Spectrum of lateral medullary syndrome. Correlation between clinical findings and magnetic resonance imaging in 33 subjects

Ectatic vertebral artery associated medullary compression treated with microvascular decompression: a case report and review of literature

BACKGROUND

Vertebral artery compression syndrome is a rare condition defined as the clinical presentation of dizziness, vertigo, ataxia, dysarthria, dysphagia, progressive or acute paralysis, hemisensory loss, and cervical myelopathy secondary to compression of the medulla and upper spinal cord by the vertebral artery.

CASE DESCRIPTION

Here we describe a 57-year-old Mexican-American male with bulbar symptoms, positional vertigo, and diplopia. The patient's symptoms were managed through microsurgical decompression of the medulla utilizing a far lateral transcondylar approach. The patient reported clinical improvement on follow-up.

CONCLUSION

This case underscores the clinical complexity and heterogeneity of this rare neurovascular pathology and the importance of elucidating the pathophysiological mechanisms underlying the symptomatic presentation of vertebral artery compression syndrome.

Medial medullary infarction: clinical, radiological findings and long-term prognosis

BACKGROUND AND AIM

Medial medullary infarction (MMI) is a rare type of posterior circulation stroke. We aim to examine the clinical and radiological features, etiology, and prognosis of patients with MMI.

METHOD

MMI patients registered consecutively in the stroke databank of the Istanbul Medical Faculty between January 1999 and April 2022 were included in the study. Medullary lesions were rostrocaudally classified as rostral, middle, and caudal, and ventrodorsally as ventral, middle, and dorsal. The etiological classification was performed, and functional outcome was assessed based on the modified Rankin Scale (mRS). Overall survival was estimated using the Kaplan-Meier technique.

RESULTS

We examined 48 cases of MMI including 9 with bilateral MMI. There were 34 men (70%), and mean age was 62.9 (± 12.8) years. The median NIHSS score was 7 (IQR; 4.5-10.5). The most common symptom was motor dysfunction. The medullary lesions were located caudally in 4 patients, rostrally in 30, rostromedially in 10, and rostro-medio-caudally in 2 patients. On ventro-dorsal classification; unilateral lesions were found ventrally in 19, ventromedially in 11, and ventro-medio-dorsally in 4 patients. The median follow-up duration was 20 months (interquartile range (IQR); 1-60). According to the third-month mRS, 39% of the patients were considered to have a good prognosis.

CONCLUSION

The most common etiology was distal vertebral artery atherosclerosis. More than 50% of the patients could walk unassisted in the long-term follow-up, and stroke recurrence was infrequent. Patients with bilateral MMI had poor outcomes.

Exploring the neural mechanisms underlying achalasia: A study of functional connectivity and regional brain activity

BACKGROUND AND AIMS

The pathophysiology of achalasia, which involves central nuclei abnormalities, remains unknown. We investigated the resting-state functional MRI (rs-fMRI) features of patients with achalasia.

METHODS

We applied resting-state functional MRI (rs-fMRI) to investigate the brain features in patients with achalasia (n = 27), compared to healthy controls (n = 29). Focusing on three regions of interest (ROIs): the dorsal motor nucleus of the vagus (DMV), the nucleus ambiguus (NA), and the nucleus of the solitary tract (NTS), we analyzed variations in resting-state functional connectivity (rs-FC), fractional amplitude of low-frequency fluctuations (fALFF), and regional homogeneity (ReHo).

RESULTS

Achalasia patients demonstrated stronger functional connectivity between the NA and the right precentral gyrus, left postcentral gyrus, and left insula. No significant changes were found in the DMV or NTS. The fMRI analysis showed higher rs-FC values for NA-DMV and NA-NTS connections in achalasia patients. Achalasia patients exhibited decreased fALFF values in the NA, DMV, and NTS regions, as well as increased ReHo values in the NA and DMV regions. A positive correlation was observed between fALFF values in all six ROIs and the width of the barium meal. The NTS fALFF value and NA ReHo value displayed a positive correlation with integrated relaxation pressure (IRP), while the ReHo value in the right precentral gyrus showed an inverse correlation with the height of the barium meal.

CONCLUSIONS

Abnormal rs-FC and regional brain activity was found in patients with achalasia. Our study provides new insights into the pathophysiology of achalasia and highlights the potential of rs-fMRI in improving the diagnosis and treatment of this condition.

An In-Depth Analysis of Medullary Strokes at a Tertiary Care Stroke Center: Incidence, Clinical and Radiological Characteristics, Etiology, Treatment, and Prognosis

Introduction Medullary infarctions (MI) are a rare medical entity that is classified mainly as the more commonly lateral medullary infarcts (LMI) and the less common medial medullary infarcts (MMI). Lateral medullary syndrome, also known as Wallenberg syndrome, results when the medulla oblongata is affected and predominantly occurs secondary to atherosclerotic occlusion of the vertebrobasilar arteries. Previous studies have focused more on the anatomical, clinical, and topographical aspects of medullary infarcts. We describe the incidence of their presentation, radiological findings, etiology, treatment, and outcome at our comprehensive stroke center. Material and method This is a retrospective cohort study of 108 medullary stroke patients with confirmed clinical and radiological diagnoses of MI at Hamad General Hospital, Doha, between January 1, 2018 and December 31, 2020. We evaluated the electronic medical records of all stroke patients. Result During the selected period, a total of 2,912 ischemic strokes were reported. Of these, 843 (28.8%) were posterior circulation strokes. Only 108 (3.7%) patients had medullary strokes. Commonly encountered neurological features were dizziness (94.4%), limb ataxia (84.3%), dysarthria (44.4%), ipsilateral facial sensory loss (32.4%), headache (32.4%), contralateral limb sensory loss (25%), ipsilateral hemiparesis (24%), dysphagia (19.4%), and hiccups (13%). Most strokes reported were either minor (73% with National Institutes of Health Stroke Scale [NIHSS] 1-4) or moderate (26% with NIHSS 5-15). LMIs (87.9%) were the most common, followed by medial paramedian MI (10%). Twenty-five percent had extramedullary involvement, predominantly of the cerebellum (17.6%). Out of the total number of patients, 44 (40.7%) had large vessel atherosclerotic disease, followed by 41 (37.6%) whose stroke was due to small vessel disease, 15 (13.8 %) due to undetermined etiology, and 6 (5.5%) due to arterial dissection. Twenty-eight patients (25.4%) underwent 48-hour Holter monitoring, which detected atrial fibrillation in two patients (1.85%). The majority of patients (98.2%, or 106 patients) received antiplatelet therapy, while 68.5% (74 patients) received single antiplatelet therapy (SAPT), and 29.6% (32 patients) received dual antiplatelet therapy (DAPT). Noteworthy is that only 2.7% (three patients) received thrombolysis as an acute reperfusion therapy. Forty-seven percent (51 patients) were discharged home (mRS 0-2), and 51.9% (56 patients) were transferred to rehabilitation facilities. Follow-up assessments were performed at the stroke clinic for 57.4% (62) of the patients. The assessments found that 46 of the follow-up patients were functionally independent at that time (mRS 0-2). Conclusion This is the first large local study of medullary strokes to determine their frequency, presentation, etiology, treatment, and clinical outcome. Medullary strokes represent 3.7% of total ischemic strokes at our comprehensive stroke center. MI is rare and could present with a variety of neurological and non-specific symptoms that mimic common benign conditions. Prompt and early recognition with a high index of suspicion, the use of posterior NIHSS (POST-NIHSS), and urgent MRI-diffusion-weighted imaging (DWI) of the brain in acute settings can improve early diagnosis and the rate of reperfusion therapy. Further studies are needed to enable the early recognition and treatment of medullary infarcts.

