Seizure-Induced Lumbar Burst Fracture Associated with Conus Medullaris-Cauda Equina Compression

Home , Burst fracture, Spinal cord compression

Diagn Interv Radiol 2011; 17:199–204 NEURORADIOLOGY © Turkish Society of Radiology 2011 CASE REPORT

Seizure-induced lumbar burst fracture associated with conus medullaris-cauda equina compression

Ashish Sharma, Laura Avery, Robert Novelline

ABSTRACT seizure-induced burst fracture of the spine is a rare clinical en- A 36-year-old male developed a burst fracture of the L1 verte- tity with only five cases reported in the medical literature to date bra following a seizure. The patient experienced conus-cauda equina compression resulting in urinary retention and patchy A (Table) (1–5). Although rare, it is extremely crucial to recognize sensory loss. An MRI of the spine revealed short tau inversion this emergent fracture because it predisposes the patient to irreversible recovery (STIR) hyperintensity at L1 with 70% loss of vertebral body height, 8-mm posterior bony retropulsion into the spinal neurological injury (4). canal and T2-weighted hyperintensity in the cord, which is Following a seizure, the most common site of a compression vertebral consistent with cord edema. A thorough physical exam and fracture is the midthoracic spine, and the most common site of a burst imaging is critical for immediate diagnosis of spine injuries to prevent grave neurological complications. vertebral fracture is the thoracolumbar junction of the spine (1, 4, 6). A burst fracture is more likely to cause neurological complications due to Key words: • seizure • burst fracture • vertebra • conus medullaris • cauda equina the fragmentation and comminution of the vertebral body, but a compression fracture remains asymptomatic in the majority of cases (7–9). For appropriate patient management, it is imperative to differentiate these two vertebral fracture types. Other forms of musculoskeletal trauma resulting from generalized seizure include fracture of the humeral head and neck, femur neck, pelvic bones, acetabulum and scapula, as well as dislocation at the glenohumeral joint, manubriosternal joint and femoroacetabular joint (1). Most of the cases of seizure-induced musculoskeletal trauma occur in patients with an isolated, unprovoked seizure. Such seizure episodes often occur due to electrolyte imbalance, drug overdose and/or drug withdrawal (1). Seizure-induced burst fracture of a vertebra is a non- traumatic fracture and may occur even at rest (1, 4). One such case of a nocturnal double thoracic burst fracture has been reported in the literature by Rupprecht et al. (3). In our report, we present the case of a 36-year-old male who suffered a seizure-induced burst fracture of the L1 vertebra with associated cord compression and right posterior shoulder dislocation with comminuted humeral head fracture. Diagnostic imaging and case management are also discussed.

Case report A 36-year-old left-handed male checked into the emergency department with an acute episode of a generalized tonic clonic witnessed seizure during sleep. There was no traumatic fall from a bed during the seizure. The patient appeared confused and developed a headache, but he denied a tongue bite, loss of bladder or bowel function, neck pain and weakness or numbness of the extremities in the immediate post-ictal period. The rest of the systems review was not pertinent. The From the Department of Radiology (A.S.  ashishdoc84@yahoo. co.in), Massachusetts General Hospital, Harvard Medical School, patient complained of soreness in his right shoulder and lower back in Boston, USA. the latter part the of post-ictal period. This patient had a past medical

Received 11 June 2010; revision requested 18 July 2010; revision received history of scoliosis and denied use of tobacco, alcohol or other rec- 28 July 2010; accepted 31 July 2010. reational drugs. His medication history included the use of dilantin for six years for epilepsy. The patient was otherwise very active and Published online 17 August 2010 DOI 10.4261/1305-3825.DIR.3638-10.2 functional, both at work and at home. There was no family history

199 Table. Tabulation of the cited literature for seizure-induced burst fractures

Author; Cause of seizure; year Number symptoms of (reference of musculoskeletal Musculoskeletal Neurological Pertinent Management and Study number) patients trauma trauma complication imaging findings follow-up

1 McCullen et al.; 1 Tricyclic T7 thoracic None X-ray of the shoulder: Anterior decompression 1994 anti-depressant vertebra burst Comminuted 4 part of T7, posterior fusion (1) overdose (amoxapine); fx, bilateral L. humeral head fx, using Cotrel-Dubosset post-ictal bilateral humerus head fx nondisplaced R. humeral instrumentation. shoulder soreness and surgical neck fx. Early mobilization at 5 days pain with movement with Jewett brace for 8 X-ray of the thoracic spine: as well as late (day weeks. Long-term follow- T7 compression fx with 7) midthoracic back up was not available. 50% height loss, T6 and discomfort. T8 wedging. CT and MRI of the thoracic spine: Type B T7 burst fx with 15% canal compromise with retropulsed fx segment. Bone scan: Increased uptake from T3–T8.

