Disclosures: Arielle Berkowitz, DO: No financial relationships or conflicts of interest

Case Diagnosis: 21-year-old female with history of scoliosis and Chiari I malformation with basilar invagination status post surgical decompression.

Case Description: This patient with juvenile scoliosis and Chiari I malformation presented with one year of difficulty ambulating and progressive left sided weakness. On examination she was tachycardic, with neurological examination notable for 3-4/5 strength; brisk reflexes throughout with bilateral Hoffman/Babinski signs and bilateral sustained ankle clonus; and a wide-based gait. MRI brain/spine confirmed basilar invagination with compression of the cervicomedullary junction, mild hydrocephalus, and a 2 mm cervicothoracic syrinx. Patient underwent endoscopic endonasal odontoidectomy, occiput/C1/C2 posterior lateral fusion, suboccipital craniectomy, and C1 laminectomy.

Setting: Acute Inpatient RehabilitationAssessment/

Results: On postoperative day ten, the patient was transferred from acute care, after which she developed visual hallucinations, pseudobulbar affect, dysarthria/dysphagia, constipation, and hypoxia. Tachycardia persisted. Hypoxia was attributed to central sleep apnea, constipation to post-operative inactivity and opioids, dysarthria/dysphagia to postoperative edema, and pseudobulbar affect/hallucinations to medullary mechanical manipulation. After a negative chest radiograph, CT angiogram chest/abdomen, ultrasound duplex, and infectious/endocrine lab testing, tachycardia was attributed to unopposed sympathetic nervous system output.

Discussion: The nucleus tractus solitarius (NTS) of the medulla integrates afferent inputs from the aortic baroreceptor and carotid sinus arterial chemoreceptor and provides efferent output to the dorsal motor nucleus of the vagus (DMV) and nucleus ambiguus (NA), two parasympathetic nuclei crucial for reducing heart rate. The NA additionally innervates muscles required for speaking and swallowing. Loss of NTS output due to compression and/or mechanical manipulation may have resulted in disinhibited cardiac sympathetic tone, producing tachycardia, and in dysarthria/dysphagia via impaired NA output.

Conclusion: In cases of brainstem compression, it is important to consider the role of the autonomic nervous system. Tachycardia can result from parasympathetic compromise leading to unopposed sympathetic activity.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/unopposed-sympathetic-activity-in-the-setting-of-cervical-medullary-decompression-a-case-report/