Dorsoralateral bulbar syndrome, also known as Wallenberg syndrome or posterior inferior cerebellar artery syndrome, is the most common type of brainstem infarction and is one of the typical manifestations of posterior circulation ischemic stroke. This article lists 2 cases and comprehensively sorts out this syndrome, so if there is anything you haven't mastered, let's review it.
Let's take a look at two cases first~
Case 1
14-year-old boy presenting with vomiting, slurred speech and tilting to the right. Physical examination reveals dysarthria, right miosis, ptosis and gaze preference, right V2/V3 area and left tibial hyposensation, right lower facial paralysis, right tongue protrusion and right dysmetria. Neuroimaging showed brainstem stroke with vertebral artery dissection (Figs. 1-2).
Fig.1 Dorsal lateral wedge diffusion limited lesion of the right medulla oblongata
Figure 2 A: Decreased diameter of the right vertebral artery at the C2 level with irregular flow signal compared to the expected blood flow signal in the left vertebral artery [real arrow]; B: There is no obvious blood flow signal in the right vertebral artery [dotted arrow]; The results suggest right extracranial vertebral artery dissection
The patient was diagnosed with dorsolateral bulbar syndrome. The patient's gaze preference exemplifies ipsipulsion, an often forgotten sign of lateral bulbar syndrome due to damage to the contralateral olive cerebellar pathway that creates a cross in the medulla. The patient has ipsilateral facial weakness due to facial nerve fibers looping caudally into the medulla oblongata and exiting at the pontine medullary junction.
Case 2
A 55-year-old man with previous hypertension presented for 2 days with acute vertigo and unsteady standing. Patients report a spinning sensation and a tendency to fall to the right. In addition, the patient also had symptoms of nausea and blurred vision, but denied hearing loss or tinnitus.
The patient's blood pressure was 160/100 mmHg on admission, and the physical examination revealed spontaneous left-jerk nystagmus, which was enhanced with removal of the eyeball, worse when looking left, and changed to right nystagmus when looking to the right; After 15 seconds of horizontal shaking of the head, the nystagmus becomes a right jump; The head shake test is negative. In addition, the patient has Horner syndrome on the right side, decreased pain and temperature sensation on the right side of the face and left side of the body, and an abnormal finger-nose test on the right side.
The patient's clinical presentation is consistent with that of acute vestibular syndrome and, based on physical examination, can be identified as central vestibular syndrome. The patient was clinically diagnosed with dorsolateral bulbar syndrome and confirmed by MRI acute infarction in the right posterior inferior cerebellar artery (PICA) supply area, including the right lateral medulla oblongata and inferior cerebellum (Fig. 3).
Fig.3 The MRI results of the patient showed acute infarction involving the lateral medulla oblongata and the middle and lower cerebellum, and the right vertebral artery was not visible on angiography
Seeing this, have you begun to review the knowledge related to dorsolateral bulbar syndrome? The following is a comprehensive review of this syndrome, see what you haven't mastered, come and review it.
What is dorsolateral bulbar syndrome?
Dorsoralateral medullary syndrome refers to a series of clinical syndromes caused by posterior inferior cerebellar artery (PICA) or/and vertebral artery lesions, and in 1895, Germany neurologist Adolf Wallenberg described the clinical manifestations of PICA. A second case was reported in Wallenberg in 1901 and autopsy proved to be due to thrombosis in the initial segment of the posterior inferior cerebellar artery. The posterior inferior cerebellar artery is one of the sites of thrombosis or embolism in clinical practice, and thrombosis or embolism of the posterior inferior cerebellar artery is mainly manifested as avascular necrosis of the dorsolateral part of the medulla.
Dorsoralateral bulbar syndrome is the most common posterior circulation ischemic stroke syndrome, accounting for about 20% of all ischemic stroke patients, and about half of them manifest as this syndrome. In contrast, it is more common in male patients. Atherosclerosis of the large arteries is caused in 75% of patients, cardioembolism in 17%, and vertebral artery dissection in 8%. In younger patients, vertebral artery dissection is the most common cause.
What are the typical clinical presentations?
Patients with typical dorsolateral bulbar syndrome are usually older patients with vascular risk factors and, like any acute stroke syndrome, have an acute-onset. The most common symptoms are dizziness with vertigo, unsteady gait with imbalance, hoarseness, and difficulty swallowing. Symptoms usually last for a few hours or even days. Often, the symptoms associated with the syndrome are not noticeable and are therefore often misdiagnosed or missed clinically. As in case 2, the physician should consider the possibility of dorsolateral bulbar syndrome.
It's rare for a patient to show all the features of the syndrome intact, but in most cases, a portion of the clinical presentation is sufficient for the doctor to confirm the diagnosis. Typical clinical manifestations may include:
1. Symptomatic characteristics of the affected side
➤ Damage to the vestibular nerve nucleus – vertigo with nystagmus (nystagmus usually in the direction of the gaze), nausea and vomiting, and sometimes intractable hiccups;
➤ Sympathetic nerve fiber damage - Horner syndrome;
➤ Damage to the spinocerebellar tract and rope – ipsilateral cerebellar ataxia in which the body tends to fall to the ipsilateral side;
➤ Damage to the spinal tract nucleus of the trigeminal nerve – facial pain and numbness, impaired sensation;
➤ Suspected nucleus, nucleus solitary tract damage – dysphagia, hoarseness, choking on water, impaired sense of taste, soft palate paralysis, decreased gag reflex.
