Neuro

Multiple sclerosis is the most common cause of an isolated sixth cranial nerve palsy due to a plaque in the brainstem.

The closest nerve to the eighth cranial nerve is the facial nerve; however, after the acoustic nerve, the most common nerve to be affected is the trigeminal nerve. There is a relative loss of higher tones in nerve deafness whereas lower tones are lost in middle ear deafness.

The most common presenting symptom of a posterior fossa mass is headache related to mass effect, or obstruction of cerebrospinal fluid (CSF) pathways.

Pilocytic astrocytomas (PAs) are the most common pediatric cerebellar neoplasm and occur at a mean age of 7 to 8 years.

The most common genetic anomaly in medulloblastoma is isochromosome 17q. The most common genetic alteration in ependymoma is loss of chromosome 22;

Hemangioblastomas are the most common posterior fossa lesion in adults but are rarer in the pediatric population.

Spinal cord ependymomas are the most frequent SCIMTs in adult patients.

Spinal cord astrocytomas represent more than 80% of the SCIMTs in children,43 and in adults astrocytomas are the second most common type of tumor.