What are the potential causes and treatments for numbness and tingling on the left face with loss of left eye adduction?

Acute Stroke with Cranial Nerve Involvement

This presentation of left facial numbness and tingling combined with loss of left eye adduction (inability to move the left eye inward) represents a brainstem stroke affecting the left pons until proven otherwise and requires immediate emergency department evaluation with urgent neuroimaging. 1, 2

Immediate Emergency Actions Required

• Activate emergency medical services immediately for transport to a designated stroke center with advanced imaging and thrombolytic therapy capabilities 2
• The combination of facial sensory symptoms with cranial nerve deficits carries a 72% probability of stroke when accompanied by other neurological findings 1, 3
• Patients presenting with unilateral numbness have a 10% risk of completed stroke within the first week, with highest risk in the first 48 hours 1, 3

Most Likely Diagnosis: Pontine Stroke

The specific combination of left facial numbness/tingling (trigeminal nerve involvement) with loss of left eye adduction (cranial nerve VI palsy affecting the lateral rectus muscle) localizes to the left pons where these structures are anatomically adjacent 4, 5, 6. This represents ischemia or infarction in the vertebrobasilar system 4.

Key Anatomical Localization:

• Loss of adduction indicates left abducens nerve (CN VI) dysfunction, which courses through the pons 4
• Left facial numbness indicates involvement of the trigeminal sensory pathways at the pontine level 4, 5
• This constellation of findings is characteristic of medial medullary or pontine syndrome 6

Critical Emergency Department Evaluation

Immediate Neuroimaging (Within Minutes):

• Brain MRI with diffusion-weighted imaging is the preferred initial imaging to detect acute ischemic changes and must be performed immediately 1, 3, 2
• MRI differentiates ischemic from hemorrhagic stroke, which fundamentally changes treatment 1, 3
• If MRI unavailable, perform CT head without contrast to rule out hemorrhage 1, 3
• CT angiography or MR angiography from aortic arch to vertex to evaluate vertebrobasilar circulation 3, 2

Additional Urgent Assessment:

• Check bilateral radial pulses and blood pressure in both arms to differentiate stroke from acute arterial occlusion 1
• Perform Cincinnati Prehospital Stroke Scale assessment (facial droop, arm drift, abnormal speech) 1, 2
• ECG immediately upon arrival 2
• Assess for additional posterior circulation symptoms: ataxia, cranial nerve deficits, visual field loss, dizziness, imbalance, incoordination 4

Alternative Diagnoses to Exclude

While brainstem stroke is most likely, the following must be excluded through imaging and clinical assessment:

Structural Lesions:

• Tumors (meningioma, schwannoma, metastatic lesions) can cause progressive cranial nerve deficits 4
• Pontine gliomas or other brainstem masses 7
• These typically present more gradually than stroke but require urgent imaging 4

Inflammatory/Demyelinating Disease:

• Multiple sclerosis can present with isolated cranial nerve symptoms including facial numbness and eye movement abnormalities 5
• MRI would show multiple periventricular T2-hyperintense white matter lesions 5
• Cerebrospinal fluid analysis revealing oligoclonal IgG bands supports this diagnosis 5
• However, the acute presentation favors vascular etiology over demyelination 5

Peripheral Nerve Pathology:

• Bell's palsy causes facial weakness but is peripheral (affects entire ipsilateral face including forehead) and does not cause eye movement abnormalities or isolated sensory symptoms 4, 8
• Bell's palsy is rapid onset (<72 hours), unilateral facial nerve paresis/paralysis without identifiable cause 4
• The presence of eye adduction loss excludes isolated Bell's palsy 4, 8

Infiltrative Malignancy:

• Perineural spread of squamous cell carcinoma or other malignancies can affect multiple cranial nerves 9
• The "numb cheek-limp lower lid" syndrome involves infraorbital nerve and facial nerve branches from neoplastic infiltration 9
• This presents more gradually with progressive symptoms rather than acute onset 9

Treatment Based on Confirmed Diagnosis

If Ischemic Stroke Confirmed:

Acute Phase (Within 4.5 Hours):

• Intravenous tissue plasminogen activator (tPA) at 0.9 mg/kg (10% bolus over 1 minute, remainder over 59 minutes) if presenting within 4.5 hours and no contraindications 4
• Mechanical thrombectomy consideration for large vessel occlusion 1

Subacute Management:

• Dual antiplatelet therapy (aspirin + clopidogrel 75 mg) for the first 21 days in patients with symptomatic vertebrobasilar stenosis not undergoing revascularization, followed by long-term single antiplatelet therapy 1, 3
• Vascular imaging to identify vertebrobasilar stenosis requiring intervention 3

Eye Protection and Diplopia Management:

• If eye closure is impaired due to associated facial weakness, implement eye protection immediately to prevent corneal exposure 4
• For diplopia from eye movement limitation, consider occlusion (eye patch or occlusive contact lens) during acute phase 4
• Prisms (press-on or ground-in) may help following partial recovery 4
• Surgical management of persistent strabismus from third or sixth nerve palsy is complex and should be deferred until neurological recovery plateaus (typically 3-6 months) 4

Critical Pitfalls to Avoid

• Do not dismiss this as Bell's palsy based solely on facial symptoms—the presence of eye movement abnormality indicates central (brainstem) pathology, not peripheral facial nerve dysfunction 4, 8
• Do not delay imaging to obtain outpatient evaluation or institute other treatments—immediate triage to emergency department is mandatory 4
• Do not rely on normal CT without contrast to exclude stroke—MRI with diffusion-weighted imaging is far more sensitive for acute ischemic changes, particularly in the posterior fossa 1, 3
• Do not discharge patients with fluctuating or crescendo neurological symptoms under any circumstances 2

Follow-Up Requirements

• Reassess or refer to stroke specialist if new or worsening neurological findings develop at any point 4
• Reassess if ocular symptoms develop or worsen 4
• If incomplete neurological recovery at 3 months, refer to appropriate subspecialist (neurology, neuro-ophthalmology) 4