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A hidden injury
  1. C U Dussa,
  2. B M Soni
  1. Regional Spinal Injuries Centre, Southport District General Hospital, Southport, UK
  1. Correspondence to:
 Mr C U Dussa
 Flat 9-C, Y-Block, Southport District General Hospital, Town Lane, Kew, Southport PR8 6PN, UK; dussacu1msn.com

Abstract

Transverse sacral fractures associated with cauda equina syndrome are uncommon lesions and often missed at the time of presentation. This case report highlights the benign presentation and the unpleasant outcome of such an injury.

  • sacrum
  • transverse fracture
  • cauda equina syndrome

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A 65 year old woman fell on the ground from a standing position and landed on her bottom. She was unable to get up and was brought to the accident and emergency department by ambulance. She complained of pain in her hips. She was tender over her pubic ramus on the left side. Both the hip joints, dorsal and lumbar spine did not reveal any tenderness or deformity. Neurological examination did not show any abnormality. Radiographs showed fractures of her left superior and inferior pubic ramus (fig 1). The dorsal and lumbar spine radiograph did not show any fractures. She was admitted to the orthopaedic ward for pain relief and mobility assistance.

Figure 1

Radiograph of the pelvis showing the fracture of the superior and inferior pubic ramus on the left side.

While on the ward she developed urinary retention that was relieved by intermittent catheterisation. After three days, although her mobility improved because of pain relief, her bladder function did not improve and she needed an in-dwelling catheter. Faecal incontinence was also noted at the same time. A thorough examination of the spine was done that revealed some tenderness in the middle of sacrum. Motor examination showed weakness of the plantar flexors of ankle and toes. Absence of perianal sensation was noted. Rectal examination showed lax anal sphincter and absent anal reflex. Radiography of the sacrum showed a transverse fracture of the sacrum with severe angulation (fig 2). She was shifted to the specialised centre for rehabilitation. Her motor function improved as a result of improved muscle strength, perianal sensation was still numb, and her bladder function improved, as she was able to hold the urine for short periods, and bowels evacuated spontaneously after retraining four months after the injury.

Figure 2

Radiograph of the sacrum lateral view—showing the transverse sacral fracture involving the body of the S2 sacral body with angulation.

DISCUSSION

Richarand, a French surgeon, was the first person to report a sacral fracture.1 The position of the sacrum and the strength of the bone make it less vulnerable to fracture. Their occurrence may be isolated or may be associated with other obvious fractures, which easily catch the attention of the treating doctor.2,3 The neurological deficit being subtle adds to the delay in diagnosis.1,4 Pohlemann et al call it “hidden injury”.5

The mode of injury may be either a fall from a height6 or an automobile accident.1 The reported incidence is 0.3% of isolated transverse fractures of sacrum of a series of 667 spinal fractures over a 12 year period.7

It is well known that sacral fractures can easily be missed on conventional radiographs. Most of the sacral radiographs taken in the casualty department are of poor quality.6 A lateral view should be asked for in suspected cases.3,6,8,9 Superimposition of the bowel loops on the sacrum, superimposition of the bones especially in the upper sacrum because of kyphosis, osteoporosis in the elderly population, and most importantly the lack of suspicion of the fracture6 are proposed reasons for delay in diagnosis. Fracture of the transverse process of L5 should raise a strong suspicion of sacral fracture.10 There was a 33% increase in the observed rate of sacral fracture11 with the use of computed tomography. Magnetic resonance imaging can show the neural compression and sagittal view may aid in the diagnosis of fracture.3

The presence of perineal ecchymosis and a contusion on the base of spine apart from the tenderness is the indirect evidence of sacral fractures. Urethral injury may be present concomitantly. The incidence of neurological deficit quoted in the literature is 56.7% to 63.6%.8,11,12 Bladder,1,3,6,8,10,12–16 followed by bowel and changed sexual function1 are problems in the order of frequency that occur in a transverse sacral fracture. Neurological deficit is of the lower motor neuron type involving the nerve roots from S1 to S4. Though these fractures can be treated conservatively or by surgical decompression10 the neurological recovery especially of the pelvic viscera is unpromising1,3 and can take as long as 1.5 to 2 years.11

In conclusion, a transverse sacral fracture with cauda equina injury is a very rare injury and is commonly missed. The mode of injury, a strong clinical suspicion8 and examination of perineum and per-rectal examination can give important clues to the underlying fracture. In case of suspected sacral fracture, computed tomography is advisable. Complete recovery is very unpredictable. A missed injury may have serious legal consequences.

REFERENCES

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