Cricopharyngeal Myotomy; a Rescue Surgery for Dysphagia in Lateral Medullary Syndrome

Lateral medullary syndrome/Wallenberg syndrome, is a neurological disorder occurring due to ischemia in the lateral part of medullary oblongata resulting in wide range of symptoms. Dysphagia is usually exhibited in severe and persistent form in LMS. Hence timely intervention is mandatory before the patient further worsens. We describe a case of Lateral medullary syndrome with persisitent dysphagia who was managed successfully with cricopharyngeal myotomy.

Topographic Consideration on the Occurrence of Ipsilesional Facial Paresis in Lateral Medullary Infarction

INTRODUCTION

The purpose of this study was to identify course of the corticobulbar tract and factors associated with the occurrence of facial paresis (FP) in lateral medullary infarction (LMI).

METHODS

Patients diagnosed with LMI who were admitted to tertiary hospital were retrospectively investigated and divided into two groups based on the presence of FP. FP was defined as grade 2 or more by the House-Brackmann scale. Differences between the two groups were analyzed with respect to anatomical location of the lesions, demographic data (age, sex), risk factors (diabetes, hypertension, smoking, prior stroke, atrial fibrillation, and other cardiac risk factors for stroke), large vessel involvement on magnetic resonance angiography, other symptoms and signs (sensory symptoms, gait ataxia, limb ataxia, dizziness, Horner syndrome, hoarseness, dysphagia, dysarthria, nystagmus, nausea/vomiting, headache, neck pain, diplopia, and hiccup).

RESULTS

Among 44 LMI patients, 15 patients (34%) had FP, and all of them had ipsilesional central-type FP. The FP group tended to involve upper (p < 0.0001) and relative ventral (p = 0.019) part of the lateral medulla. Horizontally large lesion was also related to the presence of FP (p = 0.044). Dysphagia (p = 0.001), dysarthria (p = 0.003), and hiccups (p = 0.034) were more likely to be accompanied by FP. Otherwise, there were no significant differences.

CONCLUSION

The results of present study indicate that the corticobulbar fibers innervating the lower face decussate at the upper level of the medulla and ascend through the dorsolateral medulla, where the concentration of the fibers is densest near the nucleus ambiguus.

Highest resolution microCT scan of the human brainstem reveals putative anatomical basis for infrequency of medial medullary syndrome

Ischemic strokes affecting the medial medulla are exceedingly rare. The anatomical basis for the relative infrequency of this stroke syndrome has been largely uninvestigated due to historically coarse MRI and CT scan resolution. We capture and digitally dissect the highest-ever-resolution diffusible iodine-based contrast-enhanced CT (diceCT) scanned images of a cadaveric brainstem to map arterial territories implicated in medial medullary infarctions. 3D reconstructions show that within the anterior spinal artery territory previously implicated in medial medullary syndrome (MMS), there are numerous, small sulcal artery branches perforating the medulla within the anterior median fissure. These branches proceed in parallel through the anteroposterior depth of the medulla as expected; however, we also identify a network of intraparenchymal, rostrocaudal anastomoses between these sulcal perforating branches. This network of intraparenchymal sulcal artery anastomoses has never been described and may provide a significant collateral supply of oxygenated blood flow throughout the medial medulla. By ramifying deeper tissues, these anastomoses can help explain the infrequency of MMS.

Emotional facial palsy: an unusual and rarely explored neurological sign

The anatomy of the cortico-bulbar tract that drives voluntary movements of mimic muscles is well described. Some cases of facial palsy with inverse automatic-voluntary dissociation (emotional facial palsy; EFP) are reported in the literature. These cases suggested a completely independent path of the fibers whose lesion results in EFP. We aimed to review the clinical reports of EFP available in the literature to characterize the anatomical aspect of the fibers whose lesion results in the isolated impairment of spontaneous smiling. Cortico-pontine fibers that control spontaneous smiling arise from the medial surface of the prefrontal cortex and descend through the anterior limb of the internal capsule, thalamus, and brain steam, independently from those that control voluntary movement. The mesial temporal lobe, particularly the amygdala, plays a crucial role in the network driving emotionally evoked facial expressions. We would highlight the relevance of an unusual and rarely explored neurological sign that could be added to clinical examination in ruling out focal brain pathology, such as stroke, tumors, or multiple sclerosis.

A comparative analysis of 375 patients with lateral and medial medullary infarction

BACKGROUND

Few studies have compared the etiology and clinical features between pure lateral medullary infarction (LMI) and pure medial medullary infarction (MMI).

METHODS

All patients included were hospitalized at The First Affiliated Hospital and The Second Affiliated Hospital of Wenzhou Medical University from January 2015 to July 2020. Their risk factors, clinical manifestation, stroke mechanisms and short-term prognosis were analyzed retrospectively.

