the pain is characteristically relieved by aspirin [9, 12], less than two thirds of patients have these typical symptoms [13]. In most cases of spinal OO, radiographs demonstrate an area of neural arch sclerosis at the apex of the concavity (Fig. 2). Due to the complex overlapping anatomy of the spine, the detection and localisation of a nidus on plain radiographs is difficult compared with lesions in the long bones (Fig. 3). This is especially true in the thoracic region where the nidus is often not evident [1416]. Radiographs are normal in a small number of cases of spinal OO [13, 17].
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Fig. 2

OO of the T12 vertebra. AP radiograph showing a left thoracolumbar scoliosis with a sclerotic pedicle at the curve apex (arrow)

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Fig. 3

OO of the L2 vertebra. a AP radiograph showing a left lumbar scoliosis with the apex at L2/3 and no visible bone abnormality. b Coronal reconstructed CT scan through the neural arch demonstrates a lucent nidus (arrow) with surrounding sclerosis in the right L2 inferior articular process

Bone scintigraphy has been advocated to localise the vertebral level in young patients with clinically suspected OO, with subsequent targeted CT. Bone scintigraphy is almost invariably positive, with avid uptake on a triple-phase study due to the vascular and osteoblastic nature of the nidus [13, 14]. The typical scintigraphic features of OO consist of a rounded area of intense activity (Fig. 4), corresponding to the tumour nidus, with a surrounding area of slightly less increased activity due to the reactive bone changes. These features have been referred to as the ‘double-density’ sign [18], but this finding is infrequently seen in vertebral lesions [19]. One possible reason for this difference is the presence of less adjacent reactive bone formation in the cancellous bone compared to the cortical bone.
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Fig. 4

OO of the T8 vertebra. PA view 99m-Tc MDP bone scan demonstrating a focal area of intense uptake corresponding to the nidus with associated scoliosis

The characteristic CT appearance of OO is the presence of a low attenuation nidus with central mineralisation and varying degrees of perinidal sclerosis (Fig. 5) [9]. In the presence of classical symptoms and abnormal radiographs, CT is the preferred examination for confirming the diagnosis and localising the lesion prior to treatment. However, in the absence of classical clinical features, MRI is usually the next investigation. The nidus of an OO can have a very heterogenous and variable appearance on MRI, making lesion characterisation difficult [2022]. Gadolinium administration has been suggested to improve conspicuity and detection of the nidus [2024]. On non-enhanced MRI, the nidus is optimally visualised on T2-weighted sequences as a hypo-intense lesion surrounded by marrow and soft tissue oedema (Fig. 6a,b) [25]. Oedema in the pedicle and lamina extending anteriorly to involve a third to two thirds of the posterolateral vertebral body should raise the suspicion of OO (Fig. 6b,c). Oedema can also be seen in the neural arch at an adjacent level to that which harbours the nidus (Fig. 6a) [25]. Denervation oedema and fatty atrophy of the paraspinal muscles on the side of the lesion is also a common finding (Fig. 6d), as with spinal OB [14]. Spinal OO can be successfully treated with minimally invasive CT-guided laser photocoagulation or radiofrequency ablation of the tumour nidus [26, 27].
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Fig. 5

OO of the L3 vertebra. Axial CT scans showing a the characteristic appearance of an OO with a low attenuation nidus and central mineralisation and b surrounding perinidal sclerosis involving the pedicle, transverse process and lamina

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Fig. 6

OO of the L1 vertebra. a Sagittal T2-weighted fast-spin-echo MRI showing the tumour as a low signal intensity mass (black arrow) extending into the left L1/2 exit foramen, with oedema in the vertebral body and posterior elements of the L1 vertebra (black arrowhead) and also in the adjacent L2 pedicle (white arrow). b Axial T2-weighted fast-spin-echo MRI through the L1 vertebra, showing the hypo-intense nidus (black arrow) within the left pedicle and reactive oedema extending into both the vertebral body (white arrowhead) and the lamina and transverse process (black arrowhead). c Sagittal T2-weighted fast-spin-echo MRI shows the extent of oedema within the vertebral body (arrow). d Axial T2-weighted fast-spin-echo MRI showing oedema within the adjacent left psoas muscle (long arrow) and left erector spinae muscles (arrowhead)

