10. Brain Tumors (Mass Effect, Herniation, and Related Neuro-Oncologic Emergencies)

Quick Recap

Neurology System, Protocol 10/12. Covers primary/metastatic brain tumor-related mass effect and edema, herniation syndrome recognition, and the closely related neuro-oncologic emergency of malignant spinal cord compression. Nests with the Raised ICP protocol for full tiered ICP management.

1. Scope

Brain tumors (primary or metastatic) become ICU-relevant through: (1) peritumoral vasogenic edema causing mass effect/raised ICP, (2) acute herniation, (3) tumor-associated seizures, (4) obstructive hydrocephalus (posterior fossa/intraventricular lesions), (5) tumor hemorrhage, and (6) related neuro-oncologic emergencies (malignant spinal cord compression, immunotherapy-related neurotoxicity). This protocol addresses the ICU stabilization principles; definitive oncologic treatment (surgery, radiotherapy, chemotherapy) is directed by neuro-oncology/neurosurgery.

2. Pathophysiology

Brain tumors cause vasogenic edema (distinct from the cytotoxic edema of ischemic stroke) via tumor-associated disruption of the blood-brain barrier, with fluid accumulating preferentially in white matter surrounding the mass. This edema, more than the tumor mass itself, is often the dominant driver of symptoms and is characteristically STEROID-RESPONSIVE — a key distinguishing feature from most other causes of raised ICP covered elsewhere in this system, where steroids play no significant role (compare to Raised ICP protocol's tiered algorithm, none of which centers on corticosteroids).

Mass effect follows Monro-Kellie principles (see Raised ICP protocol) but the SPACE-OCCUPYING, focal nature of tumors makes localized herniation syndromes especially relevant.

3. Herniation Syndrome Recognition (Clinical Emergency Pattern Recognition)

Recognizing evolving herniation clinically, before it is complete, is the single most time-critical skill in this protocol. Classic warning signs across syndromes: new/worsening headache, declining consciousness, pupillary changes, and abnormal posturing — any combination should trigger immediate action (osmotherapy + emergent imaging + neurosurgery notification) rather than awaiting confirmatory imaging.

• Uncal (lateral transtentorial) herniation: medial temporal lobe pushes through the tentorial notch, compressing CN III -> ipsilateral pupillary dilation ("blown pupil") is the classic early sign, followed by contralateral hemiparesis (or, with further progression, ipsilateral hemiparesis from Kernohan's notch phenomenon — a false localizing sign worth knowing so it doesn't mislead lateralization)
• Central (transtentorial) herniation: diffuse downward pressure -> progressive rostral-caudal deterioration — declining consciousness, small-then-fixed pupils, decorticate then decerebrate posturing, ultimately brainstem failure
• Tonsillar herniation: cerebellar tonsils through the foramen magnum -> compresses the medulla -> respiratory and cardiovascular collapse, often with relatively preserved consciousness until late (a dangerous trap — posterior fossa lesions can deteriorate suddenly and catastrophically with limited warning)
• Subfalcine herniation: cingulate gyrus under the falx cerebri -> often relatively asymptomatic early, but can compress the anterior cerebral artery -> leg-predominant weakness; frequently a precursor/marker of more dangerous herniation evolving

4. Immediate Stabilization (ABCDE)

Airway/Breathing: secure per standard indications for declining GCS; ICP-minimizing induction technique if intubation needed (lidocaine pretreatment, etomidate preference — see Raised ICP protocol Section 3).

Circulation/Disability — the tumor-specific intervention:

• Dexamethasone is the first-line, disease-specific intervention for tumor-associated vasogenic edema — reduces peritumoral edema and can produce dramatic clinical improvement within hours, distinct from the general osmotherapy/hyperventilation/barbiturate algorithm used for other ICP-elevation causes
• Typical regimen (extrapolated from the closely related MSCC dosing evidence, individualize to clinical severity): initial IV bolus, then divided maintenance dosing, tapered over days-to-weeks once definitive therapy (surgery/radiotherapy) is underway or edema is controlled — use proton pump inhibitor or H2 blocker prophylaxis alongside high-dose corticosteroids
• For ACUTE herniation/impending herniation: proceed immediately to the full Raised ICP tiered algorithm (osmotherapy with mannitol/hypertonic saline, brief hyperventilation as a bridge only, emergent neurosurgical decompression) — dexamethasone's onset (hours) is too slow to be the sole response to an acutely herniating patient

Checklist:

5. Seizures

Tumor-associated seizures are common, particularly with cortical/supratentorial lesions. Seizure PROPHYLAXIS in patients WITHOUT a seizure history is generally NOT recommended by most contemporary neuro-oncology guidance (mirroring the no-prophylaxis principle established in the Stroke and ICH protocols in this system) — treat seizures if/when they occur (see Status Epilepticus protocol), rather than prophylactically loading all brain tumor patients with anticonvulsants.