RESULTS

Among the 387 patients enrolled, 266 (68.7%) had LMI, 109 (28.2%) had MMI, and 12 (3.1%) (nine men and three women) had LMI plus MMI. We analyzed the 375 patients of LMI and MMI. The average ages of LMI and MMI were 59.4 years and 62.69 years, respectively. Univariate analysis and multivariable logistic regression was used to investigate the existing risk factors of MMI relative to LMI. Prior infarction, poor glycemic control, and atherosclerosis were more frequently associated with MMI than with LMI. The clinical manifestation was significantly different between LMI and MMI. We used modified Rankin Scale (mRS) score as the short-term prognostic evaluation criteria, and MMI appeared worse than LMI.

CONCLUSIONS

This study reveals that: (1) patients with MMI are older than those with LMI; (2) prior infarction, poor glycemic control, and atherosclerosis are independent risk factors of MMI than that of LMI; (3) the clinical manifestations of LMI and MMI are heterogeneous; (4) short-term prognosis of MMI is worse than LMI.

The course of facial corticobulbar tract fibers in the dorsolateral medulla oblongata

Background

The course of the corticobulbar tract (CBT) to the facial nucleus has been investigated by some previous studies. However, there are some unclear points of the course of the CBT to the facial nucleus. This study aimed to elucidate the detailed course of the CBT to the facial nucleus through the analysis of lateral medullary infarction (LMI) cases.

Methods

The neurological characteristics and magnetic resonance imaging findings of 33 consecutive patients with LMI were evaluated. The location of the lesions was classified rostro-caudally (upper, middle, or lower) and horizontally. Further, we compared the neurological characteristics between the groups with and without central facial paresis (FP).

Results

Eight (24%) patients with central FP ipsilateral to the lesion were identified. Dysphagia and hiccups were more frequently observed in the group with central FP than in the group without central FP. In patients with central FP, middle medullary lesions and those including the ventral part of the dorsolateral medulla were more frequently observed. Contrastingly, patients with lesions restricted to the lateral and dorsal regions of the dorsolateral medulla did not present with central FP.

Conclusion

The results of this study indicate that the CBT to the facial nucleus descends with the corticospinal tract at least to the middle portion of the medulla, and then ascends to the facial nucleus through the medial and ventral areas of the dorsolateral medulla after decussation.

[Blepharoptosis and dysarthria in a boy aged 2 years]

A boy, aged 2 years and 4 months, had a sudden onset of blepharoptosis of the right eyelid, accompanied by the mouth deviated to the right side, drinking cough, nystagmus, and developmental regression. Cranial MRI showed softening lesions formed after infarction of the right dorsolateral medulla oblongata, while head CT angiography showed no imaging of the proximal part of the V4 segment of the right vertebral artery. The child was diagnosed with dorsolateral medulla oblongata syndrome and was treated with gamma globulin to regulate immune function, with mannitol to reduce neuronal edema, with low-molecular-weight heparin sodium to improve local hypercoagulation of occluded blood vessels, with hyperbaric oxygen to improve local ischemia and hypoxia and promote the recovery of brain function, and with neuromuscular electrical stimulation to promote the recovery of neuromuscular function. Before discharge, only mild right ataxia and Horner syndrome remained. This article reports the first case of infantile dorsolateral medulla oblongata syndrome and provides experience for the diagnosis and treatment of the disease.

The Trouble with Swallowing: Dysphagia as the Presenting Symptom in Lateral Medullary Syndrome

BACKGROUND

Posterior circulation strokes account for approximately one-fourth of all ischemic strokes, but are frequently misdiagnosed by emergency providers. Current standard stroke screening tools such as the National Institutes of Health Stroke Scale and the Cincinnati Prehospital Stroke Scale are weighted toward anterior circulation stroke diagnosis. Lateral medullary syndrome, a type of posterior circulation stroke, can be particularly challenging to diagnose due to nonspecific presenting symptoms, such as dysphagia.

CASE REPORT

This report describes a 65-year-old man who presented with dysphagia, dizziness, and hoarseness. An initial neurological examination did not reveal any gross deficits, and imaging to evaluate for posterior circulation stroke was not obtained. The patient presented the following day with worsening symptoms, prompting imaging that revealed a large cerebellar ischemic infarction. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although dysphagia frequently occurs in lateral medullary syndrome, it is rarely the presenting symptom in the emergency department. In patients with cerebrovascular risk factors who present with dysphagia, a complete neurological examination should be performed and noncontrast computed tomography (CT) of the head should be obtained if a neurological deficit is appreciated. Due to their poor sensitivity, CT scans can frequently miss posterior circulation strokes, therefore magnetic resonance imaging should be considered if provider suspicion remains high. Emergency providers are encouraged to have a high level of suspicion for this rare but debilitating stroke syndrome to avoid misdiagnosis and delayed care.

Vestibular and Ocular Motor Properties in Lateral Medullary Stroke Critically Depend on the Level of the Medullary Lesion

Background: Lateral medullary stroke (LMS) results in a characteristic pattern of brainstem signs including ocular motor and vestibular deficits. Thus, an impaired angular vestibulo-ocular reflex (aVOR) may be found if the vestibular nuclei are affected.

Objective: We aimed to characterize the frequency and pattern of vestibular and ocular-motor deficits in patients with LMS.

Methods: Patients with MR-confirmed acute/subacute unilateral LMS from a stroke registry were included and a bedside neuro-otological examination was performed. Video-oculography and video-based head-impulse testing (vHIT) was obtained and semicircular canal function was determined. The lesion location/extension as seen on MRI was rated and involvement of the vestibular nuclei was judged.

Results: Seventeen patients with LMS (age = 59.4 ± 14.3 years) were included. All patients had positive H.I.N.T.S. vHIT showed mild-to-moderate aVOR impairments in three patients (ipsilesional = 1; ipsilesional and contralesional = 1; contralesional = 1). Spontaneous nystagmus (n = 10/15 patients) was more often beating contralesionally than ipsilesionally (6 vs. 3) and was accompanied by upbeat nystagmus in four patients. Head-shaking nystagmus was noted in seven subjects, ipsilesionally beating in six and down-beating in one. On brain MRI, damage of the most caudal parts of the medial and/or inferior vestibular nucleus was noted in 13 patients. Only those two patients with lesions affecting the rostral medulla oblongata demonstrated an ipsilaterally impaired aVOR.

Conclusions: While subtle ocular motor signs pointed to damage of the central–vestibular pathways in all 17 patients, aVOR deficits were infrequent, restricted to those patients with rostral medullary lesions and, if present, mild to moderate only. This can be explained by lesions located too far caudally and too far ventrally to substantially affect the vestibular nuclei.

