Recurrent symptomatic pleural effusion from a syringopleural shunt

Abstract

A patient with a syringopleural shunt with dyspnea and cough was found to have a recurrent large pleural effusion. Computed tomography of the thorax revealed the syringopleural shunt catheter abutting the pleural effusion, and beta-2 transferrin was detected in the pleural fluid, suggesting that the recurrent symptomatic pleural effusion was secondary to the syringopleural shunt. Physicians should be cognizant of this potential long-term complication of syringopleural shunts. Management includes revising the shunt with a programmable device or converting it to a syringoperitoneal or syringoarachnoid shunt.

Syringopleural shunts are used to decompress the syrinx in syringomyelia patients, but the long-term effects are not well documented and can be harmful. Recurrent, symptomatic pleural effusions from syringopleural shunts may lead to unnecessary diagnostic tests and iatrogenic harm or infection. They may also lead to the development of multidrug resistance through inappropriate antibiotic stewardship, while delaying more definitive treatment.

CASE REPORT

A 35-year-old man with a history of paraplegia secondary to thoracic syringomyelia with a syringopleural shunt placed 6 years prior, as well as sacral decubitus ulcers and chronic osteomyelitis requiring left hip disarticulation, presented with sepsis. He had persistent fever, leukocytosis, and tachycardia. At the time, he was being treated with antibiotics for chronic osteomyelitis. Computed tomography (CT) of the abdomen and pelvis with contrast revealed a septated abscess adjacent to the left acetabular roof while incidentally identifying a loculated, right pleural effusion, which was then confirmed on CT thorax with contrast (Figure 1a). The abscess was too small to drain and decreased in size on repeat imaging while on the same antibiotics. Blood and urine cultures were negative.

Figure 1.

(a) CT of the thorax with contrast demonstrating a moderate to large loculated right-sided pleural effusion that had increased from previous images. Atelectatic changes are seen in the right upper lobe and atelectatic changes with fibrosis and mild bronchiectatic changes are seen in the right lower lobe. (b) MRI of the thoracic spine without contrast demonstrating cystic changes within the spinal cord at T7–T11 with cord atrophy in the superior region.

During the course of his septic workup, the patient began to report worsening dyspnea. Thoracentesis was performed, yielding 750 mL of clear fluid. Pleural fluid studies were consistent with a transudative etiology and fluid cultures were negative. His fever eventually resolved without additional treatment and was likely due to transient bacteremia from his septated abscess.

Upon further chart review, the patient was found to have had a right-sided pleural effusion for multiple years with previous thoracenteses resulting in negative infectious workups. Upon suspicion that the pleural effusion was secondary to the syringopleural shunt, the pleural fluid was tested for beta-2 transferrin, which was detected, indicating the presence of cerebrospinal fluid (CSF). The patient reported five revisions prior to the last shunt revision 5 years prior. CT of the thorax with contrast showed appropriate placement of the syringopleural shunt, and magnetic resonance imaging (MRI) of the thoracic spine without contrast showed no recurrence of syringomyelia (Figure 1b). Since the fluid was transudative and cultures were negative, this pleural effusion was likely secondary to his syringopleural shunt draining into the pleural space without resorption of fluid. Nine days following thoracentesis, the patient began experiencing increasing dyspnea again, and repeat chest x-ray demonstrated a reaccumulation of pleural fluid. He was to follow-up with neurosurgery to discuss shunt revision options with a programmable valve.

DISCUSSION

Shunt systems are used to divert CSF away from the syrinx cavity and improve compressive neurologic symptoms, usually after all other medical interventions have failed.¹ Different shunts have been used in the management of syringomyelia, although the indications are not well defined.² Short-term complications are usually minimal, but limited data are available regarding long-term complications. Due to the lack of widely accepted guidelines, shunt placement is considered controversial.³

As noted in the current case, syringopleural shunts divert CSF to the pleural cavity. Most fluid is reabsorbed by the pleura, but small pleural effusions can be visible on imaging.⁴ A retrospective study of 26 cases of syringomyelia patients with a syringopleural shunt reported no severe complications; however, the follow-up period was only 27 months.² A longer study with 19 patients and a mean follow-up period of 37.5 months reported only one significant complication of meningitis.¹ The longest study had a mean follow-up period of 9 years in 21 patients with syringopleural shunts and noted complications such as shunt obstruction, shunt migration, neurological deficits, tethered spinal cord, spinal instability, and excessive CSF drainage.^5,6 There were two reports of asymptomatic pleural effusions.⁶ Our case is the second documented report of a patient developing significant symptomatic recurrent pleural effusion as a result of a syringopleural shunt placement.⁷ Postulated mechanisms for this pleural malabsorption are impaired absorptive capacity from previous damage (i.e., prior infection or chronic exposure to CSF) or excessive drainage of CSF into the pleural space.⁴

A more recent case report detailed the development of intracranial hypotension in a middle-aged man with syringopleural shunt placement for a thoracic posttraumatic syrinx. The shunt was revised to slow the rate of CSF drainage by placing a programmable valve.⁸ This case demonstrates that some of these patients may require shunt revisions, as recommended for our patient. Some people require further intervention such as craniovertebral decompression despite having a functioning shunt.^5,6,8

Syringopleural shunts are generally viewed as safe alternatives to syringoperitoneal shunts. Although retrospective studies looking at these shunts are available, long-term complications are not fully established and are extrapolated from ventriculopleural shunt studies, which are also uncommon.⁶ In the case above, this patient had multiple thoracenteses performed over 6 years after placement of the syringopleural shunt due to the lack of familiarity with this device and its possible complications. More definitive treatment with neurosurgery was needed.