Neurology Today-NeuroBowl Case Challenge
Diabetes Mellitus, Generalized Weakness, Swallowing Difficulties
It has been several months since we introduced the last Neurology Today-NeuroBowl Case Challenge, and with this issue we get back to the business of solving a case. To recap the last case presented (http://bit.ly/NT-casechallenge), we saw a 53-year-old man with a long-term history of smoking, hypertension, and type 1 diabetes mellitus that required insulin. He presented with generalized weakness for 24 hours and was unable to stand. He also had nausea and vomiting. Over the course of the next day, the weakness failed to resolve and he had shortness of breath and swallowing difficulties.
His computed tomography head scan and labs were unremarkable, as was his lumbar puncture. He reported that he been bitten by a tick recently, but the serology was unremarkable. He denied any recent respiratory or gastrointestinal infections.
On physical exam, his speech was hypophonic without aphasia, and cranial nerves were unremarkable. His strength was 1/5 throughout all extremieties, reflexes were brisk throughout, and his toes were upgoing bilaterally. His sensation to light touch and pinprick were decreased below the jaw line, but his pain and temperature were intact.
Based on the presentation, we asked: Where would you localize the lesion? What would you do next to make and confirm the diagnosis?
The patient had rapidly progressive paralysis of the limbs — not in an ascending fashion, just sudden weakness in the limbs. However, with hyper-reflexive and upgoing toes, an upper motor neuron pathology was more likely than a lower motor neuron pathology. Guillain-Barré syndrome (GBS) was less likely as his reflexes were preserved, and cerebrospinal fluid findings were not consistent with it either. Also, sensory findings — decreased light touch and pinpick, preserved pain and temperature — along with nausea/vomiting and swallowing/speech/breathing difficulties were suggestive of a lower brainstem lesion rather than an upper cervical spine lesion.
Some of our readers responded that the case indicated an upper cervical spine lesion — suggesting an infarction, myelitis, syringomyelia, or a mass — which would have been good localization, but symptoms of hypophonia, nausea/vomiting, respiratory difficulties, and preserved pain and temperature would suggest a lesion localized to the lower medial medulla. Given the patient's risk factors and the negative workup in the case, the patient was more likely to have a vascular lesion.
The patient did indicate that he had had a tick bite, so we did consider tick-related paralysis, but the serology was negative for that. We also considered that he might have been exposed to a toxin, but it wouldn't spare pain and temperature sensory modalities and upper cranial nerves. GBS was also considered, but the patient had preserved reflexes so an alternative diagnosis was more likely.
To solve the case, we did magnetic resonance imaging (MRI) of the brain, which indicated the following: The DWI sequence (photo A) showed a hyperintense heart-shaped lesion below the medial medulla in the distribution of the paramedian branches of the vertebral and anterior spinal arteries. And ADC sequences (photo B) showed a hypointense lesion corresponding to a DWI lesion, confirming our suspicion of diffusion restriction.
The patient's diagnosis was bilateral medial medullary syndrome. What caused this? The MR images showed only a hypoplasitic left vertebral, and there was no evidence of any thrombosis —the flow through basilar was intact — to suggest it as a cause of infarct. The most likely etiology is atherosclerotic disease, given his risk factors of hypertension, smoking history, and diabetes.
Dr. Patel is a neurology resident at the Medical College of Georgia.