Patient characteristics with negative diffusion-weighted imaging findings in acute lateral medullary infarction

BACKGROUND

Diffusion-weighted imaging (DWI) on magnetic resonance imaging (MRI) shows limited sensitivity in the acute-phase brainstem infarctions, including lateral medullary infarction (LMI), and the detailed characteristics of acute LMI patients with initially negative DWI-MRI findings have not been reported previously. Therefore, we aimed to investigate the differences in the backgrounds or symptoms of acute LMI patients with initially negative findings in standard axial DWI-MRI and those with positive findings.

METHODS

In this retrospective cohort study, we collected the data for 35 consecutive acute LMI patients who were hospitalized in our hospital from January 2011 to December 2018. Initial standard axial DWI-MRI was assessed, and the patients were divided into positive and negative groups. The characteristics of the two groups were compared, and the usefulness of additional thin-slice coronal DWI-MRI was also investigated.

RESULTS

Nine (26%) acute LMI patients were initially negative on standard axial DWI-MRI. The patients were independently associated with smoking history (78% vs. 23%, p = 0.021) and headache (78% vs. 31%, p = 0.046). Thin-slice coronal DWI-MRI showed positive findings in 50% of the patients with negative findings in standard axial DWI-MRI. All four patients with negative findings in both standard axial and thin-slice coronal DWI-MRI had smoking history and headache.

CONCLUSION

Smoking history and headache were associated with initial negative results in standard axial DWI-MRI in acute LMI. Additional thin-slice coronal DWI-MRI was sometimes useful in detecting acute LMI. Follow-up MRI is important for patients showing negative findings in initial DWI-MRI.

Topographic evaluation of medullary infarcts from the radiologist's point of view

PURPOSE

Despite considerable published information about the clinical-radiological correlation of medullary infarcts, no study has determined whether topographic evaluations are performed accurately among researchers. Our purpose in this study was twofold: to evaluate the topographic pattern of medullary infarcts on diffusion-weighted imaging by their radiological aspect, and to assess interobserver agreement on the topographic pattern.

METHODS

We retrospectively reviewed our imaging and clinical database for patients admitted to our radiology department between January 2014 and September 2019. Two radiologists evaluated the imaging studies independently. Consensus data were used in the analysis.

RESULTS

The retrospective review yielded 92 patients with medullary infarction. The affected vascular territories were lateral (n = 58), anteromedial (n = 28), posterior (n = 3), and anterolateral (n = 1). Two patients had hemimedullary infarction. The rostrocaudal levels of the medullary infarct were superior (n = 34), middle (n = 31), inferior (n = 4), superior-middle (n = 13), and middle-inferior (n = 10). The medullary infarcts were divided into two types: lateral (n = 62) and medial (n = 28). The affected vascular territories differed with rostrocaudal topography of medullary infarct (p = 0.003). Excellent interobserver agreement was found for type of medullary infarct, compared with moderate for vascular territory and fair for rostrocaudal topography. The anterolateral and posterior territories were the most often misdiagnosed, while the level with the most disagreements in rostrocaudal topography was middle.

CONCLUSION

The accurate topographic evaluation of a medullary infarct can be an important basis for investigating stroke etiology. However, correct topographic evaluation may not always be available and smaller territories such as anterolateral and posterior should be assessed carefully.

Which Factors Affect the Severity of Dysphagia in Lateral Medullary Infarction?

The purpose of this study was to identify factors associated with the severity of dysphagia after lateral medullary infarction (LMI). Patients with dysphagia after lateral medullary infarction who were admitted to a rehabilitation unit were included and divided into two groups (non-severe vs. severe). Severe dysphagia was defined as the condition showing decreased bilateral pharyngeal constriction without esophageal passage in a videofluoroscopic swallowing study that initially required enteral tube feeding. Their clinical data (age, sex, lesion side, duration of the illness, penetration-aspiration scale, functional oral intake scale, Modified Barthel index, National Institutes of Health Stroke Scale, and anatomical lesion on diffusion-weighted MRI) were compared to find differences between the two groups. Twelve patients had absence of esophageal passage among a total of 30 patients with dysphagia after LMI. Only anatomical lesion location and extent were significantly different between the two groups. The severe group showed posterolateral involvement in the upper and lower parts of the medulla. Otherwise, there were no significant differences between the two groups. The location and extent of involvement in the medulla were the most important factors associated with the severity of dysphagia after LMI.

Corneal Involvement in Wallenberg Syndrome: Case Report and Literature Review

A 47-year-old man with Wallenberg syndrome after a stroke in the territory of the left vertebrobasilar artery and posterior inferior cerebellar artery, presented a week later complaining of visual loss in the left eye. Examination showed corneal anaesthesia associated with a neurotrophic corneal epithelial defect. Corneal involvement secondary to trigeminal neuropathy in Wallenberg syndrome is not frequently reported and may lead to epithelial erosion and neurotrophic keratopathy. Clinicians should be aware that visual loss can occur from a neurogenic basis (e.g., Wallenberg syndrome) due to neurotrophic keratopathy. The use of cocaine, a potential cause of neurotrophic keratopathy, should also be suspected in the appropriate clinical scenario.

Lesion Topography and Its Correlation With Etiology in Medullary Infarction: Analysis From a Multi-Center Stroke Study in China

Objectives: The lesion topography of medullary infarction (MI) is heterogeneous and its correlation with stroke etiology remains elusive. We aim to clarify the lesion pattern of MI and to assess its correlation with stroke etiology.

Material and Methods: Of 1129 subjects with available DWI in SMART study (a multi-center trial concerning secondary stroke prevention in China) between April 2008 and December 2010, 43 patients with DWI confirmed MI (3.8%) were retrospectively evaluated. Lesions were categorized as lateral and medial medullary infarction (LMI and MMI, 33 and 10 subjects respectively) at 3 levels rostro-caudally and correlated with the stroke etiology. Clinical profiles and long-term prognosis were analyzed.

Results: Large artery atherosclerosis, small vessel occlusion, cardiogenic embolism and artery dissection accounted for 29, 11, 1, and 2 infarcts, respectively. Large artery disease was the most common cause in LMI (24 of 33, 72.7%) whereas small vessel occlusion was not uncommon in MMI (5 of 10, 50.0%). Though the difference of infarct pattern between large artery atherosclerosis and small vessel occlusion was insignificant, two distinct lesion patterns were considered to be relevant: (1) Rostral MMI with continuous medial pontine infarctions were more likely attributed to small vessel occlusion than large artery atherosclerosis. Kameda et al. (2) MMI with ventral to dorsal extension were more often caused by large artery disease than small vessel occlusion. Median NIHSS at admission was 4. During a median follow-up of 17 months, 2 patients died and 2 experienced recurrent ischemic events, 39 of 41 subjects (95.1%) were functional independent (mRS 0–2).

