Sniff test |
Required to confirm paralysis* |
May be difficult to diagnose bilateral paralysis |
Can demonstrate paresis, paralysis, or paradoxical movement |
Pulmonary spirometry |
Unilateral: Mild-to-moderate restrictive deficit, or sometimes normal in spite of symptoms |
Bilateral: Moderate-to-severe restrictive deficit |
Mixed deficit if comorbid conditions are present |
Electrodiagnostics |
Phrenic nerve conduction studies quantitate the neural and motor deficits and compare value obtained (right and left) to standard values |
Diaphragm electromyography to assess whether there is preservation of VMUs to determine feasibility of reinnervation |
Most important for surgical decision making |
Used to rule out polyneuropathy and systemic neurodegenerative conditions¶ |
Technically demanding; availability limited due to lack of skilled technicians with significant experience in phrenic nerve and diaphragm testing |
MR imaging cervical spine |
Obtain when there is suspected or known history of cervical spine diseaseΔ |
Findings useful to determine need for referral to spine surgeon |
Does not show peripheral cervical root or phrenic nerve compression |
CT neck and chest |
Obtain when there is suspected or known history of organic pathology in neck or chest, or prior surgical intervention |
Not necessary to confirm paralysis |
Polysomnography |
Used to confirm if there is sleep-disordered breathing◊ |
Assists in determining utility of BiPAP or CPAP |
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