Osteoblastoma

OB is a rare tumour that accounts for less than 1% of all bone tumours [28]. However, more than 40% of cases are located in the spine [2], where it usually involves the neural arch [2931]. Involvement of the vertebral body is extremely rare but can present with similar symptoms and deformity [3234]. There may be some delay in diagnosis, especially in adolescents who have some degree of scoliosis with no obvious radiological abnormality. Back pain is always the presenting symptom, and more than 50% of patients present with an associated spinal deformity [30]. A structural scoliosis may occur in approximately 31% of patients due to the delay in diagnosis and treatment [3].

Differentiation from OO is based mainly on the size of the lesion and its behaviour. Various authors have suggested that lesions above 1 [35], 1.5 [36] or 2 cm [37] should be classified as OB. However, lesions that have destroyed the cortex and produced an extra-osseous mass should be classified as OB regardless of size, since this growth pattern is not a feature of OO [38].

OB is confined to the neural arch of the vertebra in approximately 66% of cases, but the extension from the pedicle into the posterolateral aspect of the vertebral body is not uncommon [39]. Lesions confined to the vertebral body are rare, occurring in approximately 3% of cases [39].

OB is usually lytic and expansile (Fig. 7a). Matrix mineralisation is identified in 55–72% of cases [35, 36] and may be so extensive that the lesion appears predominantly sclerotic. Cortical destruction may be seen in up to 62% of cases and may result in neural compression [35].
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Fig. 7

Spinal OB. a AP radiograph showing a left lumbar curve with a lytic lesion (arrow) expanding the right L3 pedicle. b Axial CT scan through T9 showing an expansile lesion (arrows) with a calcified tumour matrix arising from the deep aspect of the left lamina and extending into the posterior spinal canal

On scintigraphy, OB demonstrates non-specific but intense, well-defined focal increased activity [33]. A negative bone scan has never been reported in patients with spinal OO or OB.

CT performed without contrast material is better than MRI for the evaluation of cortical bone destruction and calcified tumour matrix (Fig. 7b), whereas MRI is better than CT for the delineation of spinal cord compression [40] and reactive bone and soft tissue changes. The MRI appearances of spinal OB are varied, with tumours returning low or high signal intensity on both T1- and T2-weighted sequences (Fig. 8a,b). Tumours enhance following gadolinium administration in keeping with the vascular nature of the lesion (Fig. 8c). MRI may demonstrate low signal on both T1- and T2-weighted sequences in the adjacent bone marrow due to reactive sclerosis, but low signal on T1-weighted sequences and high signal on T2-weighted sequences due to bone marrow oedema are also seen; oedema may involve adjacent vertebrae and soft tissues (Fig. 8b) [41].
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Fig. 8

Spinal OB. a Sagittal T1-weighted spin-echo MRI shows an intermediate signal intensity lesion (arrow) arising from the right L3 lamina and extending into the posterior spinal canal. b Axial T2-weighted fast-spin-echo MRI showing a hypo-intense mass (arrows) centred on the right lamina and expanding into the spinal canal resulting in mild thecal sac compression. Oedema is seen in the erector spinae muscles (arrowhead). c Post-contrast T1-weighted spin-echo MRI shows moderate, uniform enhancement of the lesion (arrow)

Aneurysmal bone cyst

Aneurysmal bone cyst (ABC) is a benign cystic bone lesion, which represents either a true primary tumour or may develop within a pre-existing lesion (e.g. giant cell tumour, chondroblastoma). Patients with ABC usually present before 20 years of age, and the spine is involved in approximately 11% of cases, most commonly at the lumbar level [42].