Conclusions: This multi-center study demonstrates that MI has distinct lesion pattern depending on various stroke etiologies and mechanisms. Future investigations with larger sample size should establish the lesion pattern of MI and validate its correlation with the stroke etiology and mechanisms, which might improve stroke management.

Lateral Medullary Infarction with or without Extra-Lateral Medullary Lesions: What Is the Difference?

BACKGROUND

Lateral medullary infarction (LMI) is not an uncommon disease. Although lesions are usually restricted to the lateral medullary area, some patients have additional infarcts in other parts of the brain. The clinical features and prognosis of isolated LMI (pure LMI, LMIpr) have been investigated. However, it remains unclear whether clinical characteristics, prognosis and factors associated with prognosis differ between patients with LMIpr and those with additional lesions (LMI plus, LMIpl).

METHODS

Patients with LMI identified by MRI were enrolled. The demographic and clinical characteristics, in-hospital outcome (intensive care unit [ICU] admission, pneumonia and modified Rankin scale [mRS] at discharge), and long-term residual symptoms (vertigo/dizziness, sensory disturbances, dysphagia) and outcomes (occurrence of stroke, acute coronary syndrome [ACS], death, and mRS at follow-up) were compared between LMIpr and LMIpl patients. Factors associated with poor functional outcome (mRS 2-6) at the follow-up were analyzed.

RESULTS

Among 248 LMI patients, 161 (64.9%) had LMIpr and 87 (35.1%) had LMIpl. During admission, patients with LMIpl more frequently experienced ICU care, pneumonia and had a higher discharge mRS (3 vs. 2; p < 0.001) than LMIpr patients. The occurrence of stroke, ACS, frequency of death and functional outcome was not different during follow-up. However, residual neurologic symptoms such as dizziness (p = 0.002), dysphagia (p = 0.04) and sensory symptoms (p < 0.001) were more frequent in LMIpr than in LMIpl patients. In LMIpr patients, the rostral location of LMI was associated with poor functional outcome (p = 0.041), whereas in LMIpl patients, the presence of medial posterior-inferior cerebellar artery lesion was associated with good functional outcome (p = 0.030).

CONCLUSION

Although the short-term outcome is poorer in LMIpl than LMIpr patients, long-term residual symptoms are more common in LMIpr patients. The location of the LMI and extra-medullary lesion affects the long-term functional outcome of LMIpr and LMIpl patients respectively.

Clinical course and outcome in patients with severe dysphagia after lateral medullary syndrome

Background

The objective of this study was to investigate the clinical course and final outcome in patients afflicted with severe dysphagia following a diagnosis of lateral medullary syndrome (LMS).

Methods

The patients with severe dysphagia after LMS admitted to a rehabilitation unit were included and their respective clinical data were prospectively collected. The criteria of ‘severe dysphagia’ was defined as the condition that showed decreased pharyngeal constriction with no esophageal passage in a videofluoroscopic swallowing study (VFSS) and initially required enteral tube feeding. The data included VFSS findings, types of diet and postural modification, penetration-aspiration scale (PAS) and functional oral intake scale (FOIS).

Results

A total of 11 patients were included and VFSS was performed every 2 weeks after stroke onset. Esophageal passage began to show at an average 34.7 ± 18.3 days, and the patients were able to begin consuming a partial oral diet with postural modification. It was 52.2 ± 21.8 days till they were advanced to a full oral diet. PAS and FOIS were significantly improved over time.

Conclusions

Patients with severe dysphagia after LMS were able to tolerate a partial oral diet at about 5 weeks following onset, and they were advanced to a normal diet after 10 weeks. This clinical course might help in predicting the prognosis, as well as assist in making practical decisions regarding a rehabilitation program.

Lateral medullary infarction with cardiovascular autonomic dysfunction: an unusual presentation with review of the literature

PURPOSE

We report an unusual case of lateral medullary infarction presenting with orthostatic hypotension with pre-syncope without vertigo or Horner's syndrome.

METHODS

Case report with review of the literature.

RESULTS

A 67-year-old man presented with pre-syncope and ataxia without vertigo. Initial brain CT and MRI were normal. Neurological evaluation revealed right-beating nystagmus with left gaze, vertical binocular diplopia, right upper-extremity dysmetria, truncal ataxia with right axial lateropulsion, and right-facial and lower extremity hypoesthesia. Bedside blood pressure measurements disclosed orthostatic hypotension. He had normal sinus rhythm on telemetry and normal ejection fraction on echocardiogram. A repeat brain MRI disclosed an acute right dorsolateral medullary infarct. Autonomic testing showed reduced heart rate variability during paced deep breathing, attenuated late phase II and phase IV overshoot on Valsalva maneuver, and a fall of 25 mmHg of blood pressure at the end of a 10-min head-up tilt with no significant change in heart rate. These results were consistent with impaired sympathetic and parasympathetic cardiovascular reflexes. He was discharged to acute rehabilitation a week later with residual right dysmetria and ataxia.

CONCLUSION

Lateral medullary infarctions are usually reported as partial presentations of classical lateral medullary syndrome with accompanying unusual symptoms ranging from trigeminal neuralgias to hiccups. Pre-syncope from orthostatic hypotension is a rare presentation. In the first 3-4 days, absence of early DWI MRI findings is possible in small, dorsolateral medullary infarcts with sensory disturbances. Physicians should be aware of this presentation, as early diagnosis and optimal therapy are associated with good prognosis.

Clinical Study of 27 Patients with Medial Medullary Infarction

BACKGROUND

Medial medullary infarction (MMI) is a rare ischemic stroke. Frequency of each neurological finding in MMI was different in each study.

METHODS

We retrospectively evaluated the medical records of patients with cerebral infarction who were admitted between March 1998 and October 2015. Patients in our study were diagnosed as having MMI by magnetic resonance image examination.