2. Symptomatic characteristics of the unaffected side
➤ Spinothalamic tract injury – decreased pain and temperature sensation in the limbs;
➤ Corticospinal tract is not involved – Because the corticospinal tract is located ventrally, the patient has no or only mild weakness on the unaffected side.
In clinical diagnosis, crossover sensory deficits suggest that the patient's lesion is located in the medulla oblongata and involves the trigeminal spinal nucleus and spinothalamic tract, which is key to diagnosis. Patients with dorsolateral bulbar syndrome presenting with pure sensory deficits have been reported in the past. In addition, patients with this syndrome are usually unconscious, but there are patients who do have impaired consciousness, which may be due to the gradual increase in edema after cerebellar infarction, compression of the brainstem, and impaired cerebrospinal fluid circulation.
If the patient lacks typical clinical manifestations, some scholars have suggested that when the patient meets the following two conditions, it can further indicate the possibility of dorsolateral bulbar syndrome:
(1) Suggesting that the lesion is in the medulla oblongata, dysarthria, and dysphagia must be one of them;
(2) Suggesting that the lesion is dorsolateral to the medulla oblongata, dysalgeal-temperature sensation, ataxia, and Homer's sign must be one of the three.
What diseases/symptoms do you need to differentiate from in clinical practice?
➤ Other causes of vertigo, particularly peripheral vertigo, such as acute labyrinthitis, may be younger, without any vascular risk factors, nystagmus is peripheral and unidirectional or rotatory, and may be associated with tinnitus without other brainstem signs. A positive head thrust test can help distinguish central causes, such as Wallenberg syndrome, from surrounding causes.
➤ Hemorrhagic stroke: rare, headache is more prominent.
➤ Acute demyelinating disease in multiple sclerosis: patients are typically younger, more female, and have a known history of demyelinating disease, acute recurrence/episode of neuromyelitis optica with posterior involvement in the posterior region. The patient is likely to be a young adult female, and signs may indicate more than one central nervous system (CNS) pathology.
The diagnosis is usually based on clinical examination and medical history. Neuroimaging, particularly MRI of the DWI sequence, is the best diagnostic method for confirming acute infarction in the subcerebellar region or dorsolateral medullary medulla oblongata in patients with suspected dorsolateral bulbar syndrome, and MRI can help rule out similar symptoms due to conditions such as demyelination. CT is greatly affected by skull artifacts, and the medulla oblongata is not clear, so the diagnostic value is not as good as MRI.
It is estimated that approximately 35% of posterior fossa strokes are not correctly diagnosed in the emergency department setting, and DWI sequences are also likely to be falsely negative for acute stroke. However, indirect cues from imaging studies can also be helpful in suggesting dorsolateral bulbar syndromes, including vocal cord paralysis, palate asymmetry, vertebral artery clots, and ocular bias that may suggest nystagmus (figure 4).
Fig.4 Imaging examination of a patient with dorsolateral bulbar syndrome. A: Vocal cord paralysis (arrows) on CT angiography; B: Co-ophthalmosis suggests nystagmus; C: Palate asymmetry (arrow); D: T2 sequence of MRI scan, blood clot visible in vertebral artery V4.
CT angiography or MR angiography can be very helpful in identifying sites of blockage and ruling out uncommon causes, such as vertebral artery anatomy. Electrocardiogram (ECG) can help rule out an underlying cause of atrial fibrillation. Checking serum electrolytes is also crucial.
How is it managed?
Patients with ischemic stroke causing dorsolateral bulbar syndrome should be managed similarly to other ischemic strokes and should follow the principle that "time is the brain". The goal of treatment is to reduce infarction and prevent any complications, with the ultimate goal of improving clinical management and prognosis. Management methods include:
➤ For patients who have the opportunity to complete revascularization, thrombolysis or endovascular therapy is performed, and the management of blood pressure, blood glucose, and deep vein thrombosis prophylaxis in the acute phase is basically the same as that of general ischemic stroke.
➤ It is important to note that hypotonic solutions should be avoided to reduce the risk of cerebral edema, and caution should be taken to prevent choking and aspiration as patients may have symptoms such as dysphagia.
In summary, dorsolateral bulbar syndrome has a better functional prognosis than most other stroke syndromes, and most patients return to a satisfactory level of daily activity, with the most common sequelae being gait instability. However, if the patient has poor respiratory and circulatory function, the prognosis is not good.
Bibliography:
[1] Lui F, Tadi P, Anilkumar AC. Wallenberg Syndrome. [Updated 2020 Jul 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020.
[2] Alexandra Kornbluh, Jamie-Dawn Twanow. Teaching NeuroImages: Adolescent Wallenberg syndrome with overlooked signs[J]. Neurology Nov 2018, 91 (20) e1949-e1950; DOI: 10.1212/WNL.0000000000006513.
[3] Gao Wen. Journal of Stroke and Neurological Diseases,2020,37(07):641-644.)
[4] Lee S H, Kim J S. Acute Diagnosis and Management of Stroke Presenting Dizziness or Vertigo[J]. Neurologic Clinics, 2015, 33(3):687.
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