Intramedullary and Extramedullary Cervical Neurenteric Cyst Requiring Fixation and Fusion

Bilobed intramedullary and extramedullary bronchogenic cyst of the conus medullaris: illustrative case

BACKGROUND

Spinal bronchogenic cysts are rare nonneoplastic congenital variants of neurenteric cysts. The natural history and surgical management of these lesions are poorly understood.

OBSERVATIONS

A 25-year-old male presented with progressive back pain and bilateral lower limb sciatica of 6 months’ duration. He had undergone subtotal resection of an intramedullary bronchogenic conus medullaris cyst 5 years prior. Magnetic resonance imaging revealed a recurrent bilobed intramedullary and extramedullary conus medullaris cystic lesion. The authors resected the lesion via a posterior approach with the aid of intraoperative neuromonitoring. Gross total resection was precluded by the tightly adherent nature of the cyst and the fact that stimulation of a residual intramedullary portion of the lesion evoked external anal sphincter responses.

LESSONS

This is the first reported case of a bilobed intramedullary and extramedullary bronchogenic cyst of the conus medullaris. This unique case lends insight into the poorly defined embryogenesis of bronchogenic cysts by favoring the split notochord syndrome theory rather than the ectopic ectoderm proposal. The importance of neuromonitoring when resecting these tightly adherent lesions is demonstrated. Finally, although the secretory nature of these lesions portends a tendency for cyst reaccumulation, it is imperative to recognize that this is usually a slow process.

[Nonneoplastic lesions of the spinal canal]

Numerous vascular, inflammatory, degenerative and tumorous lesions of the spinal canal can cause paraplegic symptoms. In addition to the neurological examination and the leading symptoms, the first topographical classification of the (suspected) disease is essential for further diagnostics. Hence, high-resolution magnet resonance imaging (MRI) is the gold standard for the majority of questions. To avoid diagnostic and therapeutic mistakes, differentiation of intraspinal tumors from tumor-like (nonneoplastic) lesions is indispensable, which is often only possible after follow-up imaging or surgical exploration.

Management of a cervical spine neurenteric cyst via an anterior surgical approach: illustrative case

BACKGROUND

Central nervous system neurenteric cysts (NCs) represent a rare entity thought to arise from failure of the separation of endodermal and neuroectodermal elements during week 3 of embryogenesis. They account for 0.7–1.3% of all spinal cord lesions and are typically intradural extramedullary lesions located near the cervicothoracic junction. Most NCs are associated with multisystem malformation disorders, making a solitary extramedullary NC a rare entity.

OBSERVATIONS

A 45-year-old man presented with progressive right lower-extremity weakness and an inability to walk. Cervical spine magnetic resonance imaging demonstrated an approximately 1.6 × 1.1 × 2.7–cm, T2 hyperintense, nonenhancing, intradural, extramedullary cystic lesion at the level of C6–7 eccentric to the right with atrophy of the spinal cord. An anterior surgical approach was used for resection of the cyst in totality with C6–7 corpectomies and anterior plating and fixation from C5 to T1. Postoperatively at 1 month, the patient denied any significant neck or arm pain and demonstrated improving right lower-extremity strength, allowing some funcitonal independence.

LESSONS

A solitary, extramedullary cervical NC is a rare entity, with a posterior surgical approach for resection primarily described in the literature. The authors present anterior corpectomy and plating with fixation as a viable surgical approach for this rare pathology.

Intramedullary Masses of the Spinal Cord: Radiologic-Pathologic Correlation

Spinal cord tumors are a challenge for patients and neurosurgeons because of the high risk of neurologic deficits from the disease process and surgical interventions. Spinal cord tumors are uncommon, and approximately 2%-3% of primary intra-axial tumors of the central nervous system occur in the spinal cord. Primary intra-axial tumors are usually derived from neuroepithelial tissue, especially glial cells. This often leads to a classic intramedullary mass differential diagnosis of ependymoma or astrocytoma, which together constitute up to 70% of spinal cord tumors. For example, ependymomas occur predominantly in adults, and astrocytomas (specifically pilocytic astrocytomas) occur predominantly in children. While that is an excellent starting point, in order to refine the differential diagnosis, the authors review the radiologic-pathologic features of specific neoplastic categories and entities recognized by the World Health Organization (WHO) in the 2016 WHO Classification of Tumours of the Central Nervous System and a few additional congenital-developmental entities. Radiologists can add value by providing a reasonable preoperative differential diagnosis for the patient and neurosurgeon, in many cases by favoring the most common conditions, and in other cases by identifying radiologic features that may point toward a less common entity. Some of the less common entities include intramedullary myxopapillary ependymoma, spinal subependymoma, and spinal hemangioblastoma. Whenever possible, the characteristic imaging features and locations of these tumors are explained or traced back to the underlying cell of origin and findings seen at histopathologic examination.See discussion on this article by Buch.

Changes in Cervical Neurenteric Cyst Size

Spinal neurenteric cysts are rare congenital anomalies and the natural history of the cyst is not fully understood. We evaluated a case of spontaneous absorption of a cyst. The patient was a 5-year-old boy who had experienced pain in the bilateral upper extremities 3 days before his admission. Neurological examination revealed severe motor weakness of the upper extremities and mild motor weakness of the lower extremities. Magnetic resonance imaging (MRI) revealed an extramedullary cystic lesion with a fluid-fluid level in the cervical region. One week later, the pain spontaneously improved with bed rest, and the patient showed good neurological recovery. MRI performed 6 months later revealed spontaneous reduction of the cyst. Enlargement and contraction of the cyst were observed over 3 years on MRI. Since the size of the cyst changes, MRI should be performed annually for patient follow-up.

[Spinal cysts : Diagnostic workup and therapy]

CLINICAL ISSUE

Spinal cysts can be classified as meningeal, not meningeal, and tumor-associated cysts. Due to the widespread availability of high-resolution computed tomography and magnet resonance imaging, spinal cysts can be detected with high sensitivity these days. Concerning the variety of potential cystic differential diagnoses, a precise classification is difficult and can often only be realized after surgical inspection or histological examination.

PRACTICAL RECOMMENDATIONS

Spinal cysts are generally incidental findings during a routine diagnostic workup and need no further therapy. Surgical treatment can be necessary if the spinal cyst reaches a certain size and causes neurological symptoms due to the compression of the spinal cord or the nerve root.