Arcuate foramen is the presence of an additional bone arch in the structure of the first cervical vertebra, which restricts the movements of the vertebral artery and causes its compression syndrome. Kimberly’s anomaly is characterized by dizziness, tinnitus, unsteadiness of gait and coordination disorder, “flies” and darkening of the eyes, bouts of loss of consciousness and sudden muscle weakness. Possible motor and sensory disorders, the occurrence of TIA and ischemic stroke. Arcuate foramen is diagnosed by X-ray examination of the craniovertebral junction, magnetic resonance angiography, duplex scanning and ultrasound of the vessels of the head and neck. Vascular disorders, which are accompanied by the arcuate foramen, are subject to complex conservative treatment. Surgery for resection of an abnormal arch is performed only in severe cases.
Along with Chiari anomaly, platybasia and Atlanta assimilation, arcuate foramen refers to the so—called craniovertebral malformations – congenital structural disorders of the area of articulation of the skull with the first cervical vertebrae. According to some data, pathology occurs in 12-30% of people. Causing compression of the vertebral artery, disease is accompanied by chronic ischemia in the posterior parts of the brain. However, this situation does not always occur. By itself, the arcuate foramen is not a disease and its presence does not mean that it causes vascular disorders in the vertebral artery basin. When examining patients who have vertebral artery syndrome and arcuate foramen, only 25% have a causal relationship between the presence of an anomaly and the development of the syndrome.
The right and left vertebral arteries branch off from the corresponding subclavian arteries. Each vertebral artery runs along the cervical spine, being in the channel formed by the openings of the transverse processes of its vertebrae. Then it enters the large occipital foramen, thus entering the cranial cavity. The vertebral arteries and their branches form the so-called vertebro-basilar pool, which supplies blood to the part of the spinal cord in the cervical spine, the cerebellum and the brainstem. Coming out of the cervical canal, the vertebral artery bends around the cervical vertebra and passes horizontally in a wide bone furrow, where it can move freely with head movements. The bony arch, the presence of which is characterized by the arcuate foramen, is located above the bone furrow and restricts the movement of the vertebral artery in this place.
The arcuate foramen can lead to the development of vertebral artery syndrome in two ways: due to the activation of perivascular vegetative-irritative mechanisms of sympathetic innervation and due to reduced blood flow to the vertebral-basilar basin due to mechanical compression of the vertebral artery. Factors leading to the fact that the arcuate foramen becomes clinically significant are atherosclerosis, vascular wall damage in vasculitis, cervical spondyloarthrosis, osteochondrosis of the cervical spine, arterial hypertension, the presence of other craniovertebral malformations, scarring, traumatic brain injury or spinal injury with injuries in the area of craniovertebral junction. Shoulder injuries that cause damage to the vertebral artery limited by the bone arch by the whiplash mechanism can lead to the appearance of a clinical picture of vertebral artery syndrome in patients.
In neurology, there are 2 types of arcuate foramen. The first is characterized by the presence of a bony arch connecting the articular process of the atlas with its posterior arch. In the second variant, the arcuate foramen is represented by a bony arch between the articular process of the Atlas and its transverse process.
The arcuate foramen may be unilateral and may be observed on both sides of the first cervical vertebra. In addition, arcuate foramen may be complete and incomplete. A complete abnormal bone arch has the form of a semicircle, an incomplete bone arch is an arcuate outgrowth.
The clinical manifestations that accompany the arcuate foramen are due to a reduced blood flow to the posterior parts of the brain. As a result, patients experience noise in the ear or both ears (whistling, ringing, buzzing, hissing), flashing of “flies” or flickering of “stars” in front of the eyes, sudden transient darkening in the eyes. These symptoms increase with head turns. Since the arcuate foramen is accompanied by a violation of the blood supply to the cerebellum, dizziness and unsteadiness of gait occur, which can also be aggravated when turning the head. Against the background of an uncomfortable position of the head or overstrain of the neck muscles in the case of arcuate foramen, patients may experience bouts of loss of consciousness. There may be sudden muscle weakness, leading to a fall of the patient without loss of consciousness.
In cases of a more severe course, the arcuate foramen may be accompanied by headache, tremor of the arms and legs, nystagmus, coordination disorders, hypesthesia and / or muscle weakness of a part of the face or trunk, sensory and motor disorders of one or more limbs. Transient ischemic attacks may be observed in the vertebrobasilar basin. A particularly severe complication of the presence of the arcuate foramen is an ischemic stroke.
When treating a patient with symptoms of circulatory insufficiency in the vertebral-basilar basin of the brain, first of all, an X-ray of the skull and an X-ray of the spine in the cervical region are performed. The arcuate foramen, as a rule, is quite clearly visualized on lateral radiographs of the craniovertebral junction area. In the presence of ear noise, to exclude ENT pathology (cochlear neuritis, chronic otitis media, labyrinthitis), an otolaryngologist’s consultation, audiometry and other hearing studies may be required. The vestibular analyzer is also being examined (vestibulometry, electronistagmography, stabilography).
Since the identified arcuate foramen may not be the cause of vertebral artery syndrome, the neurologist needs to exclude other possible causes of vertebral-basilar insufficiency. Contrast angiography is able to detect thrombosis, arteriovenous malformation or aneurysm of cerebral vessels, compression of a vessel by a volumetric formation (tumor, cyst or abscess of the brain). To determine how clinically significant the arcuate foramen is, i.e. the degree of its influence on blood circulation in the vertebral-basilar basin allows the use of a number of hemodynamic studies: ultrasound of extracranial vessels, transcranial dopplerography, duplex scanning and magnetic resonance angiography of cerebral vessels. With their help, it is possible to identify the localization of compression of the vertebral artery and its dependence on the position of the head and neck in the case of this disease.
Arcuate foramen requires treatment in the presence of clinical and hemodynamic signs of circulatory disorders in the vertebro-basilar basin associated with this pathology. Patients who have an arcuate foramen should observe some precautions within the protective regime. In case of v, forced physical exertion, sharp near-extreme head turns, headstands, somersaults, sports activities and games related to head impacts (wrestling, football, gymnastics, etc.) should be avoided. When undergoing massage or manual therapy of the cervical spine, the patient should be warned by the masseur and the chiropractor that he has a arcuate foramen. The deterioration of the patient’s condition is a reason for immediate medical attention.
In most cases, the arcuate foramen, which leads to clinical manifestations of vascular insufficiency, is subject to conservative treatment. Vascular therapy is carried out aimed at improving cerebral blood flow (nicergoline, vinpocetine, vincamine, cinnarizine). According to indications, under the control of the coagulogram, drugs that improve the rheological properties of blood (pentoxifylline) are used in the case of arcuate foramen. Complex therapy also includes antioxidants, nootropics, neuroprotectors and metabolic drugs (piracetam, ginkgo biloba preparations, nicotinoyl-gamma-aminobutyric acid, meldonium).
Arcuate foramen is not currently an indication for surgical treatment. The need for surgical treatment may arise with a decompensated course of the vertebral artery syndrome, leading to severe circulatory insufficiency in the vertebral-basilar basin in the absence of sufficient collateral blood supply. Surgery for Kimberly’s anomaly consists in resection of the abnormal arch and mobilization of the vertebral artery. In the postoperative period, patients need to wear a Trench collar for a period of 2 to 4 weeks.