Evolving hemimedullary syndrome: A case report

Abstract

Hemimedullary syndrome (HS) is a rare type of medullary infarction characterized by simultaneous infarction of the lateral and medial medulla oblongata, presenting with clinical features of both Wallenberg and Dejerine syndromes. There are only a few reports of HS in the literature, and relevant information on clinical treatment and outcomes is scarce. Here, we report a patient with evolving HS who was treated by intravenous thrombolysis and mechanical thrombectomy.

Introduction

Hemimedullary syndrome (HS) is a cerebrovascular disease characterized by lesions in both the medial and lateral medulla oblongata. ¹ This hemi-infarction of the medulla causes a constellation of clinical signs and symptoms associated with both the lateral and medial medullary syndromes and typically results from occlusion of an intracranial vertebral artery. Reports of HS are relatively rare. ² Here, we present a case of HS and a possible treatment approach.

Case report

A woman in her 50s with a history of hypertension was admitted to the Emergency Department of the Affiliated Hospital of Tianjin Academy of Traditional Chinese Medicine, Tianjin, China, in September 2023. She presented with numbness and weakness in the left limbs, accompanied by vertigo, nausea, and vomiting for 4 h. Neurological examination upon admission revealed right-sided tongue deviation, grade 4 muscle strength in the left lower extremity, and diminished sensory perception in the left limb, affecting both light touch and pinprick sensation. Both the right finger-to-nose test and the heel-knee-shin test indicated instability. Her National Institutes of Health Stroke Scale score was 6. ³ The patient’s clinical manifestations were consistent with medial medullary involvement, accompanied by decreased superficial sensation in the left limbs and right-sided ataxia, suggesting that the lateral medulla was also involved.

Laboratory tests results were as follows: D-dimer, of 4.91 mg/L; low-density lipoprotein cholesterol, 5.01 mmol/L; total cholesterol, 7.38 mmol/L; uric acid, 404 µmol/L; and random blood glucose, 9.87 µmol/L. An emergency cranial computed tomography (CT) scan revealed no acute abnormalities. At 4.5 h after disease onset, 50 mg of recombinant tissue-type plasminogen activator (rtPA; 0.9 mg/kg) was administered intravenously for thrombolytic therapy. At 10 h after rtPA administration, the patient became agitated and developed dysphagia and right-sided Horner syndrome. After a repeat head CT to exclude hemorrhage, the patient underwent digital subtraction angiography (DSA), revealing an occlusion of the right vertebral artery and posterior inferior cerebellar artery. Subsequently, percutaneous intracranial artery thrombectomy was successfully performed (Figure 1). After the surgery, the patient’s symptoms of visual rotation and nausea/vomiting improved as did her swallowing function. There were no respiratory system complications. On day 16 after mechanical thrombectomy, the follow-up magnetic resonance imaging (MRI) examination revealed an ischemic lesion in the medial region of the right medulla oblongata. No definite infarction signal was observed in the dorsolateral region of the medulla oblongata (Figure 2). The patient was prescribed aspirin and clopidogrel therapy. At the 6-month follow-up, her neurological function showed sustained improvement: complete recovery of swallowing function, a central tongue position, grade 4 muscle strength in the left limbs, improved ataxia, and a modified Rankin Scale score of 2. ⁴

Figure 1.

Cerebral angiogram of our patient with HS. (a) Before mechanical thrombectomy. DSA image shows right vertebral artery segment V4 with distal occlusion (anterior–posterior projection). (b) Vertebral artery recanalization after mechanical thrombectomy (anterior–posterior projection).

Figure 2.

DWI at 16 days after mechanical thrombectomy. Only lesions in the medial medulla oblongata are present.

Written informed consent was obtained from the patient for publication of this case report and accompanying images. The reporting of this study conforms to CARE guidelines. ⁵

Discussion

Because of the high concentration of nuclei and tracts in the medulla, the clinical presentation of medullary infraction is highly contingent on the precise location and extent of the lesion. The most well-known medullary syndromes are the lateral medullary (Wallenberg) syndrome and the medial medullary (Dejerine) syndrome, as well as two rare variants, the Babinski–Nageotte syndrome and the Céstan–Chenais syndrome, which are considered extensions of the Wallenberg syndrome that involve the more basal pyramidal tract. ⁶ HS (also known as Reinhold syndrome) is a specific, rare syndrome involving injury to both the medial and lateral medulla oblongata that was first described in 1984 by the German physician H. Reinhold. ⁷

