A
52-year-old man presents to your clinic with a few months history of
intermittent paresthesias (tingling and numbness) and mild pain in the
bottom of his feet. Examination shows normal mental status, brisk
reflexes at the knees, but absent ankle jerks, upgoing toes and
hypoesthesia to pinprick in the bottom of his feet. Vibration sensation
is decreased in the toes.
You order blood work to evaluate for possible causes of peripheral neuropathy or polyneuropathy. Which abnormal finding is most likely?
a) Low TSH
b) High TSH
c) Low B12
d) High B6
e) High Glucose
ans: This patient has features suggesting a peripheral neuropathy (paresthesias or tingling and pain in the feet) PLUS a myelopathy (upgoing toes and brisk knee jerks), raising the possibility of subacute combined degeneration, a complication of severe vitamin B12 deficiency. Thyroid disease (hypo or hyperthyroidism), B6 intoxication, and hyperglycemia can all cause peripheral neuropathies but are unlikely to produce signs of a myelopathy, such as those described above. Other causes of subacute combined degeneration include neurosyphilis, tropical myeloneuropathies, Lyme disease, multiple sclerosis, HIV-1 associated vacuolar myelopathy, etc.
49-year-old, previously healthy woman presents to the emergency department because of difficulty walking and bilateral foot pain. This was preceded 2 weeks earlier by a gastrointestinal syndrome with 2 days of diarrhea. She states that she developed some weakness in her feet 4 days ago, but today she has barely been able to walk. She has also noticed decreased handgrip strength and mild dyspnea. In addition, she describes burning pain in her feet and lancinating lower back pain. She has no bowel or bladder symptoms. Your exam shows BP 198/105, pulse 110, respiratory rate 28/minute. O2 sat is 98% on room air. Her lungs are clear. She has a normal mental status, cranial nerve examination, and finger nose finger testing. She has no reflexes in any limb. Arm strength is good except for hand intrinsic muscles that are 4-/5. Leg muscle strength includes 3/5 weakness of foot dorsiflexion and plantar flexion and 4/5 hip flexion and knee extension. The sensory exam shows some decreased vibration sense and some pinprick hyperalgesia in the soles of her feet. She has difficulty walking and a bilateral steppage gait.
Which of the following tests would you do next?
ans:The presentation with a painful, symmetric, ascending (motor more than sensory) polyneuropathy, with no reflexes, is consistent with an acute inflammatory demyelinating polyneuropathy or Guillain-BarrĂ© syndrome (GBS). Lumbar puncture is important to rule out infectious and inflammatory causes of a polyradiculopathy. It may also show a “cytoalbuminolgic dissociation” (high protein, with no or few white blood cells; WBCs), characteristic of GBS – after the first week or so. MRI of the lumbosacral spine is worthwhile if an acute lumbosacral polyradiculopathy (cauda equina syndrome) is the initial diagnosis, but upper extremity involvement and respiratory problems make this unlikely. Anti-Hu antibodies are associated with paraneoplastic polyneuropathies (sensory ganglionopathy or sensorimotor polyneuropathy) that are unlikely to present acutely as in this case. Lyme serology is always worthwhile, but nothing in this case points to a history of a tick bite or other typical finding in that disease. B12 deficiency would not explain this clinical picture.
This patient has signs of respiratory distress, with a RR of 28/minute and symptoms of dyspnea. Weakness may be progressing to involve respiratory muscles (particularly the diaphragm), and respiratory failure could occur at any time, requiring intubation. When the FVC is less than 15 mL/kg and the NIF closer to zero (normal is at least −60 cm H2O) or less (negative) than −25 cm H2O, prophylactic intubation and ventilation should be considered. Also, a decrease of more than 30% of FVC or NIF in 24 hours may indicate the need for intubation. Nerve conduction studies and EMG can help in the diagnostic evaluation of GBS but are not a task to be done in the emergency department. Additionally, this patient is already presenting signs of autonomic instability (with hypertension and tachycardia) that could change to hypotension or bradycardia at any time. ICU admission is required.
he use of IVIG or plasmapheresis is the first line of therapy in patients with GBS with progressive weakness. IV steroids and oral prednisone are not beneficial and could be potentially harmful. Intubation is not indicated as the FVC and NIF remain stable. Observation alone is not appropriate in patients with significant weakness and respiratory or autonomic compromise.
