What is the appropriate workup for a 19-year-old male with anxiety and left-sided paresthesias?

Workup for a 19-Year-Old Male with Anxiety and Left-Sided Paresthesias

Immediate Assessment Priority

Rule out hyperventilation-induced paresthesias first, as anxiety-driven hyperventilation causes hypocapnia and hypocalcemia leading to peripheral nerve hyperexcitability and paresthesias—this is the most common benign cause in anxious young patients. 1

Essential Initial Workup

Electrolyte Panel (Critical First Step)

• Check serum calcium, magnesium, and potassium immediately to exclude metabolic causes of paresthesias, as hypomagnesemia, hypocalcemia, and hypokalemia can present with anxiety, hyperventilation, and perioral/extremity paresthesias 2
• These electrolyte derangements can both cause and mimic anxiety symptoms, creating a vicious cycle 2

Neurological Examination

• Assess for focal neurological deficits including motor weakness, sensory distribution patterns, reflexes, and coordination to distinguish between central versus peripheral nervous system pathology 3
• Determine if paresthesias follow a dermatomal or peripheral nerve distribution versus non-anatomical patterns suggestive of functional neurological disorder 4, 3
• Left-sided paresthesias in isolation without other focal findings in a young patient with prominent anxiety strongly suggests functional etiology or hyperventilation syndrome 1

Hyperventilation Provocation Test

• Observe respiratory pattern during anxiety episodes—rapid, shallow breathing with perioral and acral paresthesias developing within minutes confirms hyperventilation syndrome 1
• Voluntary hyperventilation reproduces symptoms when alveolar PCO2 declines by approximately 20 mmHg, causing increased axonal excitability before clinical symptoms appear 1

Secondary Considerations (If Initial Workup Normal)

Medication Review

• Document all current medications and supplements, as venlafaxine (an SNRI sometimes used for anxiety) can cause dose-related paresthesias, particularly at doses ≥150 mg/day 5
• SSRIs themselves rarely cause paresthesias but can be associated with psychogenic oral/lingual paresthesias in depression 6

Functional Neurological Disorder Assessment

• Evaluate for functional sensory symptoms if paresthesias are persistent, non-anatomical, and associated with other functional symptoms like dissociative episodes, functional weakness, or hypersensitivity 4
• Many patients with functional neurological disorder report hypersensitivity to touch, light, sound, and movement, which can become maintaining factors 4

Red Flags Requiring Urgent Neuroimaging

Obtain brain MRI urgently if any of the following are present:

• Sudden onset with severe headache
• Progressive weakness or sensory loss
• Cranial nerve abnormalities
• Altered mental status beyond anxiety
• Focal neurological signs on examination 3

These would suggest central nervous system pathology such as stroke, structural lesions, or demyelinating disease 3

Most Likely Diagnosis and Management

In a 19-year-old with isolated anxiety and left-sided paresthesias with normal electrolytes and neurological examination, this represents hyperventilation syndrome or functional sensory symptoms secondary to anxiety. 1, 4

Treatment Algorithm

1. Initiate SSRI therapy with sertraline 25-50 mg daily or escitalopram 5-10 mg daily as first-line pharmacological treatment for generalized anxiety disorder 7
2. Refer for individual cognitive behavioral therapy (CBT) targeting anxiety and breathing retraining, as combination treatment provides superior outcomes compared to medication alone 7
3. Teach diaphragmatic breathing and sensory grounding techniques to prevent hyperventilation episodes and manage acute anxiety 4
4. Educate about the physiological connection between anxiety, hyperventilation, and paresthesias to normalize symptoms and reduce catastrophic thinking 4

Expected Timeline

• SSRI response follows a logarithmic pattern with statistically significant improvement by week 2, clinically significant improvement by week 6, and maximal benefit by week 12 7
• Most adverse effects emerge within the first few weeks and typically resolve with continued treatment 7

Critical Pitfalls to Avoid

• Do not order extensive neurological workup (EMG, nerve conduction studies, brain MRI) in young patients with isolated anxiety and non-anatomical paresthesias without focal neurological findings—this reinforces illness behavior and increases healthcare costs unnecessarily 3
• Do not prescribe benzodiazepines for chronic anxiety management due to risks of dependence, tolerance, and withdrawal 7
• Do not dismiss symptoms as "just anxiety" without checking electrolytes first, as metabolic derangements require specific correction 2
• Avoid splinting or adaptive aids for functional sensory symptoms, as these increase attention to the affected area and can worsen symptoms 4