Microsurgical considerations of the anterior spinal and the anterior-ventral spinal arteries

Medullary branches of the vertebral artery: microsurgical anatomy and clinical significance

BACKGROUND

Since the medullary arteries are of a great neurologic and neurosurgical significance, the aim was to perform a detailed microanatomic study of these vessels, as well as of the medullary infarctions in a group of patients.

METHODS

The arteries of 26 halves of the brain stem were injected with India ink and gelatin, microdissected and measured with an ocular micrometer. Neurologic and magnetic resonance imaging (MRI) examinations were performed in 11 patients.

RESULTS

The perforating medullary arteries, averaging 6.7 in number and 0.26 mm in diameter, most often originated from the anterior spinal artery (ASA), and rarely from the vertebral (VA) (38.5%) and the basilar artery (BA) (11.6%). They supplied the medial medullary region. The anterolateral arteries, 4.8 in number and 0.2 mm in size, most often arose from the ASA and PerfAs, and nourished the anterolateral region. The lateral arteries, 2.2 in number and 0.31 mm in diameter, usually originated from the VA and the posterior inferior cerebellar artery (PICA). They supplied the lateral medullary region. The dorsal arteries, which mainly arose from the PICA and the posterior spinal artery (PSA), nourished the dorsal region, including the roof of the 4th ventricle. The anastomotic channels, averaging 0.3 mm in size, were noted in 42.3%. Among the medullary infarctions, the lateral ones were most frequently present (72.8%).

CONCLUSION

The obtained anatomic data, which can explain the medullary infarctions symptomatology, are also important in order to avoid damage to the medullary arteries during neurosurgical and neuroradiologic interventions.

Role of the Cervical Anterior Spinal Artery in the Endovascular Treatment of Vascular Diseases: Bystander, Accomplice, Victim, or Friend?

The cervical anterior spinal artery (ASA) is a very important artery arising from the intracranial vertebral artery (VA). It can play different roles in endovascular treatment (EVT) of spinal vascular diseases. The current understanding of these roles is incomplete; therefore, we performed this review. We found that cervical ASA can be involved in many spinal vascular diseases, such as arteriovenous fistula (AVF), arteriovenous malformation (AVM), and aneurysm, and can serve as a collateral channel in proximal VA occlusion. In AVF and AVM, when the cervical ASA is involved, it often plays the role of an accomplice or victim because it acts as the feeder or as a bystander that does not provide blood flow to the AVF and AVM. In cervical ASA aneurysm, the ASA is a victim. During EVT of VA aneurysms or stenoses, the cervical ASA ostia can be covered or occluded, resulting in ASA ischemia. In this situation, the ASA is a victim. In VA occlusion or the subclavian steal phenomenon, the cervical ASA can serve as a collateral channel to provide blood flow to the posterior circulation. In this case, the ASA plays the role of a friend. According to the role of the cervical ASA in spinal vascular diseases, EVT should be determined “case by case.” Most importantly, when EVT is performed to treat these diseases, the cervical ASA axis must be preserved. Therefore, understanding the role of the cervical ASA in spinal vascular diseases is crucial.

[A case of bilateral medial medullary and left tegmentum of pontine infarction in whom DSA-MR fusion imaging identified infarct-relevant arteries]

We herein reported a patient with acute ischemic stroke in the bilateral medial medullary and the left tegmentum of the pons who presented with various neurological symptoms. Fusing digital subtraction angiography (DSA) and MRI (DSA-MR fusion imaging) could reveal the infarct-relevant arteries. A 41-year-old male presented with headache, bilateral arm's dysesthesia, quadriplegia, left Horner's syndrome, upbeat nystagmus, internuclear ophthalmoplegia and left peripheral facial paralysis. Diffusion weighted MRI (DWI) revealed the high intensity lesion in the bilateral medial medullary and the left tegmentum of the pons. MRA showed right vertebral artery (VA) occlusion. A high intensity on T₁ weighted imaging was shown on the right VA vessel wall. DSA-MR fusion imaging revealed the anterior spinal artery (ASA) occlusion proximal to the infarction. The stenosis was located at the origin of the right VA perforating branch distributing into the infarct lesion. The steno-occlusive lesion of ASA and VA perforating branch due to VA dissection resulted in infarction in the pontomedullary junction and caused various neurological symptoms. DSA-MR fusion imaging would prove the radiological anatomy of infarct-relevant arteries and clarify the etiology of ischemic stroke.

Heart-Shaped Bilateral Medullary Pyramidal Infarction as a Pathognomonic Finding of Anterior Spinal Artery Occlusion

BACKGROUND

Unilateral anterior spinal artery (ASA) occlusion resulting in bilateral medullary pyramidal (BMP) infarction is a rare and devastating stroke subtype. We present two cases highlighting the diagnostic and clinical challenges of BMP infarction.

METHODS

Case reports and literature review.

RESULTS

A 57-year-old man rapidly had severe vomiting and diarrhea 2 h after a meal. Examination revealed bulbar weakness and areflexic tetraplegia. Respiratory failure developed, requiring intubation and mechanical ventilation. Brain magnetic resonance imaging (MRI) showed a heart-shaped region of diffusion abnormality, characteristic of BMP infarction. Cerebral angiography showed an occluded left vertebral artery with unilateral left-sided origin of ASA. The patient required tracheostomy and percutaneous gastrostomy tube and was discharged to rehabilitation, with little improvement of his tetraplegia at 3-month follow-up. A 43-year-old woman presented to the emergency department with acute onset of lower-extremity paresthesia and history of upper respiratory infection 2 weeks prior. Initial examination findings included bulbar weakness, dysphagia, hyporeflexia, and generalized weakness. After admission, she had severe respiratory distress and required intubation. Lumbar puncture was evaluated for Guillain-Barré syndrome, but cerebrospinal fluid protein concentration was normal. Changes on diffusion-weighted MRI of the brain showed the characteristic heart-shaped BMP infarction, indicating occlusion of a unilateral ASA. She required tracheostomy and percutaneous gastrostomy tube placement, with no paralysis resolution.

CONCLUSION

Acute BMP infarction may present with flaccid tetraplegia mimicking neuromuscular disorders. When the infarction is recognized early, intravenous thrombolysis can be considered to reduce morbidity of this rare stroke subtype.

Anterior spinal artery infarction at the cervicomedullary junction

An 81-year-old right handed man presented with bilateral leg weakness. The patient had been previously independent and was medicated with warfarin for atrial flutter. He had longstanding type 2 diabetes, controlled by oral hypoglycemic medication. At presentation, he reported sudden onset left sided weakness with accompanying neck pain at 22h00 the previous evening. Pertinent findings on neurological examination included a left pronator drift and profound left leg weakness with unsustained antigravity strength. Deep tendon reflexes were brisk throughout but absent at the ankles and there was a left extensor plantar response. Cranial nerve and sensory examinations were normal.