2 Youssef et al.; 1 Electrolyte imbalance; L1 and L2 None X ray of the lumbar spine: Initially treated with Risser 1995 lower back pain on vertebra burst fx Contiguous L1 & L2 cast but was unsuccessful. (2) day 5 burst fx with >50% loss Later underwent posterior of vertebral body height. spinal fusion with Cotrel- Dubosset segmental instrumentation and iliac crest bone grafting. Spine was stable at 1 year.

3 Rupprecht et al.; 1 Cerebral astrocytoma Double thoracic None NA NA 2001 with an epileptogenic vertebra burst (3) focus; back pain in fx, unstable fx immediate post-ictal of humerus and period and shoulder scapula pain on day 7.

4 Roohi et al.; 1 Infection with flu like L1 vertebra Conus CT and MRI lumbar Emergent spinal 2006 symptoms with no burst fx medullaris- spine: Burst fx of L1 decompression and (4) definite cause; cauda equina vertebral body with stabilization. Patient was denied lower back syndrome violation of spinal canal. placed in an orthotic pain on day 2 but Compression of the brace and referred to presented with conus medullaris and rehabilitative services. At weakness, loss of superior region of cauda 6 months post–surgery, reflexes, loss of equina was seen on MRI. patient had full recovery superficial pain and except for intermittent touch sensation in nocturnal incontinence, both lower extremities which was cured and saddle region completely by 5 years. along with diminished rectal tone.

5 Mehlhorn et al.; 1 Epilepsy; mild lower L2 and L4 None X-ray and CT of lumbar Fx stabilized with a 2007 back pain in the vertebra burst fx spine: Unstable burst fx dorsally instrumented (5) immediate of L2 and L4 vertebra internal fixator from post-ictal period. without major spinal L1 to L5 followed by canal violation hemilaminectomy and ventral spondylolisthesis. Long-term follow-up was not available.

fx, fracture; R, right; L, left

of seizures or recurrent fractures and the heart exam was unremarkable and ing upon inspection and tenderness dislocations. the abdomen was soft, non-tender and upon palpation. Restriction of motion On admission, the patient appeared non-distended. was present on both active and passive to be in no acute distress and had sta- The musculoskeletal exam of his movements. The lower back examina- ble vital signs. His lungs were clear with right shoulder was consistent with dis- tion revealed mild scoliosis, restricted no evidence of aspiration pneumonia, location/fracture and revealed swell- range of motion and tenderness upon

200 • September 2011 • Diagnostic and Interventional Radiology Sharma et al. a b

Figure 1. a, b. MRI T2W fast relaxation fast spin-echo sequence (FRFSE) axial (a) and T2W FRFSE sagittal (b) views of the thoracolumbar spine were imaged with parameters of TR/TE, 3800–4550/98–123.6 ms; FOV, 34–36 x 25.5–36 cm; matrix size, 256–512 x 160–256; section thickness, 3 mm; intersection gap, 0.5–1 mm; and echo-train length, 1–4. MRI showed an L1 burst fracture with a 70% loss of vertebral height (arrow, b) and retropulsion of the posterior vertebral elements of up to 8 mm into the spinal canal (arrows, a). Mild compression of the conus medullaris-cauda equina is present. T2W hyperintensity within the cord at the L1 level is consistent with cord edema. Mild loss of anterior vertebral height of L2 represents a chronic compression fracture.

