Abstract

We present a case of post-operative iatrogenic quadriplegia, which occurred after subtotal parathyroidectomy. This patient was on long-term hemodialysis for 7 years. The need of prolonged neck extension for this procedure was probably the main risk factor for the spinal cord injury. Systemic hypotension which contributed to the injury in this case, should be anticipated and promptly treated to prevent further damage. Spinal deformities associated with end-stage renal disease may make such patients more susceptible. Since appropriate precautions against potential neurologic damage can be undertaken, we suggest that evaluating carefully for the pre-existing spinal stenosis before a procedure requiring prominent and prolonged hyper-extension of the neck, especially in long-term hemodialysis patients is of paramount importance.

Keywords

quadriplegia; parathyroidectomy; renal dialysis;

1. Introduction

Post-operative quadriplegia after surgery is an extremely rare but distressing complication. Previous reports have suggested that mechanical or ischemic injury is ascribed to be the most common etiology.1, 2, 3, 4, 5 Amyloidosis-induced destructive spondyloarthropathy (DSA) resulting from long-term hemodialysis, prolonged extreme neck extension and pre-existing spinal abnormalities are the predisposing factors.³ To the best of our knowledge, only two cases of post-operative quadriplegia after parathyroidectomy in uremic patients were reported in the literature.³ We present a uremic case who sustained iatrogenic quadriplegia following parathyroidectomy in the absence of preceding abnormal neurological findings. The mechanism of spinal cord injury and suggestive management are discussed.

2. Case report

A 60-year-old man of chronic glomerulonephritis with hemodialysis history for 7 years was scheduled for total parathyroidectomy and autotransplantation because of secondary hyperparathyroidism (iPTH = 1598 pg/ml) associated with hypercalcemia (Ca = 11.3 mg/dl) and hyperphosphatemia (I.P. = 5.4 mg/dl) that was resistant to medical treatment. His noticeable past medical history was hypertension. A few months before this admission, he complained of pruritus, muscle weakness, and non-specific soreness around the shoulders. Before the surgery, the patient had no history of neck trauma, weakness of the limbs or sensory impairment and the neurological examination was normal. Therefore no preoperative X-ray of the cervical spine was taken. Anesthesia was induced with intravenous thiopental sodium, fentanyl and cis–atracurium, and maintained with isoflurane in O₂. Intubation was smoothly performed without excessive cervical extension. The patient was placed in the supine position with a pillow placed under his shoulders to facilitate neck extension. Prolonged hypotension with systolic blood pressure around 60–85 mmHg for about 60 min was noted during operation in spite of a total administration of ephedrine 56 mg given intermittently. The whole surgical procedure took about 5 hours. The patient was extubated immediately after the operation and he was transferred to the post-operative recovery room for close care. Unfortunately, the patient showed progressive weakness of both upper and lower extremities, especially on the left side. Quadriplegia (right upper limb power 4/5; left upper limb power 3/5; right lower limb power 2/5; left lower limb power 1/5) was contemplated. There was no dysarthria, conscious change, headache, or nausea/vomiting. The consulting neurologist was of the opinion that cervical spine lesion or acute cerebral infarction was the culprit. The brain computed tomography (CT) showed no intracerebral hemorrhage. A magnetic resonance imaging (MRI) of the cervical spine disclosed an extra-dural fusiform mass lesion in the ventral spinal canal with obvious cord compression at the level of C4–C6. The possibility of pre-existing discitis and herniated intervertebral disc, mainly at C5–6 and less at C4–5 which were exaggerated by surgical positioning of neck should be ruled out (Fig. 1). Under the impression of C5–6 herniated intervertebral disc with quadriplegia, the patient then underwent emergent three-level (C4–C6) disectomy and fusion with cage. The surgical and pathological findings revealed degenerative intervertebral discs. Post-operative improvement was fine, with right upper limb power 5/5; left upper limb power 5/5; right lower limb power 4⁄5; and left lower limb power 3/5.

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Fig. 1. (a) T2-weighted sagittal MRI scan of the cervical spine shows extra-dural fusiform mass lesion in the ventral spinal canal with obvious cord compression at the level of C4–C6, mainly at C5–6 and less degree at C4–5. Multiple disc bulging seen. (b) Axial image shows encroachment of the spinal canal.

