What is the most likely cause and immediate management for an adult with a seizure disorder and brain tumor who presents with an acute dental infection, altered mental status, a low CIWA‑R score (2), a new seizure, and a lactate of 11.4 mmol/L?

Immediate Management of Seizure with Severe Lactic Acidosis in a Patient with Brain Tumor

This patient requires immediate stabilization for status epilepticus, urgent evaluation for sepsis and intracranial pathology, and aggressive treatment of the underlying metabolic crisis—the lactate of 11.4 mmol/L indicates life-threatening tissue hypoperfusion that demands immediate intervention.

Most Likely Cause

The constellation of findings points to sepsis from the acute dental infection as the primary driver, with the seizure likely representing:

• Septic encephalopathy with metabolic derangement causing breakthrough seizure in a patient with pre-existing seizure disorder and structural brain lesion 1
• Severe tissue hypoperfusion (lactate >4 mmol/L indicates profound hypoperfusion; 11.4 mmol/L suggests septic shock or inadequate resuscitation) 1
• The low CIWA score (2) effectively rules out alcohol withdrawal as the seizure etiology 2

Alternative considerations include:

• Brain tumor progression causing new seizure activity 1
• Nonconvulsive status epilepticus contributing to altered mental status 1
• CNS infection (brain abscess from dental source, meningitis) 1

Immediate Stabilization (First 15 Minutes)

Airway and Seizure Control

• Administer benzodiazepine immediately (lorazepam 4 mg IV at 2 mg/min) for ongoing or recurrent seizure activity 3
• Secure airway and prepare for intubation—respiratory depression is the most important risk with benzodiazepines, and this patient has multiple risk factors for airway compromise 3
• If seizures persist after 10-15 minutes, give second 4 mg dose of lorazepam 3
• Prepare second-line antiepileptic (phenytoin/fosphenytoin, valproate, or levetiracetam) if seizures continue 4

Hemodynamic Resuscitation

• Obtain blood cultures immediately, then start broad-spectrum antibiotics without delay—do not wait for imaging or lumbar puncture 4
• Initiate aggressive fluid resuscitation with crystalloid boluses (500-1000 mL over 15-30 minutes, repeated based on response) targeting lactate clearance and perfusion markers 1
• Monitor for fluid overload (increased JVP, crackles) given altered mental status and potential for cerebral edema from brain tumor 1

Diagnostic Workup (Concurrent with Stabilization)

Essential Laboratory Tests

• Bedside glucose immediately—hypoglycemia is a treatable cause of both seizures and altered mental status 5, 4
• Serum sodium—hyponatremia can precipitate seizures and is common in status epilepticus 5, 4
• Complete metabolic panel including calcium and magnesium—both can cause seizures, especially in patients with malignancy 5, 4
• Arterial blood gas—essential to assess metabolic acidosis severity and guide resuscitation 5
• Complete blood count—evaluate for infection, sepsis 5
• Procalcitonin—values ≥0.5 ng/mL suggest bacterial infection; >10 ng/mL indicates septic shock 4

Neuroimaging Strategy

Perform emergent non-contrast head CT before lumbar puncture to exclude:

• Mass effect or herniation risk (critical before LP in immunocompromised/altered patient) 1, 4
• Intracranial hemorrhage 1, 4
• Brain tumor progression 1
• New structural lesion or abscess from dental infection 1

High-risk features mandating emergent CT are present: altered mental status, known brain tumor, fever (likely from dental infection), and focal neurologic findings 4

Lumbar Puncture Decision

Perform LP after negative CT given:

• Altered mental status with fever in setting of potential odontogenic infection 4
• Need to exclude CNS infection (meningitis, brain abscess) 1, 4
• CSF should include cell count, glucose, protein, Gram stain, culture, and viral PCR panel 4

Electroencephalography

Obtain emergent EEG to rule out nonconvulsive status epilepticus—critical in any patient with persistent altered mental status after seizure 1, 4

Ongoing Management

Seizure Control

• Place patient on anticonvulsant secondary prophylaxis—the vast majority of brain tumor patients who experience seizure should receive this 1
• Levetiracetam is preferred in brain tumor patients because it:
  • Has no enzyme-inducing properties (avoids chemotherapy interactions) 1, 6
  • Demonstrates excellent efficacy (77% complete seizure control in metastatic brain tumors) 6
  • Is well-tolerated with minimal adverse effects 6
• Avoid valproic acid in women of childbearing age due to teratogenicity 1
• Avoid phenytoin, phenobarbital, and carbamazepine as first-line agents 1

Sepsis Management

• Continue fluid resuscitation targeting lactate clearance—repeat lactate every 2-4 hours 1
• Reduce fluid rate if signs of overload develop (increased JVP, pulmonary crackles) but continue if hypoperfusion persists 1
• Initiate vasopressors if hypotension persists after 2-4 L crystalloid 1
• Treat dental infection source—coordinate urgent dental/oral surgery consultation for definitive source control

Critical Care Monitoring

• Admit to ICU for continuous monitoring given septic shock, status epilepticus, and altered mental status 4
• Continuous EEG monitoring if mental status does not improve after seizure termination 1, 4
• Serial neurologic examinations to detect tumor progression or new deficits 1

Critical Pitfalls to Avoid

• Do not delay antibiotics while awaiting imaging or cultures—mortality increases dramatically with each hour of delay in septic patients 4
• Do not assume seizure is from alcohol withdrawal with CIWA score of 2—this effectively excludes withdrawal 2
• Do not overlook nonconvulsive status epilepticus—EEG is mandatory with persistent altered mental status 1
• Do not give excessive fluids without monitoring for cerebral edema—brain tumor patients are at risk for symptomatic edema 1
• Do not attribute everything to known brain tumor—new-onset or worsening seizures often indicate progression and require reimaging 1
• Do not miss CNS infection—dental infections can seed intracranially, and LP is indicated after CT 1, 4
• Do not use enzyme-inducing antiepileptics (phenytoin, carbamazepine, phenobarbital) in brain tumor patients who may need chemotherapy 1

Disposition

ICU admission is mandatory given:

• Septic shock (lactate 11.4 mmol/L) 1, 4
• Status epilepticus requiring benzodiazepines 3
• Altered mental status not returned to baseline 4
• Need for continuous monitoring and potential for respiratory depression from benzodiazepines 3