What is the diagnosis and recommended treatment for a patient with numbness in the left arm radiating to the left knee, accompanied by headaches and nausea/vomiting, who has tried over-the-counter (OTC) medications without relief?

Urgent Neurological Evaluation Required for Suspected Brain Metastases or Intracranial Pathology

This patient requires immediate neurological imaging (MRI brain with contrast) and urgent neurology consultation, as the combination of progressive numbness in non-contiguous body regions (left arm and left knee), headaches, and nausea/vomiting strongly suggests intracranial pathology such as brain metastases, primary brain tumor, or other space-occupying lesion rather than a primary headache disorder.

Critical Red Flags Present

This presentation contains multiple alarm features that mandate urgent evaluation rather than empiric headache treatment:

• Non-anatomical distribution of numbness: Numbness affecting both the left arm and left knee cannot be explained by a single peripheral nerve, nerve root, or spinal cord lesion, suggesting either multiple lesions or cortical/subcortical pathology 1

• Progressive neurological symptoms: The radiation of numbness from arm to knee over weeks indicates evolving pathology rather than a stable condition 2

• Headache with neurological deficits: New headache accompanied by focal neurological symptoms (numbness) is a red flag for secondary headache requiring immediate investigation 1, 2

• Persistent nausea and vomiting: When combined with headache and neurological symptoms, this triad suggests increased intracranial pressure from mass effect 1

Differential Diagnosis Priority

The most concerning diagnoses to rule out immediately include:

• Brain metastases: The combination of headache, nausea/vomiting, and progressive focal neurological deficits is classic for metastatic disease, which accounts for approximately 50% of all brain metastases from lung cancer 1

• Primary brain tumor: Presents similarly with progressive symptoms and focal deficits 1

• Cerebral venous thrombosis: Can cause headache, nausea, and focal neurological deficits, though typically presents more acutely 1

• Subdural hematoma: Particularly if there is any history of trauma or anticoagulation 1

Immediate Diagnostic Workup

Do not treat this as a primary headache disorder until life-threatening causes are excluded:

• MRI brain with and without gadolinium contrast is the gold standard for detecting brain metastases, primary tumors, and other intracranial pathology 1

• CT head without contrast if MRI is not immediately available, though it is less sensitive for detecting small metastases 1

• MR or CT venography if cerebral venous thrombosis is suspected based on imaging findings 1

Management of Symptoms Pending Workup

While awaiting urgent imaging and neurology evaluation, symptomatic management may include:

For Nausea and Vomiting (Likely from Increased Intracranial Pressure)

• Dexamethasone 4-16 mg/day is the corticosteroid of choice for brain tumor-associated edema, as it has minimal mineralocorticoid activity and can improve neurologic function 1

• Metoclopramide 10 mg IV or PO can address nausea through central dopamine receptor antagonism 3, 4

• Prochlorperazine 10 mg IV or PO is an alternative antiemetic with comparable efficacy 3, 4

For Headache (If Treating Symptomatically)

• Avoid NSAIDs initially until intracranial hemorrhage is excluded, as they increase bleeding risk 4

• Acetaminophen 1000 mg is safer while awaiting imaging 4

• Do not use triptans as they are contraindicated in patients with potential structural brain lesions 3, 4

Critical Pitfalls to Avoid

• Do not diagnose this as migraine: While migraine can cause headache and nausea, the progressive numbness in non-contiguous body regions is not consistent with migraine aura, which typically involves contiguous areas and resolves within 60 minutes 1, 3

• Do not delay imaging for a trial of migraine medications: The presence of progressive focal neurological deficits mandates immediate structural imaging 2

• Do not attribute symptoms to chronic migraine: Chronic migraine is defined as 15+ headache days per month for 3+ months, and this patient describes recent onset over weeks 1

• Do not use corticosteroids without imaging if cerebral venous thrombosis is possible: While dexamethasone is appropriate for tumor-related edema, management of CVT requires anticoagulation even in the presence of hemorrhage 1

Disposition

This patient requires same-day neurological imaging and consultation. If brain metastases or other mass lesion is confirmed, management will depend on the number and location of lesions, primary cancer type (if known), and overall prognosis, potentially including surgical resection, stereotactic radiosurgery, whole-brain radiation therapy, or systemic therapy 1. The combination of corticosteroids with definitive treatment of the underlying lesion(s) provides the best outcomes for symptom control 1.