Extradural tumors or tumors of the spine

Metastasis

75% of all patients with malignant tumors are affected by vertebral metastases. The most commonly reported neoplasms that cause vertebral metastases are: lung, breast, prostate, kidney, thyroid, and colon. The vertebral body is usually the starting point for metastasis growth. 95% of all spinal metastases are extradural.

Distribution

Lumbar: 22%

Thoracic: 70%

When the intervertebral disc is affected by severe degeneration, this may cause the onset of a condition called lumbar instability which is distinguished as:

A) Micro-instability of the spine: when the spine maintains its correct alignment, but the degenerated disc causes micro movements of the vertebrae that slide between each other, with consequent inflammation of the disc plate or of the vertebral joint and onset of back pain.

Stenosis is a narrowing of the spinal canal. Some people are born with a certain degree of stenosis, but more commonly it is the result of degenerative processes in the osteo-ligament structures that occur during physiological aging.

As this pathological condition progresses, the spinal canal that hosts the nerve roots and the spinal cord gradually narrows, and exerts pressure on them.

An intervertebral disc is a fibro-cartilaginous joint between adjacent vertebrae. Like a shock absorber, it provides stability and at the same time dynamism to the entire vertebral column.

It is formed by a central part, called nucleus pulposus, made of almost 90% water, and an outer concentric ring called annulus fibrosus, which surrounds and contains the nucleus pulposus.

In order to understand the pathophysiology of hydrocephalus, it is necessary to mention some brief anatomical notes.

The central nervous system (brain and spinal cord) is immersed in the Cerebrospinal fluid (CSF) (spinal fluid), which performs various functions, some of which are: mechanical protection and enabling the exchange of substances with the nervous system.

Syringomyelia is the development of a fluid-filled cyst within the spinal cord. When syringomyelia extends to the medulla oblungata it is referred to as syringobulbia. The most common cause of syringomyelia is Chiari Malformation. Other etiologic factors include hydrocephalus, vertebral trauma, medullary tumors and arachnoiditis. Syringomyelia, secondary to the malformation of Chiari 1, generally interests the cervical or cervical-dorsal marrow; more rarely it affects the whole spinal cord (“holocord” syringomyelia).

Chiari Malformation (CM) is a pathology of the posterior cranial fossa, in which the cerebellum and the brainstem are normally contained. CM is characterised by an “encumbrance” of the neural structures in the area of the passage between cranium and spine and by a reduced size of the posterior cranial fossa. The cerebellar tonsils and the brainstem are therefore displaced through a small opening, called the foramen magnum, in the spinal cavity.

Neurovascular conflicts include a set of syndromes caused by the compression of cranial nerves, in general in correspondence with their entry point into the brainstem (root entry zone or REZ). 

The REZ is the point in which the sheath (myelin) of central origin (oligodendrocytes) transforms into peripheral myelin (Schwann cells).

Hemifacial spasm is a disorder characterised by a unilateral, involuntary and intermittent contraction of the facial muscles.

The facial nerve controls the muscles of facial expressions (forehead, eye, neck, and cheeks).

Neurovascular conflicts include a set of syndromes caused by the compression of the cranial nerves and generally corresponding to their entry point into the brainstem (root entry zone or REZ).

The REZ corresponds to the point in which the sheath (myelin) of central origin (oligodendrocytes) is modified into peripheral myelin (Schwann cells).