The posterior elements are always involved with not infrequent extension into the vertebral body or ribs [42, 43]. Unlike OO and OB, the scoliosis associated with ABC is typically structural due to unilateral vertebral collapse (Fig. 9a).
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Fig. 9

Vertebral ABC. a Coronal T2-weighted fast-spin-echo MRI of the thoracic spine showing asymmetric T4 vertebral body collapse resulting in a thoracic scoliosis. b Coned AP radiograph showing a lytic lesion (arrows) in the left side of the L3 vertebra, with marked cortical thinning. c Axial CT scan showing a large lytic lesion (arrows) with well-defined, scalloped margins (arrowheads) involving the right neural arch and body of L1. d Axial T2-weighted fast-spin-echo MRI showing an ABC of L3 demonstrating multiple fluid–fluid levels (arrows)

Spinal lesions frequently present with neurological symptoms. Pain is invariably present and is either localised to the back or is secondary to the involvement of a nerve root or the spinal cord [43]. Plain radiographs (Fig. 9b) and CT (Fig. 9c) demonstrate a lytic expansile lesion associated with cortical thinning or loss [42]. The lesion margins are usually well defined and commonly scalloped (Fig. 9c) but appear poorly defined in approximately 14% of cases. Fluid–fluid levels can be seen, optimally on sagittal or axial T2-weighted MRI (Fig. 9d), with MRI providing a better assessment of spinal canal extension and the degree of nerve root or cord compression [44]. Enhancing septae may also be seen on MRI following intra-venous gadolinium.

Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a tumour-like lesion originating from the over-production and accumulation of histiocytes. The estimated incidence is 1 per 200,000 [45]. In the spine, LCH most commonly involves the vertebral bodies, frequently in a multi-focal manner [46]. The involvement of the neural arch is very rare. LCH is most common in the first or second decades of life with a mean age of 6.4 years at presentation [47]. The most common complaint is pain, especially at night. When LCH involves the spine, it normally causes only localised neck or back pain, with neurological symptoms being rare and usually limited to mild parasthaesia or radiculopathy [48]. The thoracic vertebrae are most commonly involved, with the disc spaces preserved [47, 48]. Spinal involvement results in variable degrees of collapse with the most severe appearance being complete vertebra plana [46], and LCH is the most common cause of vertebra plana in children [47, 49]. However, it can rarely appear as a hemivertebra with resultant scoliosis [50]. MRI findings in LCH are non-specific and can simulate other bone lesions including osteomyelitis, OB and Ewing sarcoma [51, 52]

Malignant tumours and infection

Metastatic lesions or myelomatous deposits affecting the vertebrae frequently cause vertebral collapse due to bony destruction, resulting in kyphosis. However, if the tumour causes predominantly unilateral collapse, this will result in a structural scoliosis (Fig. 10). Similarly, primary malignant tumours of the spine such as Ewing sarcoma can occasionally result in a scoliosis (Fig. 11)
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Fig. 10

Spinal metastasis. a AP radiograph of the lumbar spine shows unilateral left-sided collapse of the L3 vertebral body, with an absent pedicle sign (arrow). b Axial T2-weighted fast-spin-echo MRI shows a low signal intensity soft tissue mass extending outside the vertebral body (arrows) and into the spinal canal and pedicle. c Coronal reformatted post-contrast CT scan showing the metastatic unilateral L3 vertebral collapse (arrow) and the large right apical primary lung carcinoma (arrowhead)

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Fig. 11

Thoracic vertebra Ewing sarcoma. a Coronal T2-weighted fast-spin-echo MRI shows a tumour arising from the left T9 pedicle compressing the thoracic spinal cord, with associated right thoracic scoliosis. b Axial T1-weighted spin-echo MRI showing a large mass (arrows) arising from the left pedicle with extension into the vertebral body, adjacent paravertebral soft tissues and spinal canal, causing spinal cord compression

Tuberculous (TB) spondylodiscitis is the most common site for osseous involvement by TB [53], with spinal involvement seen in up to 15% of cases. The clinical presentation is mainly of insidious pain (42%) [53]. With non-TB spondyodiscitis, the spine is involved by infectious organisms through hematogenous spread or from a contaminated contiguous source [54], the lumbar level being most frequently involved. An initial scoliosis may be non-structural due to pain, but if the infection remains untreated, vertebral destruction can result in kyphosis or less frequently scoliosis.