RESULTS

Of 2727 patients with ischemic stroke, 27 patients (20 males and 7 females) had MMI. The MMI was complicated by infarcts located in the pons (n = 6), cerebellum (n = 2), and lateral medulla (n = 1). One patient had bilateral MMI. Large-artery atherosclerosis was the most common etiology. Motor weakness of the extremities was the most common neurological finding. Diminished contralateral superficial sensation was more common than diminished contralateral vibratory sensation, and these 2 types of sensory disturbance were often complicated. The patients with large MMI significantly more often accompanied diminished touch (P = .003), pain (P = .017), and vibratory (P = .019) sensation. Facial weakness was shown more common contralateral to the infarcts than ipsilateral (n = 8 contralateral, n = 1 ipsilateral). Lingual palsy was also more common contralateral to the lesions (n = 3 contralateral, n = 1 ipsilateral). One patient alone fulfilled the classical Dejerine triad.

CONCLUSIONS

In MMI, motor weakness of extremities was commonly shown, and complication of diminished sensations indicated the large infarcts. As for facial weakness and lingual palsy, the supranuclear type was more prominent than the infranuclear type.

Comparison of dysphagia outcomes between rostral and caudal lateral medullary infarct patients

OBJECTIVE

A detailed knowledge of dysphagia outcomes in lateral medullary infarct (LMI) patients would enable proper establishment of swallowing therapy goals and strategies. However, little is known about the impact of infarct location on dysphagia outcomes in patients with LMI.

METHODS

Twenty patients with rostral LMI (rostral group) and 20 patients with caudal LMI (caudal group) participated in the study. All patients underwent swallowing therapy, which included compensatory treatments and strengthening exercises, for >3 months. Dysphagia evaluation was performed twice (during the subacute stage and six months after stroke onset) using videofluoroscopic swallowing studies. Dysphagia degree was assessed using the functional dysphagia scale (FDS), the penetration-aspiration scale (PAS) and the American Speech-Language-Hearing Association (ASHA) National Outcome Measurement System (NOMS) swallowing scale.

RESULTS

In the subacute stage, the rostral group had significantly higher FDS and PAS scores and a significantly lower ASHA NOMS score than the caudal group. Patients from both groups showed significant improvement from the initial evaluation to the six-month evaluation. There were no significant differences in these scale scores between the two groups at the six-month evaluation.

CONCLUSION

In the subacute stage, patients in the rostral group had more severe dysphagia than those in the caudal group. Dysphagia improved in both groups after 3-6 months of swallowing therapy. At six months after onset, there were no significant differences in dysphagia severity between the two groups. Recovery from dysphagia after LMI was observed regardless of the infarct location.

Central Nervous System Control of Voice and Swallowing

This review of the central nervous control systems for voice and swallowing has suggested that the traditional concepts of a separation between cortical and limbic and brain stem control should be refined and be more integrative. For voice production, a separation of the nonhuman vocalization system from the human learned voice production system has been posited based primarily on studies of nonhuman primates. However, recent humans studies of emotionally based vocalizations and human volitional voice production have shown more integration between these two systems than previously proposed. Recent human studies have shown that reflexive vocalization as well as learned voice production not involving speech involve a common integrative system. However, recent studies of nonhuman primates have provided evidence that some cortical activity vocalization and cortical changes occur with training during vocal behavior. For swallowing, evidence from the macaque and functional brain imaging in humans indicates that the control for the pharyngeal phase of swallowing is not primarily under brain stem mechanisms as previously proposed. Studies suggest that the initiation and patterning of swallowing for the pharyngeal phase is also under active cortical control for both spontaneous as well as volitional swallowing in awake humans and nonhuman primates.

Lateral medullary syndrome: a diagnostic approach illustrated through case presentation and literature review

Patients with lateral medullary syndrome classically present with crossed hemisensory disturbance, ipsilateral Horner syndrome, and cerebellar signs, all of which are attributable to infarction of the lateral medulla. However, variability in the presentation of this syndrome is the rule, as illustrated in this case presentation and literature review. We propose an approach to diagnosis and management of the lateral medullary syndrome and illustrate the need to integrate clinical information with an understanding of brainstem anatomy with the goal of determining which patients require urgent neuroimaging and acute stroke therapies. The importance of recognition of this condition in the emergency department is underscored by the association between lateral medullary infarction and vertebral artery dissection. With optimal therapy, the prognosis for recovery from lateral medullary syndrome is good.

Bilateral Symmetrical Idiopathic Necrotizing Encephalopathy: A New Syndrome in Sprague-Dawley Rats

This article describes the occurrence of a bilaterally symmetrical encephalopathy in Sprague-Dawley rats, which occurred over the period 2005 to 2012 in our laboratory in both untreated control rats and rats treated with different pharmacologically active compounds. The acute brain lesions consisted of degeneration/necrosis in the ventral areas of the brain mostly with little inflammatory response; in the more rare chronic cases there were numerous lipid-laden macrophages. The areas most consistently affected were the crus cerebri, the ventral midbrain, the pyramids, and the internal capsule. Other areas less frequently affected were the mammillary bodies, the fimbria, the olfactory tubercles, the optic tracts, and the ventral hippocampus. All available data, including clinical signs, gross pathology, clinical pathology, diet, breeding, and housing were collected and are presented. Our investigations did not elucidate the pathogenesis of the lesions, although the infarction-type changes are suggestive of a vascular etiology. To our knowledge, this particular lesion with its consistent distribution pattern has not been reported in the rat literature and its publication is therefore important to the toxicological pathology community, because an unbalanced group distribution in a toxicology study could potentially confound the safety assessment of a compound.

Dysphagia May Be an Independent Marker of Poor Outcome in Acute Lateral Medullary Infarction

BACKGROUND AND PURPOSE

The functional recovery after the lateral medullary infarction (LMI) is usually good. Little is known about the prognostic factors associated with poor outcome following acute LMI. The aim of this study was to identify the factors associated with poor long-term outcome after acute LMI, based on experiences at a single center over 11 years.

METHODS

A consecutive series of 157 patients with acute LMI who were admitted within 7 days after symptom onset was evaluated retrospectively. Clinical symptoms were assessed within 1 day after admission, and outcomes were evaluated over a 1-year period after the initial event. The lesions were classified into three vertical types (rostral, middle, and caudal), and the patients were divided into two groups according to the outcome at 1 year: favorable [modified Rankin Scale (mRS) score ≤1] and unfavorable (mRS score ≥2).