6. Investigations

MRI brain with contrast is the imaging modality of choice for tumor characterization, edema extent, and herniation risk assessment (superior soft-tissue/edema detail vs CT); non-contrast CT remains the fastest option for acute deterioration/suspected hemorrhage into a tumor. Biopsy/histologic diagnosis should be obtained before committing to disease-specific chemotherapy, though this should not delay emergency stabilization (steroids, osmotherapy, surgical decompression) if the patient is acutely deteriorating.

7. Obstructive Hydrocephalus

Posterior fossa and intraventricular tumors can obstruct CSF flow -> acute hydrocephalus -> requires urgent ventriculostomy (EVD) for CSF diversion, analogous to the hydrocephalus management already established for ICH/SAH in this system — recognize this specific mechanism in tumors located near the ventricular system/aqueduct/4th ventricle.

8. Malignant Spinal Cord Compression (MSCC) — The Closely Related Neuro-Oncologic Emergency

Most commonly from metastatic lung, breast, and prostate cancer; also non-Hodgkin lymphoma, multiple myeloma, rectal cancer, sarcoma. May be the PRESENTING feature of previously undiagnosed malignancy in ~20% of cases.

Presentation: pain is the most common symptom (~90%), often preceding neurologic deficit by weeks — localized or radicular, worse with movement/coughing/sneezing/lying flat; distribution suggests level (mid-scapular = cervical, band-like chest/abdominal = thoracic, hip/lumbosacral = lumbosacral). Paresthesias/sensory deficits in ~70% (often unrecognized by patients). Motor deficits highly variable. Bowel/bladder dysfunction tends to occur LATE and portends a WORSE outcome — do not wait for autonomic involvement to escalate suspicion; assess post-void residual and rectal tone proactively in any cancer patient with new back pain.

MSCC occurs more often in the THORACIC spine than lumbosacral or cervical.

"Any patient with cancer presenting with new pain, sensory deficit, weakness, or bowel/bladder dysfunction should raise significant MSCC concern" — low threshold for imaging.

Imaging: MRI of the ENTIRE spine is the gold standard — 1 in 4 patients has noncontiguous levels of compression, and symptom location poorly predicts lesion level, so imaging only the symptomatic region risks missing a second lesion. CT myelography only if MRI contraindicated (lower diagnostic accuracy).

Treatment sequence:

1. Prompt empiric dexamethasone if MSCC suspected — typical regimen 10-16mg IV/PO initial bolus, then 4mg IV/PO every 4-6 hours, ideally within 12h of symptom onset; provides analgesia and may preserve neurologic function by reducing cord edema; can also reduce tumor burden in steroid-sensitive malignancies (e.g., lymphoma); give BEFORE radiotherapy; continue through acute treatment then taper over ~10-12 days once definitive therapy underway
2. Urgent multidisciplinary evaluation: radiation oncology, spine surgery, medical oncology — all patients should be seen by all three
3. Surgical decompression indicated for: significant cord compression, medically intractable pain, radioresistant tumors, spinal instability, progression of symptoms despite radiotherapy, or need for tissue diagnosis — favor aggressive surgery + postop radiotherapy in patients with favorable prognosis/higher neurologic recovery potential
4. Radiotherapy recommended for tumors with known radiosensitivity, patients unable to tolerate surgery, shorter life expectancy, diffuse spinal disease, or symptoms >48 hours — sarcomas and other radioresistant tumors may not benefit
5. Extremely acute pain + neurologic deficit may indicate vertebral burst fracture — requires urgent surgical intervention, distinct from the more gradual epidural-mass-driven MSCC presentation

Prognosis is poor: survival after MSCC diagnosis is typically 3-6 months; inpatient mortality 7.7-11.5% — underscoring both the urgency of treatment (neurologic function at diagnosis strongly predicts functional outcome) and the importance of realistic prognostic conversations.

9. Immunotherapy-Associated Neurotoxicity (ICANS) — Brief Cross-Reference

In CAR-T cell therapy patients, Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS) presents with encephalopathy, seizures, and variable motor findings, graded using the ICE (immune effector cell-associated encephalopathy) assessment tool. Usually reversible but can take days to weeks to resolve. Pathophysiology involves blood-brain barrier endothelial dysfunction and CAR-T cell trafficking into the CNS. Most patients are placed on prophylactic antiepileptics (a notable exception to the general "no seizure prophylaxis" principle elsewhere in this system, reflecting ICANS's specific, well-documented seizure risk). Management: monitor for/treat seizures and cerebral edema; high-dose corticosteroids to reverse symptoms; anakinra increasingly used at many centers; tocilizumab is indicated for concurrent cytokine release syndrome but NOT for ICANS alone — an important distinction, since tocilizumab does not cross the blood-brain barrier effectively and won't address isolated neurotoxicity. Close collaboration with the treating oncology/cellular therapy team is essential given the specialized nature of this complication.