HS presents with nearly all the features of Wallenberg syndrome and Dejerine syndrome.^8–10 Early reports typically described HS as a single-stage event, with simultaneous presentation of both lateral and medial symptoms. ¹¹ The first clinical presentation suggested involvement of medial medulla (ipsilateral deviation of the tongue and contralateral hemiparesis) with some extension into the lateral medulla (ipsilateral ataxia and decreased contralateral superficial sensation), followed 10 h later by other symptoms of Wallenberg syndrome, including dysphagia and right-sided Horner syndrome, probably due to lesion extension further into the lateral medulla. The main difference between HS and Babinski–Nageotte syndrome is clinically significant hypoglossal nerve palsy, which indicates a true HS. ⁷

Before further treatment, DSA confirmed occlusion of the right vertebral artery in the V4 segment. Clinical findings suggested the occlusion involved the branches of the vertebral artery supplying both the medial and lateral medulla. A limitation of our case was that the urgent need for reperfusion overrode preoperative MRI. The decision to perform thrombectomy was made because, despite treatment, the patient developed new brainstem signs (dysphagia, Horner’s syndrome), indicating clinical progression, while DSA confirmed a persistent occlusion of the right vertebral artery V4 segment, indicating a remediable vascular cause. This combination warranted rescue intervention. The subsequent diagnostic synthesis-integrating this vascular finding with the full clinical syndrome and the post-treatment diffusion-weighted imaging (DWI) pattern (medial core infarct with salvaged lateral penumbra)-provides converging evidence for initial involvement of both lateral and medial medulla.

The simultaneous infarction of the medial, paramedian lateral, and dorsal areas of the medulla oblongata observed in HS is due to a rare hemodynamic disorder of the vertebral arteries involving the anterior spinal branches of the vertebral artery, branches from the short and long lateral or transverse arteries of the vertebral artery, and the longest lateral arteries of the vertebral artery. ¹² Simultaneous infarction of these arteries is extremely uncommon. ⁷ In our case, DSA showed simultaneous right vertebral and posterior inferior cerebellar artery occlusion. Although intravenous rtPA thrombolytic therapy failed to prevent the clinical deterioration of neurological function, the symptoms of neurological deficits significantly improved following bridge mechanical thrombectomy, successfully avoiding the possibility of severe, permanent neurological dysfunction.^7,11,13 To our knowledge, this is the first report of successful mechanical thrombectomy as a rescue therapy for the rare condition of HS. Regarding the decision-making for endovascular treatment, although it exceeded the conventional 6-h time window and no CT or MR perfusion assessment was conducted, the patient’s symptoms of brainstem damage worsened, and there was persistent large vessel occlusion. For posterior circulation acute ischemic stroke, particularly in cases of clinical deterioration, the guidelines support aggressive endovascular intervention within a longer time window. ¹⁴ The successful recanalization and favorable clinical outcome of this case support the rationality of making decisions based on clinical and angiographic findings in specific situations. The pretreatment symptoms directly demonstrated that vertebral artery occlusion definitely caused acute ischemia across its entire vascular territory. The final MRI only showed a lesion in the medial part of the medulla oblongata, while the dorsal part of the medulla oblongata, acting as the ischemic penumbra, was saved, indicating successful vascular recanalization. The medial part of the medulla oblongata was the core infarction area, and this damage was irreversible. Notably, the worsening of our patient’s neurological status 10 hours after intravenous rtPA administration indicates that the initial ischemic process was dynamic and ongoing. Although we cannot directly observe the dynamic changes of the thrombus through continuous vascular imaging, the final infarction pattern on MRI provides indirect support for the occurrence of thrombus migration. For patients who experience neurological deterioration after intravenous thrombolysis and whose repeated routine CT scans do not detect bleeding, emergency vascular imaging should still be considered to identify persistent or developing large vessel occlusion and to be able to promptly implement endovascular salvage treatment.

Conclusion

This case provides important insights into managing similar cases of complex HS. The successful outcome demonstrates that for patients who have undergone strict selection and present with persistent large vessel occlusion in the posterior circulation and progressive clinical deterioration (even beyond the conventional time window), mechanical thrombectomy may still be a successful treatment approach and achieve good vascular recanalization and clinical outcomes. However, it must be emphasized that this report illustrates only one possible outcome. The safety and efficacy of reperfusion therapy for isolated V4 segment occlusion, particularly the risk of thrombus migration to the basilar artery, are not yet established by larger studies. Therefore, this treatment decision requires extremely careful individual risk assessment and should be validated by future research.