Executive Dysfunction After Fourth-Ventricle Epidermoid Cyst Resection

Fourth Ventricular Epidermoid Cyst - Case Series, Systematic Review and Analysis

Background:

Epidermoid cysts are extra-axial, pearly white avascular lesions mostly found in the cerebellopontine region. They are slow-growing and mostly become symptomatic when they attain significant size. They do occur at other anatomical locations, but fourth ventricle is a rare location. Three representative cases with their outcomes are described here.

Methods:

The systematic review was done with adherence to predefined criteria. The studied variables were age, gender, duration of symptoms (DOS), clinical features, hydrocephalus (HCP), extent of resection, postoperative complications, outcome, follow–up, and recurrence. Statistical analysis was done to identify predictive factors for outcome.

Results:

Final analysis included 58 studies containing 131 patients. The most common clinical feature was cerebellar dysfunction (93%). The most common cranial nerve involved was the abducens nerve (n = 37, 28.46%). Preoperative HCP was present in nearly a third (35%) of patients. The outcomes were not different with age (P = 0.23), gender (P = 0.74), DOS (P = 0.09), and HCP (P = 0.50). Improved outcomes were associated with total resections (P = 0.001), absence of preoperative cranial nerve dysfunctions (P = 0.004), and presentation with features of raised intracranial pressure (P = 0.005). Longer DOS (mean 76.74 months) was associated with significantly increased cranial nerve nuclei involvement (P = 0.03). Aseptic meningitis was reported in 14.5% of cases. Recurrences were infrequently reported (n = 9).

Conclusions:

Although the fourth ventricular epidermoid lesions are difficult to detect in an innocuous stage, when found, they should be extirpated early and totally, as a longer DOS leads to cranial nerve dysfunctions and suboptimal outcomes.

Verbal Adynamia and Conceptualization in Partial Rhombencephalosynapsis and Corpus Callosum Dysgenesis

Verbal adynamia is characterized by markedly reduced spontaneous speech that is not attributable to a core language deficit such as impaired naming, reading, repetition, or comprehension. In some cases, verbal adynamia is severe enough to be considered dynamic aphasia. We report the case of a 40-year-old, left-handed, male native English speaker who presented with partial rhombencephalosynapsis, corpus callosum dysgenesis, and a language profile that is consistent with verbal adynamia, or subclinical dynamic aphasia, possibly underpinned by difficulties selecting and generating ideas for expression. This case is only the second investigation of dynamic aphasia in an individual with a congenital brain malformation. It is also the first detailed neuropsychological report of an adult with partial rhombencephalosynapsis and corpus callosum dysgenesis, and the only known case of superior intellectual abilities in this context.

Fourth Ventricle Enlargement in Chiari Malformation Type I

OBJECTIVE

How Chiari malformation type I (CM-I) affects posterior fossa brain structures and produces various symptoms remains unclear. The fourth ventricle is surrounded by critical structures required for normal function. The foramen of Magendie can be obstructed in CM-I; therefore, fourth ventricle changes may occur. To test this hypothesis, we assessed fourth ventricle volume in CM-I compared with healthy controls.

METHODS

Using our database from 2007-2016, we studied 72 patients with CM-I and 30 age-matched healthy control subjects. Fourth and lateral ventricle volumes and posterior fossa volumes (PFV) were assessed and correlated with clinical signs and symptoms. Statistical analysis was performed.

RESULTS

Patients with CM-I had larger fourth ventricle volumes compared with control subjects (1.31 vs. 0.95 mL; P = 0.012). There were no differences in lateral ventricle volume or PFV. CM-I fourth ventricle volume was associated with tonsillar descent (P = 0.030). CM-I fourth ventricle volume variance was larger than healthy controls (F_71,29 = 8.33; P < 0.0001). Patients with CM-I with severe signs and symptoms had a significantly larger fourth ventricle than patients with CM-I with mild signs and symptoms (1.565 vs. 1.015 mL; P = 0.0002).

CONCLUSIONS

The fourth ventricle can be enlarged in CM-I independent of lateral ventricle size and is associated with greater tonsillar descent. Most importantly, fourth ventricle enlargement was associated with a worse clinical and radiographic presentation independent of PFV. Fourth ventricle enlargement can affect critical structures and may be a mechanism contributing to symptoms unexplained by tonsil descent. Fourth ventricle enlargement is a useful adjunct in assessing CM-I.