Intra-spinal tumours/syringohydromyelia

Scoliosis can be the initial presentation of an occult intra-spinal lesion. Intra-spinal tumours can be intra-medullary, most commonly ependymoma and astrocytoma (Fig. 12a), or extra-medullary, such as neurofibroma or meningioma. Alternatively, lipomas and dermoid cysts may be seen, typically in the setting of spinal dysraphism.
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Fig. 12

Intra-medullary astrocytoma. a Coronal T1-weighted spin-echo MRI showing an expanded cevicothoracic cord. Apart from a cystic area of low signal intensity (arrow), the tumour is iso-intense relative to normal cord. b Sagittal T2-weighted fast-spin-echo MRI showing the cystic areas within the tumour as areas of high signal intensity (arrows)

Spinal cord tumours can present as scoliosis without neurological signs, which can take years to develop [55, 56]. In a large series of 115 intra-spinal tumours, scoliosis was the presenting abnormality in 31 cases [57]. Inoue et al. found statistically significant differences in the presence of neuraxis malformations in scoliosis patients with moderate or severe pain compared to those whose scoliosis was pain-free [58].

Ependymomas and astrocytomas constitute up to 70% of intra-medullary neoplasms. Spinal cord ependymomas are the most common type in adults, whilst asrocytomas are more common in children [59].

Cord ependymomas occur most commonly in the cervical region with 44% involving the cervical cord and an additional 23% extending into the upper thoracic region [59]. Radiographs may demonstrate a scoliosis in up to 16% of cases, and canal widening with associated vertebral body scalloping, pedicle erosions or laminar thinning can also be demonstrated [60]. Most spinal cord ependymomas are iso- or hypo-intense relative to the cord on T1-weighted MRI images [6163], whilst on T2-weighted images, iso-intense tumours are as common as hyper-intense tumours [61]. Approximately 20–33% of ependymomas demonstrate the ‘cap sign,’ a rim of extreme hypo-intensity at the poles on T2-weighted images. This is thought to be secondary to haemorrhage [62, 64]. Cysts are also a common feature, with 78–84% of ependymomas having at least one cyst, most of these being of the non-tumoural (polar) variety [6163].

Astrocytomas (Fig. 12) most commonly involve the thoracic cord (67%) [61]. Scoliosis is seen in 24% of cases, with radiographs also demonstrating bony canal expansion, although this occurs less commonly than with ependymoma [65]. On MRI, astrocytomas are usually eccentrically located within the cord (57%), are ill defined and show heterogeneous enhancement [64, 65]. Cysts are a common feature, with both non-tumoural and tumoural types seen [65]. Even with these differences, it may not be possible to differentiate between the two entities on the basis of imaging features alone.

Syringomyelia occurs with congenital abnormalities, trauma or infection or may be associated with tumour or arachnoididitis. Hydromyelia refers to the dilatation of the central canal that is lined by the ependyma, whereas syringomyelia represents the dissection of cerebrospinal fluid (CSF) into the cord substance. The two conditions may not be distinguishable on MRI, or they may co-exist, and as such, the combined term syringohydromyelia is often used.

Seventy percent of patients with syringohydromyelia have an associated scoliosis [66], but little is known about the pain patterns in such patients. However, a study by Ozerdemoglu et al. found that 70 of 119 patients (59%) with syringomyelia associated scoliosis had pain at presentation. Backache, headache and neck pain were the most common types of pain. Leg pain was found predominantly in patients with a terminal syrinx. There was no apparent correlation between syrinx size and pain [67].

A syrinx occurring in childhood, which has significantly expanded the cord, may result in the expansion of the bony spinal canal that is evident radiographically. The syrinx itself appears as a region of CSF signal intensity within the cord, which is commonly expanded (Fig. 13a,b). T2-weighted sequences are especially useful in detecting a small syrinx, which may be missed on T1-weighted images.
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Fig. 13

Syrinx associated scoliosis. a AP radiograph showing a left thoracic curve. b Sagittal T2-weighted fast-spin-echo MRI showing a large syrinx within the cervicothoracic cord. Areas of reduced signal intensity (arrow) within the syrinx indicate high flow CSF

Disc disorders

In the absence of an underlying vertebral tumour/infection or intra-spinal abnormality, the aetiology of painful scoliosis is poorly understood. It is thought to include muscular pain due to eccentric loading about the curve apex, asymmetric facet joint loading resulting in facet joint degeneration or synovitis, discogenic pain or a combination of these [68].

