The authors Sun-Uk Lee et al, identified 18 patients with dorsal medullary infarcts amongst 172 patients presenting with medullary infarction. Their results can be summarized as follows:
1) Lesions restricted to the dorsal portion of the medulla may present isolated acute vestibular syndrome.
· Vertigo or unsteadiness (n=15), and was associated with tinnitus the ipsilesional (n=2) or contralesional ear (n=1).
2) Almost all the patients with dorsal medullary infarctions show findings of central vestibulopathy according to the affected neural structures.
· Direction-changing Gaze Evoked Nystagmus (n=12)
· Negative Head Impuse Test (n=8)
· Skew deviation (n=7)
· Head Shaking Nystagmus in the opposite direction of Spontanous Nystagmus (n=3)
· Perverted Head Shaking Nystagmus (n=3)
· Disjunctive torsional nystagmus (n=2)
3) Brain imaging including DWI may not detect DMI in about a half of the patients at initial presentation with AVS.
· Negative MRI in 11/18 (10 with 1.5 and one with 3.0-T MRIs) within 10 days of symptom onset (median=one day, IQR=0-3 days)
4) Patients with DMI usually show neurological deterioration during the acute phase, but long-term prognosis is excellent.
5) Most patients had comorbid vascular risk factors and about a half of them had a stroke etiology other than small artery disease.
· Small artery disease n=10
· Large artery disease n = 7
· Vertebral dissection n = 1
It is important for physicians to recognize symptoms of dorsal medullary infarction as they can often be subtle. The most challenging presentation will be that of isolated vestibular symptoms, highlighting the importance of obtaining a through history for risk factors and examination.
Schematic illustration of the neural structures involved in patients with dorsal medullary infarction. AN=abducens nucleus; HN=hypoglossal nucleus;
ICP=inferior cerebellar peduncle; IVN=inferior vestibular nucleus; LVN=lateral vestibular nucleus; MLF=medial longitudinal fasciculus; MVN=medial vestibular nucleus; NPH=nucleus prepositus hypoglossi