Evaluation for Dizziness with Burning Sensations in Arms and Legs
Your patient likely has a small fiber sensory polyneuropathy with autonomic involvement, and you should prioritize evaluation for distal symmetric polyneuropathy (DSP) with electrodiagnostic studies, autonomic testing, and assessment for underlying causes like diabetes, while simultaneously ruling out central causes of dizziness if neurologic deficits are present.
Algorithmic Approach to Evaluation
Step 1: Characterize the Burning Sensation Component
The burning sensation predominantly in the arms and legs suggests small fiber sensory polyneuropathy (SFSN), which typically manifests as burning pain with possible allodynia. Autonomic and somatic C fibers are usually affected concurrently in this condition 1.
Key diagnostic criteria for DSP include:
- Neuropathic symptoms (burning, pain)
- Decreased or absent ankle reflexes
- Decreased distal sensation
- Abnormal nerve conduction studies
- Signs of autonomic involvement (sweating abnormalities, circulatory instability in feet) 1
Step 2: Characterize the Dizziness Component
Determine the timing and triggers of dizziness rather than trying to classify quality (vertigo vs. lightheadedness), as patients describe symptoms inconsistently 2.
Critical questions:
- Is dizziness triggered by head motion? (suggests benign paroxysmal positional vertigo)
- Associated with hearing loss/tinnitus? (suggests Menière disease)
- Triggered by standing or exertion? (suggests autonomic dysfunction or vertebrobasilar insufficiency)
- Constant vs. episodic?
Step 3: Rule Out Dangerous Central Causes
Perform focused neurologic examination:
- Look for brainstem neurologic deficits (suggests vertebrobasilar insufficiency or stroke) 3
- Assess for nystagmus and perform HINTS examination if acute vestibular syndrome present 4, 5
- Check for cerebellar ataxia signs 3
Important caveat: The positivity rate of head CT in emergency department patients with dizziness is only ~2%, but increases to 12% on MRI when neurologic findings are present 3. Don't over-image, but don't miss central causes.
Step 4: Evaluate for Autonomic Dysfunction
Given the combination of burning sensations (small fiber involvement) and dizziness, autonomic testing is warranted 1.
Recommended autonomic tests:
- Heart rate variability testing - detects diabetic polyneuropathy with nearly the same sensitivity as nerve conduction studies, with 97.5% specificity for parasympathetic deficits 1
- Orthostatic vital signs - check for orthostatic hypotension (drop of ≥20 mmHg systolic or ≥10 mmHg diastolic within 3 minutes of standing) 6
- Tilt table testing if orthostatic symptoms persist without documented hypotension 6, 7
Critical point: Chronic orthostatic intolerance, even without objective orthostatic hypotension, should prompt evaluation for autonomic and neurodegenerative disorders 6.
Step 5: Perform Electrodiagnostic Studies
Nerve conduction studies are essential to confirm DSP and assess large fiber involvement 1. This complements the clinical picture of small fiber neuropathy suggested by burning sensations.
Step 6: Screen for Underlying Causes
Essential laboratory evaluation:
- Fasting glucose and HbA1c (diabetes is the most common cause)
- Vitamin B12 and thiamine levels
- Thyroid function
- Complete metabolic panel (electrolytes, renal function)
- Consider checking for amyloidosis or autoimmune causes if initial workup negative 1
Step 7: Consider Special Circumstances
If dizziness is exertional: Evaluate for autonomic dysregulation 7 or, particularly in elderly patients with arm exertion triggers, consider subclavian steal syndrome with vertebrobasilar insufficiency 8. Duplex ultrasonography can identify retrograde vertebral artery flow 8.
If hyperventilation provokes symptoms: This may indicate autonomic dysregulation, even without spontaneous hyperventilation complaints 7.
Common Pitfalls to Avoid
- Don't dismiss chronic orthostatic symptoms without objective hypotension - this may represent early autonomic failure or prodromal neurodegenerative disease 6
- Don't order imaging reflexively - focus on clinical examination and targeted testing based on presence/absence of neurologic deficits 3
- Don't overlook medication side effects as a cause of both dizziness and autonomic symptoms 5
- Don't forget that physiological stressors (hypotension, fever, anemia) can unmask previously compensated vestibular impairments 5
Treatment Considerations
Treatment depends on the underlying cause identified through this evaluation. For autonomic dysregulation, medications targeting autonomic function have shown substantial improvement in 7 of 9 patients in one series 7. For DSP, addressing the underlying cause (e.g., glycemic control in diabetes) is paramount 1.