Disc degeneration is seen to occur at the concave aspects of scoliotic discs [6972]; however, its progression to discogenic pain is poorly understood. A study looking at the relationship of degenerative disc findings on MRI in scoliosis patients found that overall disc degeneration was similar in patients with painful scoliosis and asymptomatic control subjects [73]. However, in the paediatric scoliosis patients, those with Schmorl’s nodes and inflammatory end-plate changes had more significant pain than those without, suggesting that symptoms in scoliosis patients may, in part, have a discogenic etiology. Disc herniation is a rare cause of pain in the scoliosis patient, with no evidence to suggest a higher incidence of disc herniation between patients with scoliosis and the general population [1].

Rarely, a reactive curve can occur secondary to pain and muscle spasm associated with an acutely prolapsed disc. In adolescents, disc herniation nearly always follows physical exertion and is therefore traumatic rather than degenerative. The size of the herniated disc tends to be larger in adolescents compared to adults as the annulus is healthy, and therefore, a small tear in the annulus induces the extrusion of a relatively large amount of nucleus pulposus (Fig. 14).
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Fig. 14

Discogenic scoliosis. a AP radiograph of the whole spine showing a mild left thoracolumbar scoliosis. b Sagittal T2-weighted fast-spin-echo MRI showing a degenerate L5/S1 disc with posterior nuclear prolapse (arrow)

Scheuermann kyphosis

Scheurmann’s diseases is a condition defined by vertebral wedging, end-plate irregularity and narrowing of the inter-vertebral disc space with or without disc prolapse and intra-vertebral disc herniation (Schmorl’s nodes) [74]. These changes classically result in thoracic spinal kyphosis. It is a condition of adolescents and young adults and is relatively common, found in 31% of boys and 21% of girls with back pain [76]. The etiology of Scheurmann’s disease is unknown. Scheuermann proposed that the kyphosis resulted from avascular necrosis of the ring apophysis of the vertebral body [74]. Schmorl suggested that the vertebral body wedging was caused by herniation of disc material into the vertebral body. Mechanical factors and repetitive trauma have also been considered to play a significant role [74]. It is likely that the etiology is multi-factorial. The criteria for the diagnosis of Scheuermann’s disease are: (1) greater than 5° of wedging of at least three adjacent vertebrae at the apex of the kyphosis, (2) end-plate irregularities and (3) a thoracic kyphosis of more than 45° [7577].

A mild scoliosis is not uncommon in patients with Scheurmann’s disease (Fig. 15) [78], with two types being described. Apical curves occur at the same level as the kyphosis due to vertebral body wedging in the coronal plane, while non-apical curves occur within regions of compensatory lordosis situated above or, more commonly, below the kyphosis. Scoliosis associated with Scheuermann’s disease seldom progresses to the extent that surgical correction is required, since the adjacent region of increased kyphosis maintains the axis of spinal rotation relatively anteriorly and thus protects against rotation. In addition and of greater importance, the mean age of onset of Scheuermann’s disease is late in the adolescent period, therefore limiting the potential for scoliosis to progress.
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Fig. 15

Scheuermann’s disease. a AP and b lateral radiographs of the whole spine showing a thoracic kyphosis with a mild right thoracic scoliosis. c Sagittal T2-weighted fast-spin-echo MRI showing the typical lower thoracic anterior vertebral wedging, end-plate irregularity, disc degeneration and Schmorl’s nodes (arrows)

Spondylolysis/spondylolisthesis

Spondylolysis is defined as a defect in the pars interarticularis, which is the weakest part of the vertebral neural arch. Spondylolisthesis is defined as the anterior displacement of one vertebra relative to the vertebra below, with the condition occurring when a component of the neural arch is compromised, together with degeneration of the associated inter-vertebral disc. Scoliosis arising in association with spondylolysis/spondylolisthesis falls into three categories. Firstly, the scoliosis may be idiopathic thoracic or thoracolumbar and represent a problem unrelated to the spondylolysis, although the lysis may be the cause of pain in these patients. Rick et al. found pars defects in 6.2% of cases of idiopathic scoliosis, which is only fractionally higher than the general population [79]. Secondly, a neural arch defect or facet hypoplasia may produce asymmetrical spondylolisthesis, resulting in a rotation of the slipped vertebral body and a compensatory thoracolumbar curve. In a study of 84 patients with symptomatic spondylolisthesis, the incidence of scoliosis was 42% with the majority being lumbar or thoracolumbar curves of less than 15°. The incidence was highest in patients with spondylolisthesis at the L4–L5 level and in those with dysplastic (type 1) spondylolisthesis (Fig. 16) [80]. These cases are important to diagnose since initial surgery must be aimed at the spondylolisthesis correction. Finally, the scoliosis may be due to muscle spasm.
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Fig. 16