palpation of the spinous processes at deficits showed a burst fracture of 50% loss of vertebral body height, and the L1 and L2 vertebra, consistent with L1 with STIR hyperintensity consist- a superior end plate compression de- a possible fracture. ent with an acute/sub-acute fracture. formity of L2, with an approximately The initial neurological exam was An approximately 70% loss of verte- 25–40% loss of vertebral body height within normal limits until day four bral body height was seen with pos- (Fig. 2). A CT of the lumbar spine con- post-admission. The patient gradually terior retropulsion of vertebral ele- firmed the lumbar X-ray findings and developed neurological deficits with ments into the spinal canal, resulting helped to diagnose a “burst fracture” of high residual urine retention (>1000 in asymmetric severe canal stenosis the L1 vertebral body. There was loss of mL) as well as tingling and paresthesia (right more than left). Posterior dis- height and retropulsion of bony frag- in the lower extremities and the sad- placement and mild compression of ments of up to 9 mm into the spinal dle region. Upon re-examination, the the conus medullaris-cauda equina canal that caused significant narrow- sensory loss exhibited a patchy distri- was present. T2-weighted (T2W) hy- ing. The CT also showed an anterior bution with loss of superficial pain and perintensity within the cord at the L1 compression fracture of the L2 verte- touch in the lower extremities. Prop- level was consistent with cord edema. bral body and a displaced L1 transverse rioception, superficial and deep ten- Severe foraminal narrowing at the L1/ process fracture (Fig. 3). don reflexes, motor strength, perianal L2 level was present. An L1 transverse The right shoulder X-ray demon- sensation and rectal tone were intact, process displaced fracture was demon- strated a posterior dislocation of the with a downgoing plantar response. strated. The L2 vertebra anterior com- humerus with a comminuted impact- The routine basic metabolic profile, pression fracture without STIR hyper- ed fracture of the surgical neck and a complete blood counts and urine toxi- intensity suggested a more chronic reverse Hill-Sachs impacted fracture of cology screen all tested normal. The compression fracture at this level. The the humeral head against the glenoid lumbar puncture showed a slight el- lower thoracic cord was normal. Addi- process. evation of protein. In the interim, the tionally, an MRI also showed an acute The patient was initially managed patient underwent an open reduction compression fracture of the inferior with a Keppra and thoracolumbar and internal fixation (ORIF) for the end plate of the T12 vertebra result- sacral orthosis (TLSO) brace for the right humeral head fracture along with ing in mild height loss, which was not lumbar fracture until neurological a reduction of the posterior dislocation evident on CT or X-ray (Fig. 1). deficits developed. On day 4, the MRI of the humerus. The initial X-ray of the lumbar spine of the lumbar spine warranted an im- An emergent MRI performed af- revealed an L1 vertebral body com- mediate surgical intervention. Intra- ter the appearance of neurological pression fracture, with a more than venous steroids were initiated, and a

Volume 17 • Issue 3 Seizure-induced lumbar burst fracture associated with conus medullaris-cauda equina compression • 201 a

Figure 2. Lateral view of a lumbar spine X-ray b Figure 3. a, b. Axial (a) and sagittal revealing an L1 vertebral body compression (b) views of the CT lumbar spine fracture with a more than 50% loss of show loss of height of the L1 vertebral vertebral body height (arrow). In addition to body (arrow, b) with retropulsion of this, superior end plate compression deformity the bony fragments into the adjacent of L2 with an approximately 25–40% loss of spinal canal of up to 9 mm (arrows, vertebral body height is seen. a), causing narrowing. In addition, the CT spine image shows an anterior compression fracture of the L2 vertebral body. The paravertebral soft tissues are lumbar spine surgical decompression unremarkable. was successfully performed. A histo- logical sample of the extracted bony fragments revealed poor bone quality with no evidence of cancer, metasta- sis, osteomyelitis or multiple myelo- ma. Mobilization was started five days after the lumbar surgery. Overall, the patient responded well to the treat- ment, and his functional status signif- icantly improved with rehabilitation and physiotherapy.

