Journal ofNeurology, Neurosurgery, and Psychiatry 1989;52:1424-1426

Short report

Idiopathic dystonia and cervical spondyloticmyelopathyJ A WATERSTON,* M SWASH,* E S WATKINStFrom the Departments ofNeurology,* and Neurosurgery,t The London Hospital, Whitechapel, London

SUMMARY Cervical myelopathy developed in two patients with idiopathic torsion dystonia. Therewere marked spondylotic changes in both patients, probably attributable to the incessant dystonicmovements ofthe neck. Previous cervical spine surgery may have exacerbated the myelopathy in oneof the patients. Cervical myelopathy complicating idiopathic dystonia must be distinguished fromother causes of neurological deterioration, since it may be improved by appropriate neurosurgicaltreatment.

The clinical spectrum of dystonia encompasses a widevariety of movement disorders ranging from writer'scramp to generalised dystonia.' Idiopathic dystonia ischaracterised by the absence of clinical involvement ofother parts of the nervous system, such as thecerebellum, pyramidal system, retina and cerebralcortex. When there are signs of dysfunction in any ofthese systems, symptomatic dystonia, which issecondary to some underlying condition, should besuspected. Exceptions to this clinical axiom occur. Forexample, the other clinical features may complicatecorrective neurosurgical procedures or result fromunrelated neurological disease.2 We report a furtherexception to this axiom; the development of cervicalspondylotic myelopathy (CSM) caused or exacerbatedby dystonia.

Case reports

Case 1 A 61 year old man with spasmodic torticollisinitially presented with involuntary head and neck movementconsisting ofirregular jerking with torticollis, retrocollis, andfacial grimacing. There was clinical evidence of cervicalspondylosis, with weakness of left triceps and fingerextensors, absence of the triceps jerk and C7 sensory lossbut cervical myelography showed no evidence of cordcompression. No primary cause for the dystonia was found,and treatment with tetrabenazine and haloperidol was unsuc-cessful. Because of increasing disability, he was admitted for

Correspondence to: Dr M Swash, Department of Neurology, TheLondon Hospital, Whitechapel, London El I BB, United Kingdom.

Received 17 November 1988 and in revised form 24 May 1989.Accepted 27 June 1989

a trial of high cervical dorsal column stimulation. Anextradural stimulator was placed at the Cl level withoutlaminectomy, but this failed to alleviate his symptoms.

His disability remained unchanged for several years butthree months before his last admission, aged 67 years, hecomplained of increasing pain in his left shoulder, weaknessin both arms and legs, and urinary hesitancy. During thisperiod he became unable to stand or walk. On examination,the torticollis was unchanged, with jerking of the head to theright and some involuntary movement in the right arm. Therewas wasting of the intrinsic muscles of both hands andtriceps; all the tendon reflexes in the left arm and the righttriceps jerk were absent. There was a spastic paraplegia withbilateral extensor plantar responses and a sensory level waspresent at T1.

Cervical spine radiographs showed marked degenerativechanges, particularly at the C5, C6 and C7 levels, andmyelography revealed a sub-total, extradural block to theflow of contrast at C7/Tl with a narrow canal at C5/6 andC6/7 (fig 1). A decompressive laminectomy was performed atthese levels, but he did not improve. His dystonia becamemore marked and, after a stormy post operative course, hedeveloped respiratory failure and died.Case 2 This 19 year old student developed dystonia at theage of 14 years. Following the administration of prochlor-perazine after a routine appendicectomy he experienced ashort episode of torticollis and nine months later, developedfixed laterocollis to the left. The dystonia gradually worsenedand he developed generalised torsion dystonia with fixedflexion deformities of the left arm and leg. Investigationfailed to reveal an underlying cause.During the next two years he continued to deteriorate

despite medical treatment and a posterior cervical rhizotomy,becoming bed-ridden and affected by attacks of severetremor. A right thalamotomy abolished the tremor and fixeddystonic posture of his left limbs but failed to influence thefixed laterocollis. After insertion of a dorsal column

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1425Idiopathic dystonia and cervical spondylotic myelopathy

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Fig I Case 1: cervical myelogram. (a) AP view-subtotal block atC7/TI level. (b) Lateral view-narrowing ofspinal canal at C5/6, C6/7levels with deformation ofcord.

