Primary brain tumors and posterior reversible encephalopathy syndrome

Acute Neurological Complications of Brain Tumors and Immune Therapies, a Guideline for the Neuro-hospitalist

PURPOSE OF REVIEW

Patients with brain tumors presenting to the emergency room with acute neurologic complications may warrant urgent investigations and emergent management. As the neuro-hospitalist will likely encounter this complex patient population, an understanding of the acute neurologic issues will have value.

RECENT FINDINGS

We discuss updated information and management regarding various acute neurologic complications among neuro-oncology patients and neurologic complications of immunotherapy. Understanding of the acute neurologic complications associated with central nervous system tumors and with common contemporary cancer treatments will facilitate the neuro-hospitalist management of these patient populations. While there are aspects analogous to the diagnosis and management in the non-oncologic population, a number of unique features discussed in this review should be considered.

Neurological complications of systemic tumor therapy

The treatment of malignant tumors has considerably improved in recent years, and also the number of "long term cancer survivors" is increasing.The spectrum of anti-tumoral agents is increasing at a fast pace and in addition to conventional therapies such as surgery, radiotherapy, and chemotherapy, new drugs with entirely new mechanisms are appearing. Side effects of old and new drugs can affect the central and peripheral nervous system, the neuromuscular junction, and muscle. These side effects often have to be distinguished from other causes and need neurological expertise. Although the majority of patients still receive conventional therapies, several new strategies such as immune therapies are being implemented. These drugs have also drug specific side effects, which do not always follow the classical principles of "toxicity."This review focuses on the well-known and described side effects of conventional cancer therapies and adds new observations on new drugs.

Neurological complications of new chemotherapy agents

This last decade has yielded more robust development of cancer treatments and first-in-class agents than ever before. Since 2006, nearly one hundred new drugs have received regulatory approval for the treatment of hematological and solid organ neoplasms. Moreover, older conventional therapies have received approval for new clinical indications and are being used in combination with these newer small-molecule targeted treatments. The nervous system is vulnerable to many of the traditional cancer therapies, manifesting both already well-described acute and chronic toxicities. However, newer agents may produce toxicities that may seem indistinguishable from the underlying cancer. Early recognition of neurotoxicities from new therapeutics is vital to avoid irreversible neurological injury. This review focuses on cancer therapies in use in the last 10 years and approved by the FDA from January 2006 through January 1, 2017.

Development of a DIPG Orthotopic Model in Mice Using an Implantable Guide-Screw System

Objective

In this work we set to develop and to validate a new in vivo frameless orthotopic Diffuse Intrinsic Pontine Glioma (DIPG) model based in the implantation of a guide-screw system.

Methods

It consisted of a guide-screw also called bolt, a Hamilton syringe with a 26-gauge needle and an insulin-like 15-gauge needle. The guide screw is 2.6 mm in length and harbors a 0.5 mm central hole which accepts the needle of the Hamilton syringe avoiding a theoretical displacement during insertion. The guide-screw is fixed on the mouse skull according to the coordinates: 1mm right to and 0.8 mm posterior to lambda. To reach the pons the Hamilton syringe is adjusted to a 6.5 mm depth using a cuff that serves as a stopper. This system allows delivering not only cells but also any kind of intratumoral chemotherapy, antibodies or gene/viral therapies.

Results

The guide-screw was successfully implanted in 10 immunodeficient mice and the animals were inoculated with DIPG human cell lines during the same anesthetic period. All the mice developed severe neurologic symptoms and had a median overall survival of 95 days ranging the time of death from 81 to 116 days. Histopathological analysis confirmed tumor into the pons in all animals confirming the validity of this model.

Conclusion

Here we presented a reproducible and frameless DIPG model that allows for rapid evaluation of tumorigenicity and efficacy of chemotherapeutic or gene therapy products delivered intratumorally to the pons.

Posterior Reversible Encephalopathy Syndrome Resolving Within 48 Hours in a Normotensive Patient Who Underwent Thoracic Spine Surgery

Posterior reversible encephalopathy syndrome (PRES) usually manifests with severe headaches, seizures, and visual disturbances due to uncontrollable hypertension. A patient (age in the early 60s) with a history of renal cell cancer presented with lower-extremity weakness and paresthesias. Magnetic resonance imaging (MRI) of the thoracic spine revealed a T8 vertebral body metastatic lesion with cord compression at that level. The patient underwent preoperative embolization of the tumor followed by posterior resection and placement of percutaneous pedicle screws and rods. Postoperatively, the patient experienced decreased visual acuity bilaterally. Abnormal MRI findings consisted of T2 hyperintense lesions and fluid-attenuated inversion recovery changes in both occipital lobes, consistent with the unique brain imaging pattern associated with PRES. The patient’s blood pressure was normal and stable from the first day of hospitalization. The patient was kept on high-dose steroid therapy, which was started intraoperatively, and improved within 48 hours after symptom onset.