You order blood work to evaluate for possible causes of peripheral neuropathy or polyneuropathy. Which abnormal finding is most likely?
a) Low TSH
b) High TSH
c) Low B12
d) High B6
e) High Glucose
ans: This patient has features suggesting a peripheral neuropathy (paresthesias or tingling and pain in the feet) PLUS a myelopathy (upgoing toes and brisk knee jerks), raising the possibility of subacute combined degeneration, a complication of severe vitamin B12 deficiency. Thyroid disease (hypo or hyperthyroidism), B6 intoxication, and hyperglycemia can all cause peripheral neuropathies but are unlikely to produce signs of a myelopathy, such as those described above. Other causes of subacute combined degeneration include neurosyphilis, tropical myeloneuropathies, Lyme disease, multiple sclerosis, HIV-1 associated vacuolar myelopathy, etc.
49-year-old, previously healthy woman presents to the emergency department because of difficulty walking and bilateral foot pain. This was preceded 2 weeks earlier by a gastrointestinal syndrome with 2 days of diarrhea. She states that she developed some weakness in her feet 4 days ago, but today she has barely been able to walk. She has also noticed decreased handgrip strength and mild dyspnea. In addition, she describes burning pain in her feet and lancinating lower back pain. She has no bowel or bladder symptoms. Your exam shows BP 198/105, pulse 110, respiratory rate 28/minute. O2 sat is 98% on room air. Her lungs are clear. She has a normal mental status, cranial nerve examination, and finger nose finger testing. She has no reflexes in any limb. Arm strength is good except for hand intrinsic muscles that are 4-/5. Leg muscle strength includes 3/5 weakness of foot dorsiflexion and plantar flexion and 4/5 hip flexion and knee extension. The sensory exam shows some decreased vibration sense and some pinprick hyperalgesia in the soles of her feet. She has difficulty walking and a bilateral steppage gait.
Which of the following tests would you do next?
- a) MRI of the lumbosacral spine
- b) Lumbar puncture
- c) Anti-Hu antibodies
- d) Lyme serology
- e) Vitamin B12 levels
ans:The presentation with a painful, symmetric, ascending (motor more than sensory) polyneuropathy, with no reflexes, is consistent with an acute inflammatory demyelinating polyneuropathy or Guillain-BarrĂ© syndrome (GBS). Lumbar puncture is important to rule out infectious and inflammatory causes of a polyradiculopathy. It may also show a “cytoalbuminolgic dissociation” (high protein, with no or few white blood cells; WBCs), characteristic of GBS – after the first week or so. MRI of the lumbosacral spine is worthwhile if an acute lumbosacral polyradiculopathy (cauda equina syndrome) is the initial diagnosis, but upper extremity involvement and respiratory problems make this unlikely. Anti-Hu antibodies are associated with paraneoplastic polyneuropathies (sensory ganglionopathy or sensorimotor polyneuropathy) that are unlikely to present acutely as in this case. Lyme serology is always worthwhile, but nothing in this case points to a history of a tick bite or other typical finding in that disease. B12 deficiency would not explain this clinical picture.
This patient has signs of respiratory distress, with a RR of 28/minute and symptoms of dyspnea. Weakness may be progressing to involve respiratory muscles (particularly the diaphragm), and respiratory failure could occur at any time, requiring intubation. When the FVC is less than 15 mL/kg and the NIF closer to zero (normal is at least −60 cm H2O) or less (negative) than −25 cm H2O, prophylactic intubation and ventilation should be considered. Also, a decrease of more than 30% of FVC or NIF in 24 hours may indicate the need for intubation. Nerve conduction studies and EMG can help in the diagnostic evaluation of GBS but are not a task to be done in the emergency department. Additionally, this patient is already presenting signs of autonomic instability (with hypertension and tachycardia) that could change to hypotension or bradycardia at any time. ICU admission is required.
he use of IVIG or plasmapheresis is the first line of therapy in patients with GBS with progressive weakness. IV steroids and oral prednisone are not beneficial and could be potentially harmful. Intubation is not indicated as the FVC and NIF remain stable. Observation alone is not appropriate in patients with significant weakness and respiratory or autonomic compromise.
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