stimulator at the cervico-medullary junction there wasmarked improvement in his neck posture and mobility, andhe was able to return to college and to play sport.One year later he was readmitted with increasing general-

ised dystonia. A new power source for the dorsal columnstimulator was implanted, but he continued to deteriorate. Aleft thalamotomy was then performed with someimprovement in the dystonia affecting his right hand. Heinitially maintained this improvement but then over severalweeks noticed increasing limb dystonia with frequent dys-tonic spasms. Several explorations of the stimulator site andits connections were undertaken for recurrent technicaldifficulties. On the day following one such procedure hedeveloped rapidly progressive weakness in both arms,paraesthesiae below the neck and then the abrupt onset ofanalmost complete flaccid quadriparesis with respiratorydifficulties and a sensory level in the mid-cervical region. Amyelogram showed severe cervical spondylosis with markedkyphosis and forward subluxation of C2 on C3, and C3 onC4, and narrowing of the cervical canal at C3 and C4, thelevel ofthe stimulating electrode. There was angulation ofthecord at the level of the C3/C4 subluxation (fig 2).

Immediate exploration of the stimulator site was perfor-

med but little improvement occurred. A posterior cervicalfusion was then performed from the occiput to C4, withsynchronous anterior fusion at the C3/C4 level. Over thecourse of several months there was gradual improvement,particularly in the left arm and leg.

Discussion

It is prudent to recognise CSM as a cause of functionaldeterioration in the dystonic patient. In case 1, cervicalspondylosis without myelopathy was present at thetime of diagnosis of the dystonia. The patientdeveloped a cervical cord syndrome due to extraduralcompression from osteophytes at the lower cervicallevels. In case 2, severe cervical spondylosis withsubluxation and kyphosis caused an acutemyelopathy, probably due to cord traction across thekyphotic zone. In this case, although the cervical spinedeformity was probably exacerbated by previouscervical laminectomy, it seems likely that the spon-dylotic changes were due to the dystonia.

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Fig 2 Case 2: cervical myelogram, lateral view-subluxation ofC2 on C3, C3 on C4 with angulation andnarrowing at C3/4 level.

Compression is thought to be the main factorcausing myelopathy in cervical spondylosis,3 butischaemia may contribute to the cord damage.4 Barnesand Saunders5 found little predictive value inmeasurements of canal diameter, the amount ofposterior osteophytosis, and the degree of vertebralsubluxation. Other factors, such as traction ofthe cordover posterior osteophytes or compromise of thetransverse area of the cervical canal area during somemovements may be important, and post-operativereduction in cervical mobility correlates well withclinical improvement.5 Considerable movement andstretching of the cord occurs during normal neckflexion and quite large localised forces are producedby osteophytic bars projecting into the cervical canalduring such manoeuvres.6 The cord may be renderedischaemic during such movements, when the cross-sectional area of the canal decreases in extension by upto 16%.7 The normal canal lengthens in flexion andshortens in extension, but if cord movement is restric-ted by root sleeve and dural fibrosis or osteophyticbars, then traction forces may develop. Adams andLogue8 considered that cord traction was a significantcause of myelopathy especially in patients withmarked kyphosis, when the cord was stretched over aprominent spondylotic bar.

Surgical treatment ofCSM associated with dystoniais hazardous because it is difficult to immobilise thecervical spine post-operatively.. Despite this, earlyrecognition and treatment is necessary if an optimal

Waterston, Swash, Watkinsresult is to be achieved. Collar immobilisation isimpractical in patients with dystonia or torticollis. In asmall series of cases with CSM complicating athetoid-dystonic cerebral palsy, Hirose and Kadoya found themost severe radiological changes at C3/4, and reportedgood results with anterior discectomy, osteo-phytectomy and interbody fusion.9 Laminectomy mayincrease cord mobility by destabilising the cervicalspine, so that the results from this approach may notbe as favourable,'0 as demonstrated by the outcome inour case 1, and the lack of improvement followinglaminectomy in case 2.

Patients with dystonia or torticollis are at risk ofdeveloping premature cervical spondylosis as a resultof the excessive and continuous movement occurringin thejoints ofthe cervical spine,9'2 and this complica-tion is a potentially treatable cause of functionaldeterioration.

References

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