Discussion Seizure-induced fracture is an un- common phenomenon, occurring in only 3% of all epileptic patients (7, 10, 11). Kelly reported an incidence of seizure-induced fracture at 2.4%, but Finelli and Cardi reported an in- ture injury that may be delayed by five tion and femoral neck, pelvic, acetabu- cidence as low as 0.3% (6, 7). Most of to seven days in some cases (12). The lar and scapular fractures (1, 4, 7, 11). these fractures occur at night and have most common musculoskeletal injuries Less common fracture sites include the a non traumatic etiology (1, 3, 4). In seen after tonic clonic seizures include facial bones, odontoid process, ribs, 60% of cases, patients remain asymp- compression fractures of the thoracic distal radius and ankle (4, 7, 11, 13). tomatic due to a cloudy sensorium in and lumbar vertebral bodies, humeral Bilateral posterior dislocation of the the post-ictal phase (1, 4). There is a head fractures/dislocations/combined shoulder is highly suggestive of a sei- latency period in the diagnosis of frac- injuries, manubriosternal joint disrup- zure-related injury (7).

202 • September 2011 • Diagnostic and Interventional Radiology Sharma et al. The spine is the most common sei- lying risk factors for seizure-induced any retropulsed bony fragments aris- zure-related fracture site and is critical pathological fractures might be helpful ing from a burst fracture (17). CT can due to the associated irreversible neu- for preventing them in the future. efficiently demonstrate spinal canal rological complications (1, 4). The in- The role of imaging in the diagno- compromise with the sagittal multi- cidence of symptomatic spinal fracture sis of fracture injuries is very critical. planar reconstruction and gives details is 1% after seizure (13). However, the Denis classified burst fractures into five of the retropulsed fragment, which is incidence of asymptomatic spinal frac- categories on the basis of radiographic most commonly a single central frag- tures may be as high as 15–16% as per appearance (19). Type “B”, involving ment (19). CT features demonstrating some studies (8, 13). Compression frac- the superior end plate and retropulsion rotation, fracture and migration of the tures occur more commonly than burst of the superoposterior cortex, is the retropulsed segment correspond to fractures, which account for about 85% most common. Type “C” involves the a poor surgical outcome. CT helps to of seizure-induced fracture injuries in fracture of the inferior end plate only predict outcomes of neurological inju- the spine (9). They cause a decrease and is the rarest. Type “A” is comprised ry by estimating the degree of localized in the height of the anterior aspect of of fractures of both the superior and spinal kyphosis from the fracture. Pa- the vertebral body without severance inferior end plates. Types “D” (burst tients with burst fractures resulting in of the posterior vertebral elements (7, rotation) and “E” (lateral flexion burst) less than 15 degrees of kyphosis have 8, 10, 14). The mechanism of injury are other burst fracture variations. better prognoses and neurological out- of compression fractures involves the However, the current and more sim- comes (19). CT has also been useful for forward flexion of the spine as abdom- plified classification of thoracolumbar the diagnosis of cauda equina root en- inal and paraspinal muscles contract fractures includes three categories (A, B trapment into vertical laminar fracture violently during convulsions (1). Most and C) based on a progressive scale of of the lumbar burst fracture, which is a compression fractures post-seizures are morphological bony damage (19). It is rare complication of the lumbar burst asymptomatic without any major neu- targeted toward ascertaining the stabil- fracture (19). CT is mandatory preop- rological sequelae. They involve the ity of a spinal fracture. An MRI-based eratively to ascertain that pedicles of mid-thoracic spine (T3–T8) where the classification of thoracolumbar inju- the vertebra above and below the burst compression forces concentrate along ries is warranted in the future to bet- fracture site are intact, as they are re- the anterior and middle thoracic ky- ter diagnose discoligamentous injuries quired for screw fixation to stabilize photic spine (1, 4, 6). On the contrary, and predict outcomes of skeletal and the burst fracture (19). burst fractures are far less prevalent associated neurological injuries. However, an MRI of the spine is than compression fractures because Initial spine radiographs might be more useful for detecting soft tissue lig- the axial skeletal contraction forces helpful in the diagnosis of compression amentous injury, particularly the pos- generated after seizures are insufficient fractures. However, spine radiographs terior longitudinal ligament (PLL) and to cause such a massive crush injury may miss 25% of burst fractures, hair- interspinous ligament (ISL) (19). MRI (4). A burst fracture following a seizure line fractures and other non-displaced can demonstrate spinal cord impinge- involves the thoracolumbar vertebral fractures (20, 21). If a screening spine ment, neural compression, extradural junction (T12 to L2), which is a point radiograph reveals a compression frac- hematoma or bulging intervertebral of transition of a rigid kyphotic tho- ture, then a spinal CT must always be discs (20, 22). The PLL rupture is seen racic spine and a more mobile lordotic performed to search for a burst fracture, as a discontinuous black stripe in a sag- lumbar spine (15–17). Gross pathologi- which may compromise the spinal ittal T2W MRI sequence. The ISL injury cal features of burst fractures include canal space (1, 4). Spine radiographs appears as a high intensity signal on a the loss of anterior and posterior verte- give additional information about os- T2W sagittal MRI sequence and is bet- bral body height, comminution of the teoporosis of the spine contributing ter appreciated with MRI than CT (19). superior and/or inferior end plate, ret- to the fracture. Spinal radiographs are Intervertebral disc injury is seen most ropulsion of a bone into the spinal ca- efficacious in the routine follow-up of often in the disc above the fractured nal, increased interpediculate distance, the fracture site post-surgical interven- vertebra as a high intensity signal in vertical laminar fracture, sagittal verte- tion to look for hardware-related com- a T2W MRI sequence, as a rupture of bral body fracture, interspinous widen- plications. a disc into the vertebral body or as a ing and lateral translation/flexion. With the advent of the mutidetector protrusion of the disc into the spinal Certain risk factors predispose an in- CT scan, enabled with advanced refor- canal (19). However, in some cases, dividual to seizure-induced fractures. matting and 3D reconstruction tech- the disc below the fracture level may These include osteoporosis, increased niques, subtle fracture injuries may be involved. The special MRI-STIR se- muscularity, duration of isolated sei- be diagnosed with high confidence. quences are considered superior for zures, repetitive stresses due to recur- CT images can demonstrate end plate detecting spinal cord edema and, rent seizures, osteomalacia due to cal- comminution and sagittal fracture of a therefore, for predicting an imminent cium or vitamin D deficiency, bone vertebral body (19). CT is an excellent spinal cord compression (22). MRI is resorption secondary to primary hy- tool for diagnosing laminar fracture extremely useful for differentiating perparathyroidism or secondary hyper- and fracture/dislocation of the facet neurological injury patterns: injury to parathyroidism, long term use of anti- joints. Type “D” and “E” burst fractures the cord, combined conus medullaris epileptic drugs (valproate, phenytoin, are better seen with high resolution and cauda equina or pure cauda equi- carbamazepine) and long-standing in- CT with multiplanar reconstruction na (19). This may be clinically relevant flammatory bone disease (1, 4, 6, 18). (19). Spinal CT is considered the im- as pure cauda equina compression has Appropriately addressing the under- aging modality of choice to diagnose the best long-term prognosis. Modern