10. Organ Support

Dexamethasone for tumor-associated edema; full Raised ICP tiered algorithm for acute herniation; ventriculostomy for obstructive hydrocephalus; standard ICU supportive care; seizure management if occurring (not prophylactic, except ICANS).

11. Consultation Matrix

12. Monitoring Framework

Frequent neuro checks with explicit herniation-sign screening (Section 3), serial imaging for edema/mass effect trend, steroid-related complication monitoring (hyperglycemia, GI bleeding risk, infection, myopathy with prolonged use), ICP monitoring if placed per Raised ICP protocol criteria.

13. Complications

Acute herniation/death, obstructive hydrocephalus, tumor hemorrhage, seizures, steroid-related complications (hyperglycemia, GI bleeding, myopathy, psychiatric effects, immunosuppression/infection risk with prolonged use), MSCC-related permanent paralysis/autonomic dysfunction if treatment delayed, ICANS-related prolonged encephalopathy. Prevention: prompt dexamethasone for known edema, early herniation recognition, GI prophylaxis with steroids, MRI whole-spine imaging to avoid missing noncontiguous MSCC lesions, prophylactic antiepileptics for ICANS specifically. Rescue: emergent osmotherapy/decompression for herniation, EVD for hydrocephalus, surgical decompression for MSCC.

14. Escalation & De-escalation

Escalate: any herniation sign -> immediate Raised ICP tiered algorithm + emergent neurosurgery; new/worsening MSCC-suspicious symptoms -> urgent whole-spine MRI + empiric dexamethasone.

De-escalate: edema/mass effect controlled, definitive therapy (surgery/RT/chemo) underway -> taper dexamethasone per the ~10-12 day taper principle (MSCC) or individualized schedule (brain tumor edema), wean ICP-directed therapy per Raised ICP protocol criteria.

15. ICU Discharge Criteria

Neurologically stable or improving, herniation risk resolved/mitigated (surgical decompression completed or edema controlled), steroid taper plan established, definitive oncologic treatment plan (surgery/RT/chemo) in place with appropriate specialty follow-up, MSCC patients have documented neurologic status at treatment initiation for prognostic tracking.

16. Documentation & Medicolegal Checklist

17. Key Guidelines

Lawton AJ, Lee KA, Cheville AL, et al. Assessment and management of patients with metastatic spinal cord compression: a multidisciplinary review. J Clin Oncol. 2019;37(1):61-71. Lee DW, Gardner R, Porter DL, et al. Current concepts in the diagnosis and management of cytokine release syndrome. Blood. 2014;124(2):188-195 (ICANS/CRS grading framework reference).

18. Landmark Evidence

Patchell RA, Tibbs PA, Regine WF, et al. Direct decompressive surgical resection in the treatment of spinal cord compression caused by metastatic cancer: a randomised trial. Lancet. 2005;366(9486):643-648 — established surgery + radiotherapy as superior to radiotherapy alone for ambulation preservation in appropriate MSCC candidates, foundational to current surgical decompression indications.

19. Controversies

Optimal dexamethasone dosing for tumor-associated vasogenic edema (as opposed to the better-defined MSCC regimen) lacks a single standardized protocol — dosing is often individualized to edema severity and clinical response rather than a fixed weight-based regimen. Seizure prophylaxis practice in brain tumor patients without a seizure history remains debated in some centers despite guideline movement away from routine use. ICANS management (anakinra vs corticosteroids as first-line, and their sequencing) is an actively evolving area given the relative novelty of CAR-T therapy and accumulating real-world experience.

20. References

1. Onco-emergencies (Malignant Spinal Cord Compression, SVC Syndrome) chapter. ICU Protocols: A Step-wise Approach, 2nd ed. Springer; 2020 (Ch. 9).
2. Neuro-Oncologic Emergencies / ICANS chapter. Washington Manual of Critical Care, 4th ed, 2025 (Ch. 33 region).
3. Lawton AJ, Lee KA, Cheville AL, et al. Assessment and management of patients with metastatic spinal cord compression. J Clin Oncol. 2019;37(1):61-71.
4. Patchell RA, Tibbs PA, Regine WF, et al. Direct decompressive surgical resection for MSCC. Lancet. 2005;366(9486):643-648.
5. Lee DW, Gardner R, Porter DL, et al. Current concepts in the diagnosis and management of cytokine release syndrome. Blood. 2014;124(2):188-195.
6. Mak KS, Lee LK, Mak RH, et al. Incidence and treatment patterns in hospitalizations for MSCC in the United States, 1998-2006. Int J Radiat Oncol Biol Phys. 2011;80(3):824-831.

See also: Raised ICP (Neurology System) for the full tiered ICP management algorithm applicable to acute herniation; Status Epilepticus (Neurology System) for seizure management if occurring.