RESULTS

Of the 157 patients, 93 (59.2%) had a favorable outcome. Older age, hypertension, dysphagia, requirement for intensive care, and pneumonia were significantly more prevalent in the unfavorable outcome group. The frequencies of intensive care (13%) and mortality (16.7%) were significantly higher in the rostral lesion (p=0.002 and p=0.002). Conditional logistic regression analysis revealed that older age and initial dysphagia were independently related to an unfavorable outcome at 1 year [odds ratio (OR)=1.04, 95% confidence interval (95% CI)=1.001-1.087, p=0.049; OR=2.46, 95% CI=1.04-5.84, p=0.041].

CONCLUSIONS

These results suggest that older age and initial dysphagia in the acute phase are independent risk factors for poor long-term prognosis after acute LMI.

Clinical study of 46 patients with lateral medullary infarction

BACKGROUND

Lateral medullary infarction (LMI) exhibits a variety of clinical features. Various bulbar symptoms can occur in LMI.

METHODS

Neuroradiologic findings of 46 LMI patients were examined. Their infarcts were categorized into the rostral, middle, and caudal groups and were further subdivided into the anteromedial, anterolateral, lateral (L), and posterior regions.

RESULTS

The middle medulla was the most common site (27 patients). Most lesions affected the L region alone (25 patients). Dysarthria and facial palsy occurred significantly more frequently in the rostral group than those in the caudal group. Severe truncal ataxia was significantly more common in the caudal group than that in the rostral group. Twenty-five of the 28 patients with severe truncal ataxia displayed vestibular symptoms; otherwise, the other 3 patients showed absence of vestibular symptoms. Soft palate paralysis occurred at a significantly high frequency in the patients with dysphagia and hoarseness compared with the patients without these 2 symptoms. Segmental sensory disturbance occurred in 5 patients, 4 of whom exhibited atypical patterns.

CONCLUSIONS

The results of our comparisons between the rostral and caudal groups were consistent with those of previous studies. The presence of severe truncal ataxia without vestibular symptoms in LMI was atypical. An analysis of the bulbar symptoms indicated that the extent to which soft palate paralysis contributed to dysphagia was associated with the severity of ischemia in the nucleus ambiguus. The present study showed variability in clinical features of LMI, which was related to differences in the severity and the extent of ischemia in the lateral medulla.

Pure ipsilateral central facial palsy and contralateral hemiparesis secondary to ventro-medial medullary stroke

Medullary infarcts are occasionally associated with facial palsy of the central type (C-FP). This finding can be explained by the course of the facial corticobulbar (F-CB) fibers. It is believed that fibers that project to the upper facial muscles decussate at the level of the facial nucleus, whereas those destined to the lower facial muscles decussate more caudally, at the level of the mid or upper medulla. It has been proposed that the lower F-CB fibers descend ventromedially near the corticospinal tract to the upper medulla where they cross midline and ascend dorsolaterally. Accordingly, ventromedial medullary infarcts are expected to result in contralateral facial and limb weakness. We report a patient with a medial medullary infarct restricted to the right pyramid and associated with ipsilateral C-FP and contralateral hemiparesis. The neurological findings are discussed in light of the hypothetical course of the F-CB fibers in the medulla.

Laterality of bolus passage through the pharynx in patients with unilateral medullary infarction

Laterality of bolus passage in the pharynx is often seen in patients with medullary infarction. We evaluated the dominant side of bolus passage in the pharynx and investigated the factors that cause the passage to dominantly occur on the affected side. Forty-one patients (35 men and 6 women, 64 ± 9 years) with unilateral medullary infarction participated in this study. Bolus passage of 4 mL of thick liquid was evaluated in 3 regions (oropharyngeal, thyropharyngeal, and cricopharyngeal) and classified into 4 patterns (dominantly on the unaffected side [UAS], on both sides without clear laterality [BS], dominantly on the affected side [AS], and nonpassage of the bolus [NP]) by videofluoroscopic examination of swallowing. The bolus passages were as follows: UAS, BS, and AS occurred in 2, 32, and 7 patients in the oropharyngeal region; UAS, BS, and AS occurred in 5, 20, and 16 patients in the thyropharyngeal region; and UAS, BS, AS, and NP occurred in 11, 9, 10, and 11 patients in the cricopharyngeal region, respectively. In the thyropharyngeal region, the proportion of patients in whom the swallowing reflex occurred when the bolus was in the oropharynx and the proportion of patients with unilateral pharyngeal constrictor paralysis were greater in patients whose bolus passage was AS than in patients whose passage was BS. This suggests that the bolus predominantly passed through the affected side of the thyropharyngeal portion because of the asymmetry of pharyngeal contraction during swallowing in the early period after onset.

A crossed brain stem syndrome without crossed sensory symptomatology

Lateral medullary infarction (LMI) or Wallenberg syndrome is a type of brain stem stroke, more specifically, a type of crossed brain stem syndrome. LMI is a well-described entity with several documented typical characteristics including pain and temperature impairment in the ipsilateral to the lesion side of the face and the contralateral side of the trunk and limbs. We present a case of LMI which describes a patient who presented with atypical features of analgesia and thermanaesthesia on the contralateral side of the face and absence of sensory deficit on the ipsilateral side. We attributed this pattern of involvement to a lesion that affects the ventral trigeminothalamic tract and spares the dorsolateral part of the medulla where the spinal trigeminal tract and its nucleus lie. This case report highlights the presence of atypical presentations of LMI that may initially challenge the physician's diagnostic reasoning.

Prediction of dysphagia severity: an investigation of the dysphagia patterns in patients with lateral medullary infarction

OBJECTIVE

In order to identify the factors that influence the swallowing function in patients who develop Wallenberg syndrome (WS) following lateral medullary infarction (LMI), we examined various patient characteristics, including the passage pattern abnormality (PPA) of a bolus through the upper esophageal sphincter (UES).

METHODS

Fifty-four pure LMI patients with dysphagia participated in this study. PPA, defined as the failure of bolus passage through the UES corresponding to the intact side of the medulla, was identified during videofluorographic swallowing evaluations of each patient. On brain magnetic resonance imaging, the subjects' lesions were classified vertically into three levels and horizontally into seven levels in relation to the involvement of the ambiguous and/or solitary nuclei. Logistic regression analyses were performed for age, sex, PPA and the vertical and horizontal sites of the lesions.