Volume 17 • Issue 3 Seizure-induced lumbar burst fracture associated with conus medullaris-cauda equina compression • 203 MRI scanners are as efficient as CT for can result in a burst fracture. These 12. Kristiansen BN, Cristensen S. Fractures of diagnosing burst fracture-related inju- are common in younger males with the proximal end of the humerus caused ries, such as neural arch fractures and good musculature; they occur more by convulsive seizures. Injury 1984; 16:108–109. wedged compression fractures, which frequently at the time of the first sei- 13. Vasconcelos D. Compression fractures of are best observed on T2W spin echo zure episode and go unnoticed because the vertebrae during major epileptic sei- sequences (19). Dynamic MRI is use- patients cannot localize the area of zures. Epilepsia 1973; 14:323–328. ful for predicting the progressive col- pain. A thorough whole body physical 14. Aboukasm AG, Smith BJ. Nocturnal vertebral compression fracture: a presenting lapse of an already fractured vertebra exam is essential for early diagnosis. A feature of unrecognized epileptic seizures. (23). MRI also gives information about screening thoracolumbar spinal X-ray Arch Fam Med 1997; 6:185–187. the acute/subacute/chronic nature of may be included in the routine workup 15. Wilcox RK, Allen DJ, Hall RM, et al. A dy- vertebral fractures based on the signal of such patients. When a compression namic investigation of the burst fracture intensity of T1W images (20, 22, 23). fracture is diagnosed on a plain film, a process using a combined. Eur Spine J 2004; 13:481–488. Overall, MRI has an increased utility spinal CT should be performed to con- 16. Gräbe RP. 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