FFS: Lateral medullary syndrome

History

Adolf Wallenberg (1862-1949), a German neurologist, described the syndrome in 1895 and published a precise anatomical description in 1901. However, the first recorded case was by Gaspard Vieusseux (1746-1814), who described his own symptoms at a medical meeting in Geneva in 1808.

---

Anatomy

The lateral medulla contains:

1. Motor nuclei for cranial nerves IX, X, and XI.
2. Sensory nucleus (nucleus solitarius) for cranial nerves VII, IX, and X.
3. Trigeminal sensory nucleus, mainly in the pons but extending through the brainstem.

Note: The hypoglossal and dorsal vagal nuclei are in the medial medulla.

---

Pathophysiology

The syndrome results from occlusion—commonly thrombosis or embolism, rarely dissection—of vessels supplying the lateral medulla and infero-lateral cerebellum.

Arterial supply includes:

• Vertebral artery branches
• Posterior inferior cerebellar artery (PICA) — supplies the dorsal lateral medulla and posterior medial cerebellum

Most cases are due to vertebral artery occlusion; less often due to PICA occlusion.

---

Clinical features

Symptoms

Typically acute onset of:

• Vertigo
• Vomiting
• Dysphagia
• Dysarthria
• Ataxia

Signs

Ipsilateral findings	Contralateral findings
Horner syndrome (ptosis, miosis, anhidrosis)	Spinothalamic loss (pain/temp) in limbs
Cerebellar signs, nystagmus
Cranial nerves IX, X palsy (palatal paralysis, loss of taste posterior 1/3 tongue)
Trigeminal spinothalamic loss in the face

---

Investigations

Blood tests:

1. FBC
2. U&Es / glucose
3. Coagulation profile
4. Others as clinically indicated

ECG — assess for atrial fibrillation

CT scan / CT angiogram / CT perfusion scan — per stroke protocols

MRI — best imaging for infarct definition

Echocardiography and carotid Doppler — if embolic source suspected

---

Management

1. ABC support
2. Initiate standard ischemic stroke protocols:
   • Consider thrombolysis and/or endovascular clot retrieval within 24 hours
3. Nil orally
4. IV fluids
5. Speech therapy referral
6. Antiplatelet therapy (e.g., aspirin via NGT if swallowing impaired)

---

Prognosis

Prognosis varies based on infarct size and location and timing of intervention.

• Early deaths can result from aspiration or sleep apnoea.
• Many recover significantly over weeks to months.
• Some may have lasting neurological deficits.

---

Appendix 1

---

References

Publications

• Kim JS, Lee JH, Suh DC, Lee MC. Spectrum of lateral medullary syndrome. Correlation between clinical findings and magnetic resonance imaging in 33 subjects. Stroke. 1994 Jul;25(7):1405-10.
• Brazis PW, Masdeu JC, Biller J. Localization in Clinical Neurology. 8e 2021
• Fuller G. Neurological Examination Made Easy. 6e 2019
• O’Brien M. Aids to the Examination of the Peripheral Nervous System. 6e 2023

FOAMed

• Hong L. Wallenberg Syndrome. LITFL
• Cadogan M. Horner Syndrome. LITFL
• Coni R. Neuro 101: Brainstem. LITFL
• Coni R. Neuro 101: Cerebral Hemispheres. LITFL
• Nickson C. Brainstem lesions. LITFL
• Nickson C. Stroke Thrombolysis. LITFL