Scoliosis associated with spondylolisthesis. a AP whole-spine radiograph showing a mild right lumbar scoliosis. b Lateral radiograph of the lumbar spine showing a grade 3 L5/S1 dysplastic spondylolisthesis with fragmentation of both L5 pars (arrow)

Adult scoliosis

Adult scoliosis is defined as spinal deformity in a skeletally mature patient with a cobb angle greater than 10° in the coronal plane. It can be divided into four major groups (Table 3). In adult scoliosis, the most frequent clinical problem is back pain, but patients also suffer with radiculopathy, neurogenic claudication and rarely with neurological deficit.
Table 3

Classification of adult degenerative scoliosis

Types

Type 1. Primary degenerative scoliosis, mostly on the basis of a disc and/or facet joint arthritis, affecting those structures asymmetrically with predominantly back pain symptoms

Type 2. Progressive idiopathic scoliosis in adult life of the thoracic and or lumbar spine, which progresses in adult life and is usually combined with secondary degeneration

Type 3. Secondary degenerative scoliosis

  a. Scoliosis following idiopathic or other forms of scoliosis or occurring consequent on pelvis obliquity secondary to leg length discrepancy, hip pathology or a lumbosacral spine

  b. Scoliosis secondary to metabolic bone disease (predominantly osteoporosis) combined with asymmetric arthritic disease and/or vertebral fractures.

Modified from Aebi [81].

Occasionally, it is difficult to identify the primary cause of the curve once it has progressed. Asymmetric disc degeneration leads to increased asymmetric load and therefore to a progression of the degeneration and deformity. The progression is further encouraged by osteoporosis, particularly in the post-menopausal female patient. Consequent destruction of facet joints, discs and ligaments ultimately leads to instability at one or more levels, resulting in lateral vertebral body subluxation (Fig. 17) and spinal stenosis. Associated back pain can be localised either in the concavity at the apex of the curve, or alternatively, facet joint pain can occur in the convexity either above or below the apex. Radicular pain may arise from foraminal stenosis at the curve apex on the concave side or from the convex side at the lumbosacral junction. In addition, the formation of osteophytes from the facet joints and the posterolateral vertebral end-plates, together with hypertrophy and calcification of the ligamentum flavum and joint capsules, may result in central canal and lateral recess stenosis.
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Fig. 17

Degenerative adult lumbar scoliosis. Coronal T2W fast-spin-echo MRI showing a right mid-lumbar scoliosis with advanced, multi-level degenerative disc disease and lateral slip of L2 on L3 (arrow)

In the context of evaluating the pain source in these patients, image-guided facet and nerve root blocks and discography can help in surgical planning, and if surgery is not feasible, then facet joint and nerve root injections may be used as a therapeutic tool [81].

Conclusions

Painful scoliosis has a variety of causes. The scoliosis can be secondary to an underlying pathological cause, e.g. vertebral tumour. The associated scoliosis in this instance can be non-structural due to muscle spasm induced by the painful lesion; if the diagnosis is delayed, then the scoliosis may assume a structural component with vertebral rotation. Unilateral vertebral destruction by tumour or infection can also result in a structural scoliosis. There should be a high index of suspicion in a child with a presumed idiopathic scoliosis presenting with significant back pain, and a careful search should be carried out for any radiological evidence of an underlying cause. It should be remembered that intra-spinal lesions can cause a painful scoliosis without any neurological signs. In other instances, back pain can be secondary to the scoliosis, e.g. discogenic or facet degeneration. This is especially true in adult scoliosis where back pain is the predominant symptom due to spinal degeneration. However, other causes of a painful scoliosis should not be missed in this group, such as scoliosis secondary to vertebral metastases or myeloma.

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© ISS 2008