British Journal of Radiology (2007) 80, 384-387
© 2007 British Institute of Radiology
doi: 10.1259/bjr/19099813
Adult with progressive foot deformity
D S Kumar, FRCR, MS, DNB
and
L A Concepcion, MD, PhD
Department of Radiology, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK
Correspondence: Dr Dalavaye S Kumar, Radiology, Royal Liverpool University Hospital, 47 California Close, Great Sankey, Warrington WA5 8WU, UK. E-mail: dalavaye{at}gmail.com
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Case history
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A 25-year-old female presented with unilateral progressive foot deformity. On clinical examination she had a small right foot with pes cavus and the spine was within normal limits. There is no family history of foot problems or injury. Plain radiograph of the foot showed no remarkable abnormalities. MRI of the spine was subsequently performed.
What abnormalities are shown? What is the diagnosis? What is the uncommon clinical feature noted in this condition?
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Diagnosis
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The normal location of the tip of the conus medullaris is usually at the junction of the first and second lumbar vertebra in adults. Figure 1
demonstrates a low lying conus medullaris with tethered cord. Axial images (not shown) confirmed the position at the level of the fourth lumbar vertebra.
Figure 2a shows division of the spinal cord into two hemicords enclosed in a single dural sac. Figure 2b also shows a horseshoe kidney with connecting isthmus in front of the third lumbar vertebra. Figure 3a demonstrates a bifid spinous process of the fourth lumbar vertebra. Figure 3b shows lack of fusion of the posterior elements of the first sacral vertebra.
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Figure 2. AxialT2 weighted images at the level of (a) second lumbar vertebra and (b) third lumbar vertebra.
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Figure 3. AxialT2 weighted images at the level of (a) fourth lumbar vertebra and (b) first sacral vertebra.
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The diagnosis is Type II split cord malformation (SCM) with spinal dysraphism. Unlike the current case who presented in adulthood, most cases of SCM manifest in childhood.
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Discussion
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Split cord malformation is an uncommon form of spinal dysraphism that results in the division of the spinal cord into two hemicords [1–4]. The location of the lesion can occur at any level along the spine, but is most frequently seen in the lower thoracic or upper lumbar spine [1, 2].
SCMs occur as a result of abnormal development of the notochord between the fifteenth and eighteenth day of intrauterine life. SCMs may be isolated or associated with other dysraphisms (myelomeningocele, meningocele, spinal lipoma, neuroenteric cyst or dermal sinus), anomalies of the vertebral bodies (hemivertebrae, butterfly vertebrae, block vertebrae, kyphosis, scoliosis, spina bifida) or visceral malformation (kidney, rectum and uterus) [5].
Based on the state of the dural tube and the nature of the median septum, Pang et al classified SCM into two types [6]:
Type 1
The radiological hallmark is the osseous or osteocartilagenous midline septum. This septum divides the spinal canal into two halves. Each half contains a hemicord surrounded by a separate dural sac. Vertebral anomalies are the rule [7]. Type 1 SCMs are usually symptomatic [5].
Type 2
In this type, the two hemicords are contained in a single dural sac. A thin, fibrous septum separates the two hemicords. Vertebral anomalies are milder than in Type 1 [7]. This group is rarely symptomatic [5].
Most patients present during childhood and only a few cases are documented in the adult population [2–4, 9]. The mean age at the time of diagnosis is 5 years [2]. Skin anomalies at the base of the spine (midline hairy tuft, angiomas, dimple, sinus tracts and lipomas) occur in more than 90% of cases and are frequently the presenting complaints in newborn and children [5]. In the paediatric age group, the other presenting features can include scoliosis, progressive foot deformities, calf and foot atrophy, and bowel, bladder and gait disorders. These are caused by the traction on the conus secondary to the tethered cord. The presenting symptoms in adulthood differ from those in childhood [2]. The common presentations are lumbar radiculopathy, myelopathy and acute disc herniation. Other presenting symptoms include sensory and motor deficits, skeletal and foot deformities, and bladder and bowel disturbances [3].
