Intradural drop metastases in oligodendrogliomas

Oligodendroglioma presenting with intradural spinal metastases: an unusual cause of cauda equina syndrome

We report a 37-year-old man with a primary intracranial oligodendroglioma presenting later with symptomatic multiple cerebrospinal fluid (CSF) intradural drop spinal metastases. This patient initially presented in 2006 with complex partial seizures. Initial histology demonstrated World Health Organization (WHO) grade 2 oligodendroglioma. The patient had further generalised seizures 7 months after initial tumour resection. MRI at that time confirmed tumour recurrence. The patient underwent a repeat craniotomy. Histology showed anaplastic transformation to a WHO grade 3 oligodendroglioma. About 30 months after his initial presentation, the patient developed a focal neurological deficit in the left leg with associated retention of urine. MRI of the neuraxis demonstrated widespread leptomeningeal metastatic drop deposits within the spinal canal. We discuss the mechanisms involved in tumour dissemination throughout the CSF. We also review the relevant literature regarding this phenomenon.

Oligodendroglioma and anaplastic oligodendroglioma:

BACKGROUND

Recent advances that have been made in diagnostic imaging, surgical technique, chemotherapy, molecular biology, and prediction of therapeutic response could have potential impact on the optimal diagnosis and treatment of patients with brain tumors, especially those with oligodendrogliomas. In this article, the topic of oligodendroglioma and anaplastic oligodendroglioma is reviewed, highlighting the new clinical developments.

METHODS

Information for this review was obtained by performing a Medline search for recent references using the term "oligodendroglioma." The bibliographies of papers obtained also were checked for articles that could provide additional understanding of this disease and its current treatment.

RESULTS

The incidence of oligodendroglioma is increasing, most likely due to its improved recognition. Seizures and/or headaches are still common presenting features, and surgery continues to be the primary treatment. Positron emission tomography (PET) and molecular analysis of the surgical specimen are emerging as important diagnostic tools. Patients having either oligodendroglioma or anaplastic oligodendroglioma are likely to respond to chemotherapy. This has had an impact upon the timing of radiation therapy. Survival times are increasing, and patients can now be divided into prognostic subgroups based on the molecular features of their tumors. While procarbazine-CCNU-vincristine (PCV) chemotherapy has been the standard, other agents, notably temozolomide, are currently being tested.

CONCLUSIONS

The algorithm for diagnosing and treating patients with oligodendrogliomas has changed. Neurosurgeons need to be aware of the new developments so they can offer sound advice to their patients.

Current diagnosis and treatment of oligodendroglioma

Object

The strategies used to diagnose and treat oligodendroglial tumors have changed significantly over the past decade. The purpose of this paper is to review the topic of oligodendroglioma, emphasizing the new developments.

Methods

Information was obtained by conducting a Medline search in which the term oligodendroglioma was used. Recent editions of standard textbooks were also studied.

Because of tools such as magnetic resonance imaging, oligodendrogliomas are being diagnosed earlier, and they are being recognized more frequently histologically than in the past. Seizures are common in these patients. Functional mapping and image-guided surgery may now allow for a safer and more complete resection, especially when tumors are located in difficult areas. Genetic analysis and positron emission tomography may provide data that supplement the standard diagnostic tools. Unlike other low-grade gliomas, patients in whom residual or recurrent oligodendroglioma (World Health Organization Grade II) is present may respond to chemotherapy. Although postoperative radiotherapy prolongs survival of the patient, increasingly this therapeutic modality is being delayed until tumor recurrence, especially if a gross-total tumor resection has been achieved. Oligodendrogliomas are the first type of brain tumor for which “molecular” characterization gives important information. The most significant finding is that allelic losses on chromosomes 1p and 19q indicate a favorable response to chemotherapy.

Conclusions

Whereas surgery continues to be the primary treatment for oligodendroglioma, the scheme for postoperative therapy has shifted, primarily because of the lesion's relative chemosensitivity. Molecular characterization of oligodendrogliomas may become a standard practice in the near future.