3. Discussion

There were only two reported cases with long-term hemodialysis who sustained iatrogenic tetraparesis (26 and 27 years, respectively) related to prolonged neck hyper-extension while undergoing parathyroidectomy.³ We hereby report the first similar case in Taiwan who had been subjected to hemodialysis for 7 years with asymptomatic spinal disease.

Post-operative quadriplegia, with incidence not yet known, is an extremely rare complication of surgery.1, 2, 3, 4, 5 Possible mechanisms proposed to explain the cause of this complication include ischemic damage because of overstretching of the cervical spinal cord,⁴ occlusion of the vertebral arteries related to extreme head rotation,¹ and direct compression of the spinal cord in the presence of a pre-existing cervical stenosis.⁵ The damage from primary and secondary insults of spinal cord injury can result in various hemodynamic alterations. Systemic hypotension refractory to high dose ephedrine stood out as the only sign in our patient during surgery. This might be a warning sign of neurogenic shock complicated by spinal cord injury at or above the level of T6, becuase of sympathetic denervation.⁶ We should identify and remove the triggering offender as soon as possible. Besides, the most recent guidelines for handling spinal cord injury suggest that the blood pressure should be maintained at a mean arterial pressure of 85–90 mmHg to ensure adequate spinal cord perfusion.⁷ To mitigate the harmful effects of shock in patients with spinal cord injury, fluid resuscitation is primarily used to maintain perfusion. When intravenous fluids fail to reverse shock or signs of volume overload are present, vasopressors should be considered.⁸ Somatosensory evoked potentials (SSEP) monitoring helps reduce the incidence of devastating neurological injury during cervical procedures and should be considered as an adjunct of the surgery.⁹

Patients with chronic renal failure are prone to spinal degenerative disease induced by dialysis-related amyloidosis. Besides, chronic overproduction of parathyroid hormone in patients with renal failure contributes to a spectrum of bone diseases (e.g. osteitis fibrosa cystica and mixed uremic osteodystrophy).¹⁰ DSA has been used to describe a process occurring in hemodialysis patients, which affects primarily the spinal joints and intervertebral discs. DSA is seen with increasing frequency in consequence of amyloid deposition.¹¹ Cervical discs are most susceptible to β₂-microglobulin amyloid deposition in the vertebral column, although patients often remain asymptomatic.¹² But in our case, the post-operative pathological report and MRI images showed no evidence of possible involvement of amyloidosis or osteitis fibrosa cystica and mixed uremic osteodystrophy.

Brieg has shown that the cervical spinal cord increases in length up to 2.8 cm when the neck moves from full extension to full flexion and that the location of the maximum change in length is approximately at the C-5 level.¹³ Spine extension increases cervical cord diameter and induces the folding of the ligamentum flavum, which may exert pressure on the cord and on the posterior longitudinal vessels.³ Cervical spine injury with unstable spinal column becuase of positioning may occur in the hemodialysis patient. In these patients, subsequent MRI and CT imaging studies demonstrated significant pre-existing spinal stenosis. If an intraspinal lesion is identified, immediate decompression may provide partial or complete recovery, depending on the timing and the extent of the injury.¹⁴

The development of quadriplegia in our hemodialysis patient after parathyroidectomy was most likely caused by cervical spine hyper-extension during positioning in the presence of severe cervical spine spondylosis. This event emphasized the fact that, although cervical stenosis was not found before the operation, the risk of spinal cord injury should be suspected based on the knowledge that the patient was under hemodialysis.

By this painful experience, we have the following suggestions: 1) the cervical spine should be carefully evaluated before endotracheal intubation, especially in the hemodialysis patient; 2) attempt should be made to avoid neck hyper-extension during surgery in such patient; 3) blood pressure should be maintained at a mean arterial pressure of 85–90 mmHg to ensure adequate spinal cord perfusion to prevent neurogenic shock; 4) SSEPs and MEP may be considered in neuromonitoring to assess patient’s spinal cordfunction during operation; 5) neurologic examination should be routinely performed in the recovery room; and 6) if significant neurologic deficits are identified, investigative workup should not be delayed as early decompression appears to offer the most reliable and favorable outcomes.

In conclusion, anesthesiologists should keep in mind that long-term dialysis patients are prone to cervical spine injury related to prolonged neck extension. Careful history taking and thorough neurological examination should be mandatory. After the underlying cervical spine pathology is suspected, further image study should be performed and neurologist and/or neurosurgeon must be consulted. Intra-operative MEP and SSEP monitoring may be effective in preventing from serious spinal cord injury.