MRI, because of its multiplanar imaging and ability to image both bones and soft tissues, is the best modality to evaluate these cases in adults. MRI is not only helpful to diagnose SCM, but also detects associated anomalies of the spinal column and its contents [2, 8]. In our case the associated horseshoe kidney was also demonstrated on MRI. Ultrasound is also helpful to assess associated anomalies of the genitourinary tract.
The role of prophylactic surgery in SCM in asymptomatic adults is controversial. Progressive neurological deficits, progressive bladder and bowel disturbances and persistent pain are the main indicators for surgery in adults [2, 3, 8].
This case is unique in that the association of SCM with horseshoe kidney was diagnosed in an adult patient. To the best of our knowledge only one case of horseshoe kidney has been reported in a 12-month-old boy with SCM [9]. The other renal anomalies reported in association with SCMs include renal ectopia, ectopic dysplastic renal tissue and absent unilateral kidney. All these cases were diagnosed in the paediatric age group [10, 11].
The cause of the association of SCM with renal anomalies is not clearly understood. Two hypotheses were proposed to explain this association. One of the hypotheses describes this being due to an aberrant induction of renal tissue by central nervous tissue. Although development of the nephrons is induced by the ureteric bud, central nervous tissue is also capable of inducing nephron formation in culture tissue taken from an undifferentiated Wilms' tumour [10]. This is further supported by the fact that nerve growth factor receptors in developing nephrogenic tissue are required for formation of the kidney tubules [10, 12]. The second hypothesis is that the neural tube defects interfere with the migration of renal tissue [10].
Although uncommon in adults, SCM should be considered in adults presenting with neuro-orthopaedic anomalies of the leg and foot, and further evaluation with MRI should be considered.
Received for publication December 1, 2005.
Revision received December 8, 2005.
Accepted for publication January 3, 2006.
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References
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- Sinha S, Agarwal D, Mahapatra AK. Split cord malformations: an experience of 203 cases. Childs Nerv Syst 2006;22:3–7.[CrossRef][Medline]
- Kaminker R, Fabry J, Midha R, Finkelstein JA. Split cord malformation with diastematomyelia presenting as neurogenic claudication in an adult: a case report. Spine 2000;25:2269–71.[CrossRef][Medline]
- Akay KM, Izci Y, Baysefer A, Timurkaynak E. Split cord malformation in adults. Neurosurg Rev 2004;27:99–105.[CrossRef][Medline]
- Wenger M, Hauswirth CB, Brodhage RP. Undiagnosed adult diastematomyelia associated with neurological symptoms following spinal anaesthesia. Anaesthesia 2001;56:764–7.[CrossRef][Medline]
- Sonigo-Cohen P, Schmit P, Zerah M, Chat L, Simon I, Aubry MC, et al. Prenatal diagnosis of diastematomyelia. Childs Nerv Syst 2003;19:555–60.[CrossRef][Medline]
- Pang D. Split cord malformation: Part II: Clinical syndrome. Neurosurgery 1992;31:481–500.[Medline]
- Tortori-Donati P, Rossi A, Cama A. Spinal dysraphism: a review of neuroradiological features with embryological correlations and proposal for a new classification. Neuroradiology 2000;42:471–91.[CrossRef][Medline]
- Prasad VS, Sengar RL, Sahu BP, Immaneni D. Diastematomyelia in adults. Modern imaging and operative treatment. Clin Imaging 1995;19:270–4.[CrossRef][Medline]
- Uzum N, Dursun A, Baykaner K, Kurt G. Split-cord malformation and tethered cord associated with immature teratoma. Childs Nerv Syst 2005;21:77–80.[CrossRef][Medline]
- Sharma MC, Arora R, Sharma P, Mehta VS, Sarkar C. Diastematomyelia associated with ectopic dysplastic renal tissue – report of a rare case. Childs Nerv Syst 2001;17:689–92.[CrossRef][Medline]
- Parmar H, Patkar D, Shah J, Maheshwari M. Diastematomyelia with terminal lipomyelocystocele arising from one hemicord: case report. Clin Imaging 2003;27:41–3.[CrossRef][Medline]
- Sariola H, Saarma M, Sainio K, Arumae U, Palgi J, Vaahtokari A, et al. Dependence of kidney morphogenesis on the expression of nerve growth factor receptor. Science 1991;254:571–3.[Abstract/Free Full Text]
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Case history
Diagnosis
