Management of Intracranial Tumors and the Basic Pathogenesis of Hydrocephalus

Tumors that invade the base of the skull from below
Nasopharyngeal carcinoma infiltrates the base of the skull to produce paralysis of several cranial nerves arising from the medulla and Pons. Glomus jugulare tumors arise from glomus tissue embedded in the external coat of the jugular vein. These tumors may grow into the jugular foramen leading to pressure effects on the VIII, XII, IX, X and VII cranial nerves. Glomus tumors give to intense pain. Erosion of the jugular foramen can be demonstrated by X-ray.

Secondary deposits
Carcinomas of the lungs and breast are prone to produce cerebral metastases. Other primaries include carcinomas of the Kidneys and alimentary tract. Acute lymphatic leukemia and to a lesser extent acute myeloid leukemia may produce lesions in the central nervous system. Lymphomas also may produce neurological manifestations by infiltration.

management of intracranial tumors
Early diagnosis is very essential. A high index of clinical suspicion is absolutely essential to plan the appropriate investigation. Advent of CT has revolutionized the diagnosis and early detection is possible in the vast majority of cases. Treatment consists of surgical removal wherever possible, radiotherapy or both. Palliative measures include radiotherapy, medical measures to relieve rasied ICT, anticonvulsants, and procedures to relieve obstructive hydrocephalus.

Hydrocephalus (Syn: Hydrencephalus)
Dilatation of the ventricular system of the brain due to accumulation of CSF is called hydrocephalus.This may be congenital or acquired. If the communication between the ventricular system and the subarachnoid space remains patent, it is called communicating hydrocephalus. If this communication is blocked, it is termed obstructive hydrocephalus. In some cases the hydrocephalus may be normotensive, i.e, the pressure in the ventricular systems may be normal, in others it may be raised.

In congenital hydrocephalus and those developing in early infancy, the fontanelles and skull sutures separate and the head is enlarged. The eyeballs are depressed and optic atrophy may develop. The brain and skull are thinned out. Percussion over the skull may give a cracked-pot note.

Causes of hydrocephalus developing in infancy:
1. Bleeding into the brain during delivery and subsequent adhesions.
2. Congenital absence of arachnoid granulations
3. Stenosis of the aqueduct
4. Improper development of the mantle layer of the brain. In the early stages of embryonal development, the ventricular system is relatively larger. As the mantle layer develops and the brain grows this relative disparity disappears. In conditions where the mantle layer does not develop normally, hydrocephalus persists.
5. Arnold-Chiari malformation.
6. Obstruction to the foramina of Magendie and Lushka. In Dandy Walker syndrome, the obstruction is congenital.

Course and prognosis: If the obstruction if not relieved, the condition progresses, Mental deficiency, paralysis, and convulsions may develop in many.

Treatment: Surgical procedures are available to divert CSF from the ventricles and relieve tension using suitable valves. In ventriculo-peritoneal shunt, the CSF is diverted into the Peritoneum; in Ventriculo-atrial shunt the CSF is diverted into the right atrium, Ventriculo-sinus shunt- the sagital sinus; and then the theco-peritoneal shunt- draining the spinal subarachnoid space into the peritoneum.