What is the diagnosis and management for a 66kg, 158cm, adult patient with a 1-week history of left eye ptosis, watery nasal discharge, intermittent fever, frontal headache, and postprandial vomiting, with a past medical history (PMH) of no previous admissions or surgeries, no known drug allergies (FDA), and a family history of hypertension (HPN), currently presenting with hypotension, tachycardia, normal oxygen saturation, impaired vision in the left eye, left pupillary dilation, and nuchal rigidity, and being treated with Mannitol (mannitol) 100cc q6 hours, ceftriaxone (ceftriaxone) 2g per day, and Celecoxib (celecoxib) 100mg as needed?

Diagnosis: Third Nerve Palsy with Pupillary Involvement - Likely Posterior Communicating Artery Aneurysm or Infectious Meningitis

This patient requires immediate neuroimaging (MRI with gadolinium and MR angiography or CT angiography) to rule out a posterior communicating artery aneurysm, which is a neurosurgical emergency. 1, 2, 3 The combination of left eye ptosis, complete ophthalmoplegia with fixed dilated pupil (6mm, non-reactive), nuchal rigidity, fever, and progressive symptoms over 48 hours suggests either a compressive lesion (aneurysm) or infectious meningitis with cranial nerve involvement.

Critical Diagnostic Considerations

Third Nerve Palsy Classification

The patient presents with pupil-involving third nerve palsy, characterized by: 1, 2

• Complete ptosis of the left eye
• Dilated left pupil (6mm) with no reaction to light
• Marked limitation of adduction, elevation, and depression (preserved abduction indicates intact CN VI)
• Fixed eye position in primary gaze

The dilated pupil with ptosis mandates urgent evaluation for compressive lesions, particularly posterior communicating artery aneurysm, which is immediately life-threatening. 1, 3 The pupillary fibers run superficially on the third nerve and are preferentially affected by external compression. 1

Infectious Meningitis as Concurrent Diagnosis

The clinical picture strongly suggests bacterial meningitis with cranial nerve involvement: 4

• Fever (maximum 39°C) with frontal headache (8/10 severity)
• Nuchal rigidity on examination
• Progressive neurological deterioration (vomiting, cranial nerve palsy)
• Elevated WBC count (as reported from outside facility)
• Watery nasal discharge preceding neurological symptoms (possible sinusitis as source)

The combination of nuchal rigidity, fever, headache, and cranial nerve palsy represents a medical emergency requiring immediate empiric antimicrobial therapy while awaiting imaging and lumbar puncture. 4

Immediate Management Algorithm

Step 1: Stabilization and Urgent Imaging (Within 1 Hour)

Obtain MRI brain with gadolinium and MR angiography immediately. 3 If MRI is unavailable or delayed, proceed with non-contrast CT head followed by CT angiography to evaluate for: 3

• Subarachnoid hemorrhage (sensitivity 98%, specificity 99% for CT)
• Aneurysm (particularly posterior communicating artery)
• Intracranial mass or abscess
• Signs of meningitis (basilar enhancement, hydrocephalus)

Do not delay imaging for lumbar puncture - the presence of focal neurological deficits (third nerve palsy) and potential increased ICP (vomiting, progressive symptoms) makes LP potentially dangerous until mass lesion is excluded. 4

Step 2: Empiric Antimicrobial Therapy (Immediate)

Initiate broad-spectrum antibiotics immediately after blood cultures, do not wait for imaging or LP results. 4 The current regimen of ceftriaxone 2g/day is inadequate for bacterial meningitis:

Recommended regimen for bacterial meningitis with cranial nerve involvement:

• Ceftriaxone 2g IV every 12 hours (4g/day total) PLUS
• Vancomycin 15-20 mg/kg IV every 8-12 hours PLUS
• Dexamethasone 10mg IV every 6 hours (started before or with first antibiotic dose)

The dexamethasone should be given for 4 days to reduce neurological sequelae in bacterial meningitis. 4

Step 3: Intracranial Pressure Management

Continue mannitol 100cc (approximately 20g) every 6 hours as currently prescribed. 4, 5 Mannitol is effective in reducing pathological ICP, with reduction proportional to baseline ICP (0.64 mmHg decrease per 1 mmHg baseline elevation). 5 The current dosing (approximately 0.3g/kg every 6 hours for 66kg patient) is appropriate.