RESULTS

In terms of severity, 15 subjects were categorized as having mild dysphagia, 26 subjects were categorized as having moderate dysphagia and 13 were categorized as having severe dysphagia. Subjects with cephalic lesions, greater vertical spread of the lesion and PPA were more likely to have severe dysphagia. PPA and a greater vertical spread of the lesion were related to the severity of the functional outcome (p<0.01). The horizontal extent of the lesion was not strongly related to the prognosis.

CONCLUSION

The presence of PPA in LMI patients is suggestive of abnormalities in the swallowing pattern and, in turn, damage to the medullary central pattern generator. The presence of PPA and a greater vertical spread of the lesion can be useful predictors of severe dysphagia.

Mechanism of medullary infarction based on arterial territory involvement

Background and Purpose

The blood supply to the medulla oblongata is distinct from that of other areas of the brainstem, and thus the mechanism underlying medullary infarctions may be distinct. However, few studies have investigated this.

Methods

Of 3833 stroke patients who were on the stroke registry between February 1999 and April 2008, those with medullary infarctions demonstrated on diffusion-weighted magnetic resonance imaging were enrolled. We analyzed the topography, the involved arterial territories, and the etiologic mechanisms of the lesions.

Results

In total, 142 patients were enrolled in the study. Bilateral medullary infarctions were rare (2.2%). Lesions involving the anteromedial or lateral territories were common in the upper medulla oblongata, whereas lateral territorial involvements were common in the middle and lower regions of the medulla oblongata. Significant stenosis (>50%) or occlusion of the vertebral artery was common (52.2%). Among stroke subtypes, large-artery atherosclerosis was most common (34.5%), while lacunae and cardioembolism were rare (3.5% and 4.2%, respectively). Vertebral artery dissection was frequent. The stroke mechanisms differed with the involved vascular territories. Large-artery atherosclerosis produced lesions in the lateral, anteromedial, and posterior territories. None of the cardioembolisms or other etiologies involved anteromedial or anterolateral territories, but all involved the lateral and/or posterior territories. Lacunar infarction was found only in the anteromedial and anterolateral territories.

Conclusions

The topography and mechanisms of infarctions involving the medulla oblongata are different with the involved arterial territories. These findings may be associated with the distinct pattern of arterial supply to the medulla oblongata.

Ataxia in patients with brain infarcts and hemorrhages

Gait and limb incoordination and ataxia are most often found in patients with brainstem and cerebellar infarcts and hemorrhages. Lesions involving the thalamus and the deep portions of the cerebral hemispheres also may cause ataxia accompanied by weakness and sensory symptoms. Patients who have lesions in the lateral medulla and inferior cerebellum often topple, lean, or veer when attempting to sit, stand, or walk. They list to the side or abruptly veer when walking. The affected limbs are often hypotonic. In pontine lesions, ataxia is accompanied by weakness and pyramidal tract signs as part of an ataxic hemiparesis syndrome. In lesions affecting the superior cerebellum and the brachium conjunctivum, limb dysmetria and overshoot and dysarthria predominate and gait ataxia is absent or slight and transient. Infarcts affecting the thalamus can cause gait instability and astasia with ataxia. Lateral thalamic lesions are characterized by hemisensory symptoms, extrapyramidal limb postures and dysfunction, and gait ataxia. Lesions that affect the posterior limb of the internal capsule and its afferent and efferent projections may also cause an ataxic hemiparesis syndrome, often with accompanying hemisensory abnormalities.

Lesion of the nucleus solitarius leads to impaired laryngeal sensation in bulbar palsy patients

BACKGROUND

In order to clarify the laryngeal sensation of bulbar palsy patients, we studied the relationship between laryngopharyngeal sensation and brainstem lesion in patients with dysphagia caused by bulbar palsy.

METHODS

Fifteen patients with lateral medullary infarction and dysphagia were included in this study. We performed laryngeal sensory test using the flexible laryngoscope and probes method previously developed by Yaguchi et al. The test sites included the right and left tip of the laryngeal surface of the epiglottis and bilateral arytenoid regions. Lesion sites were identified by magnetic resonance imaging and classified horizontally according to Kim's classification. We also used the anatomical atlas Cytoarchitecture of the Human Brain Stem to determine whether the lesions included the nucleus solitarius and nucleus ambiguus.

RESULTS

Eight cases had normal sensation and 7 cases had decreased sensation of the affected side of the epiglottis and arytenoid region. The lesions of decreased laryngeal sensation group were classified horizontally as large type or dorsal type and included the nucleus solitarius. Decreased laryngeal sensation was significantly correlated with lesions that included the nucleus solitarius (Fisher exact test; P = .026).

CONCLUSIONS

This study clarifies that patients with dysphagia caused by bulbar palsy may present with laryngeal sensory impairment of the affected side and laryngopharyngeal movement disorder. The important finding is that damage to both the nucleus solitarius and ambiguus cause dysphagia accompanied by decreased laryngeal sensation and that the lesions are relatively extensive and affect the middle level of the dorsal medulla.

Clinical review of 37 patients with medullary infarction

BACKGROUND

Clinical features of medullary infarction were compared between patients with lateral medullary infarction and medial medullary infarction

METHODS

Thirty-seven patients with medullary infarction (29 with lateral medullary infarction and 8 with medial medullary infarction) who were admitted to our center between April 1, 2007 and March 31, 2010 were examined. Background factors, neurologic signs and symptoms, imaging findings, cause of disease, and outcomes were assessed for patients with lateral and those with medial medullary infarction.

RESULTS

Examination of the clinical symptoms and neurologic findings suggested that among patients with medial medullary infarction, few demonstrated all of the symptoms of Dejerine syndrome at onset, and many had lesions that were difficult to locate based only on neurologic findings. Both lateral and medial medullary infarction were frequently caused by atherothrombosis. However, cerebral artery dissection was observed in 31% of patients with lateral medullary infarction and 12.5% of those with medial medullary infarction. In 13% of patients with lateral and 37% of patients with medial medullary infarction, magnetic resonance imaging diffusion-weighted images on the day of onset did not show abnormalities, and the second set of diffusion-weighted images confirmed infarction lesions. For lateral medullary infarction, a more rostral lesion location was correlated with a poorer 90-day outcome. For medial medullary infarction, a more dorsal lesion location was correlated with a poorer 90-day outcome.

CONCLUSIONS

The diagnosis rate of medullary infarction using imaging examinations at onset--particularly medial medullary infarction--is not necessarily high. The imaging examinations need to be repeated for patients who are suspected to have medullary infarction based on neurologic signs and symptoms.