Do prophylactic steroids prevent chemical meningitis in surgery for epidermoid cysts? Case report and literature review

INTRODUCTION

Epidermoid cysts (EC) are slow-growing lesions that account for less than 1% of all spinal lesions.[4] Notably, only 80 cases of intramedullary EC have been reported in literature.[5] At surgery, EC contain flaky material with a thin diaphanous wall, and leakage of its keratinous contents may cause postoperative chemical meningitis (e.g., symptoms including fever, headaches, and/or meningism),[1] that O’Malley and Haynes, cited as occurring in 0.3–5.5% of such cases.[8] Although steroids are often administered in an attempt to prevent possible chemical meningitis/neurological sequelae, there are no guidelines for their prophylactic use.[1,3,6]

Here, we present a 44-year-old patient who underwent surgery for a thoracic intramedullary EC, who was given a prophylactic course of oral steroids postoperative operatively and did not develop chemical meningitis.

CASE DESCRIPTION

Thoracic MR

The thoracic spine MRI demonstrated a well demarcated, 1.3 × 0.9 × 2.0 cm (TV × AP × CC) ovoid intramedullary lesion in the dorsal cord at T3/4; it expanded and displaced the cord to the left. There was also a smaller, caudal, and exophytic component. On the MR, the lesion was solid, homogeneous, and hypointense on T1-weighted images, hyperintense on T2-weighted images and did not enhance with gadolinium [Figure 1a and b]. It also demonstrated restricted diffusion (e.g., on diffusion weighted studies), while spectroscopy identified water and lactate within the lesion [Figure 1c].

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Figure 1:: Preoperative magnetic resonance imaging of the thoracic spine shows a T3/4 intradural, intramedullary cyst. (a) On T2-weighted MRI, the cyst is hyperintense to spinal cord, with cord fibers splayed over the lesion. (b) There is no enhancement of the cyst with gadolinium. (c) The ADC map MRI, confirms restricted diffusion.

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Surgery

A T2-T3 laminectomy with laminoplasty was performed. Once the dura was opened, the intramedullary cyst was immediately identified coming to the cord surface on the right; it is exophytic component was glistening white and thin walled [Figure 2a and b]. A plane was developed between cyst and cord, enabling meticulous resection while avoiding spillage of cyst contents into the subarachnoid space.

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Figure 2:: Intraoperative photos. (a) Intramedullary cyst with an exophytic component visualized on opening the intact spinal dura and arachnoid. Nerve roots are seen splayed laterally (arrow). (b) Cyst contents were flaky and “pearl-like” in appearance.

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Histology

The histologic examination confirmed an EC lined with a thin layer of keratinizing stratified squamous epithelium on a fibrocollagenous base. It contained abundant anucleate squames. No dermal skin appendages were identified in the wall of the cyst and there were no luminal hair shafts [Figure 3].

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Figure 3:: A low power photomicrograph of the cyst wall showing a stratified squamous epithelial lining (>), on a dense fibrocollagenous base (O) and anucleate squames within the lumen (*). No skin adnexae were identified (hematoxylin and eosin, ×15).

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DISCUSSION

Surgical resection of ECs may result in intraoperative rupture with its cyst contents (cholesterol, keratin, and lipid) spilling into the subarachnoid space, resulting in a chemical meningitis.[1,2,6] Such a use of steroids for prophylaxis is widely accepted.[2,3,6]

The authors reviewed three studies involving a total of 34 patients undergoing surgery for 14 cranial (posterior fossa), and 20 spinal ECs. Of the 24 patients given prophylactic steroids (most commonly intrathecal hydrocortisone irrigation; 22 cases), 13 included the posterior fossa and 11 included the spine. Only two patients developed fever or symptoms of meningism postoperatively; however, it is not clear whether one of these had been previously treated for chemical meningitis. The second patient had experienced two bouts of preoperative chemical meningitis [Table 1]. In 1967, Cantu and Ojemann reported the first successful management of a patient given prophylactic oral methylprednisolone for 8 days following surgery for a posterior fossa EC.[3] Berger et al. also managed 11 patients following resection of a posterior fossa EC.[2]

Table 1:: Summary of literature review for the use prophylactic steroids to prevent chemical meningitis.

In the randomized control trial, Kapoor et al., 2003, 11 of the 20 patients with spinal ECs, treated with prophylactic steroids (e.g., intraoperative irrigation of the intrathecal space with 0.01% hydrocortisone mixed with normal saline), demonstrated no postoperative signs of fever or meningismus. The nine patients in the control group (without intraoperative hydrocortisone irrigation) exhibited symptoms/signs of chemical meningitis (e.g., postoperative fever [P< 0.01], and seven exhibited frank “meningismus” [P < 0.01]).[6] Although, the number of patients included in this randomized controlled trial was small, a “trend” regarding the potential benefit of prophylactic treatment for patients undergoing surgery for EC with intraoperative steroids was demonstrated.

CONCLUSION

The patient in the current case report, following surgery for an intramedullary EC, was given a postoperative, prophylactic course of oral dexamethasone that avoided postoperative meningitis/meningismus. A cursory review of literature showed Level II evidence that administrating perioperative/ postoperative steroids prophylactically in patients with spinal ECs may help prevent postoperative chemical meningitis.[7]