Monitor for signs of increased ICP: 4

• Worsening level of consciousness
• Pupillary changes in the right eye
• Development of posturing
• Worsening headache or vomiting

If ICP crisis develops (somnolence, posturing, bilateral pupillary changes), administer 100ml of 23.4% hypertonic saline IV immediately. 4

Step 4: Lumbar Puncture (After Imaging Clears Mass Lesion)

Once imaging excludes mass effect, hydrocephalus, or impending herniation, perform LP with: 4

• Opening pressure measurement
• Cell count with differential
• Glucose and protein
• Gram stain and bacterial culture
• Consider fungal studies given geographic location and diabetes risk factors

If imaging shows mass lesion or significant mass effect, LP is contraindicated. 4

Differential Diagnosis Priority

1. Posterior Communicating Artery Aneurysm (Most Urgent)

This is the diagnosis that cannot be missed - it is immediately life-threatening and requires neurosurgical intervention. 1, 3 The pupil-involving third nerve palsy is the classic presentation, though the concurrent fever and meningismus suggest a more complex picture (possible aneurysmal rupture with meningitis, or concurrent processes). 3

2. Bacterial Meningitis with Cranial Nerve Involvement

The prodrome of upper respiratory symptoms, fever, headache, nuchal rigidity, and elevated WBC strongly suggest bacterial meningitis. 4 Cranial nerve palsies occur in 10-20% of bacterial meningitis cases, with CN III, VI, and VII most commonly affected. 4

Possible sources include: 4

• Acute bacterial sinusitis (watery nasal discharge, frontal headache) with intracranial extension
• Community-acquired meningitis
• Sinogenic intracranial complications

3. Cavernous Sinus Thrombosis

The combination of ophthalmoplegia, pupillary involvement, and fever could represent cavernous sinus thrombosis secondary to sinusitis. 4 However, the absence of proptosis, periorbital edema, or bilateral involvement makes this less likely. 4

4. Mucormycosis (Critical in Diabetic Patients)

Given the geographic location, fever, sinusitis prodrome, and rapid progression, invasive fungal sinusitis (mucormycosis) must be considered, particularly if the patient has undiagnosed diabetes. 6 The hyperglycemia mentioned in family history (HPN) raises concern for undiagnosed diabetes mellitus.

Check blood glucose immediately and HbA1c. 6 If elevated, add amphotericin B 1mg/kg/day IV to the regimen and obtain urgent ENT consultation for endoscopic sinus evaluation and biopsy. 6

Critical Pitfalls to Avoid

Do not assume pupil-sparing third nerve palsy based on incomplete examination - this patient has complete pupillary involvement requiring urgent aneurysm workup. 1, 2

Do not delay antibiotics for imaging or LP - bacterial meningitis requires treatment within 1 hour of presentation to reduce mortality and morbidity. 4

Do not perform LP before imaging in a patient with focal neurological deficits - risk of herniation outweighs diagnostic benefit. 4

Do not miss mucormycosis in diabetic patients with sinusitis and cranial nerve palsies - this requires surgical debridement in addition to antifungals and has high mortality if delayed. 6

Do not discontinue mannitol abruptly - ICP management should be continued until definitive diagnosis and treatment are established. 4, 5

Additional Diagnostic Studies

• Blood cultures (before antibiotics) 4
• Complete blood count with differential 4
• Comprehensive metabolic panel (assess renal function for mannitol therapy, check glucose) 5
• Coagulation studies (before LP, assess for DIC in sepsis) 4
• Inflammatory markers (CRP, ESR) 4
• HbA1c (screen for diabetes given family history and mucormycosis risk) 6

Neurosurgical Consultation

Obtain immediate neurosurgical consultation regardless of imaging findings, given the pupil-involving third nerve palsy and potential need for: 3

• Aneurysm clipping or coiling if identified
• EVD placement if hydrocephalus develops
• Surgical decompression if abscess or mass identified
• Endoscopic sinus surgery if mucormycosis confirmed 6

Prognosis and Monitoring

The patient requires ICU-level monitoring with: 4

• Hourly neurological assessments (GCS, pupillary responses, motor function)
• Continuous cardiac monitoring
• Strict blood pressure control (avoid hypotension and extreme hypertension)
• Serum osmolality monitoring (target 300-320 mOsm/kg with mannitol therapy) 5
• Fluid balance monitoring

The combination of third nerve palsy with meningismus carries significant morbidity risk - permanent vision loss, chronic ophthalmoplegia, and cognitive deficits are possible even with appropriate treatment. 1, 7