A 26-year-old woman with no past medical history presents to the emergency department with several days of fatigue, difficulty climbing stairs, and double vision. She has one-word dyspnea and appears to be retracting. Her chest x-ray is normal, as are all her initial laboratory studies. She mentions having had an upper respiratory infection 1 week before. She does not take any medications and has not traveled recently. Vital signs: heart rate, 105 bpm; sinus tachycardia; blood pressure, 145/90 mm Hg; respiration rate, 30 breaths per minute; temperature, 37.2°C. She is in moderate respiratory distress and is using accessory muscles of respiration. She has no rashes. She is drooling and has difficulty clearing her secretions. Her oropharynx is clear. Her neurological examination is notable for ptosis, bilateral 6th nerve palsy, bilateral facial weakness, and neck flexion, 3/5; deltoids, 3/5; biceps, 3/5; triceps, 3/5; wrist extensors and intrinsic hand muscles, 5/5; ileopsoas, 4+/5; quadriceps, 4+/5; hamstrings, 5/5; tibialis anterior, 5/5; and gastrocnemius, 5/5. Her sensory examination is normal, as are her reflexes.
What is the differential diagnosis for this patient?
Acute bilateral weakness can be due to either central or peripheral lesions. When approaching such a patient, it is advisable to develop a methodology beginning with brain and spinal cord etiologies and moving peripherally, ruling out possibilities based on examination, imaging, and laboratory findings. The acuity of the presentation and the symmetry and pattern of weakness can be helpful. Generalized fatigue due to cardiopulmonary disease, anemia, malignancy, depression, and fibromyalgia, for example, can overlay objective muscle weakness. Similarly, pain can limit the motor examination. A broad overview of possibilities using the mnemonic VINDICATE is shown in Table 6-1.
Table 6-1.Acute Motor and Sensory Weakness Differential Diagnosis |Favorite Table|Download (.pdf) Table 6-1. Acute Motor and Sensory Weakness Differential Diagnosis
| ||Pure Motor Findings ||Motor and Sensory |
|Vascular ||Bilateral motor strip, centrum semiovale, corona radiata, or internal capsule infarction, or hemorrhage; Azygous ACA with ACA stroke; Subdural hemorrhage; bilateral/central pontine infarctions, hemorrhage; MCA-ACA watershed infarction can cause “man-in-a-barrel” syndrome with proximal arm and proximal leg weakness ||Bilateral cortical or subcortical infarction, hemorrhage; bilateral brainstem infarctions, hemorrhage |
|Infection/Inflammation ||Bilateral motor strip, centrum semiovale, corona radiata, or internal capsule abscess, demyelinating disease; bilateral/central pontine abscess, demyelinating disease, basilar meningitis, sarcoid ||Bilateral cortical or subcortical; bilateral brainstem infarctions, abscess, demyelinating disease, basilar meningitis, sarcoid, rhombencephalitis |
|Neoplasm ||Paramedian/falcine tumor; Bilateral motor strip, centrum semiovale, corona radiata, internal capsule or pontine tumor, carcinomatous meningitis ||Bilateral cortical, bilateral subcortical infarction or brainstem tumor, carcinomatous meningitis |
|Drugs ||Accidental ingestion: Carbon monoxide poisoning (globus pallidus injury), Methanol poisoning (putaminal injury) || |
|Idiopathic, Iatrogenic ||Seizure with Todd’s paralysis ||Bickerstaff-Cloake |
|Congenital/Genetic ||Alternating hemiplegia of childhood; Migraine with hemiplegia; Progressive bulbar palsy ||Leukodystrophy |
|Autoimmune || ||Bilateral multiple sclerosis lesions, ADEM, acute hemorrhagic encephalomyelitis, tumefactive MS, vasculitis, Behcet’s syndrome |