Intracranial lipoma of the quadrigeminal region associated with complex partial seizures

Jacobian Mapping Reveals Converging Brain Substrates of Disruption and Repair in Response to Ethanol Exposure and Abstinence in 2 Strains of Rats

BACKGROUND

In a previous study using Jacobian mapping to evaluate the morphological effects on the brain of binge (4-day) intragastric ethanol (EtOH) on wild-type Wistar rats, we reported reversible thalamic shrinkage and lateral ventricular enlargement, but persistent superior and inferior colliculi shrinkage in response to binge EtOH treatment.

METHODS

Herein, we used similar voxel-based comparisons of Magnetic Resonance Images collected in EtOH-exposed relative to control animals to test the hypothesis that regardless of the intoxication protocol or the rat strain, the hippocampi, thalami, and colliculi would be affected.

RESULTS

Two experiments [binge (4-day) intragastric EtOH in Fisher 344 rats and chronic (1-month) vaporized EtOH in Wistar rats] showed similarly affected brain regions including retrosplenial and cingulate cortices, dorsal hippocampi, central and ventroposterior thalami, superior and inferior colliculi, periaqueductal gray, and corpus callosum. While most of these regions showed significant recovery, volumes of the colliculi and periaqueductal gray continued to show response to each proximal EtOH exposure but at diminished levels with repeated cycles.

CONCLUSIONS

Given the high metabolic rate of these enduringly affected regions, the current findings suggest that EtOH per se may affect cellular respiration leading to brain volume deficits. Further, responsivity greatly diminished likely reflecting neuroadaptation to repeated alcohol exposure. In summary, this unbiased, in vivo-based approach demonstrating convergent brain systems responsive to 2 EtOH exposure protocols in 2 rat strains highlights regions that warrant further investigation in both animal models of alcoholism and in humans with alcohol use disorder.

The Inferior Colliculus in Alcoholism and Beyond

Post-mortem neuropathological and in vivo neuroimaging methods have demonstrated the vulnerability of the inferior colliculus to the sequelae of thiamine deficiency as occurs in Wernicke-Korsakoff Syndrome (WKS). A rich literature in animal models ranging from mice to monkeys-including our neuroimaging studies in rats-has shown involvement of the inferior colliculi in the neural response to thiamine depletion, frequently accomplished with pyrithiamine, an inhibitor of thiamine metabolism. In uncomplicated alcoholism (i.e., absent diagnosable neurological concomitants), the literature citing involvement of the inferior colliculus is scarce, has nearly all been accomplished in preclinical models, and is predominately discussed in the context of ethanol withdrawal. Our recent work using novel, voxel-based analysis of structural Magnetic Resonance Imaging (MRI) has demonstrated significant, persistent shrinkage of the inferior colliculus using acute and chronic ethanol exposure paradigms in two strains of rats. We speculate that these consistent findings should be considered from the perspective of the inferior colliculi having a relatively high CNS metabolic rate. As such, they are especially vulnerable to hypoxic injury and may be provide a common anatomical link among a variety of disparate insults. An argument will be made that the inferior colliculi have functions, possibly related to auditory gating, necessary for awareness of the external environment. Multimodal imaging including diffusion methods to provide more accurate in vivo visualization and quantification of the inferior colliculi may clarify the roles of brain stem nuclei such as the inferior colliculi in alcoholism and other neuropathologies marked by altered metabolism.

Role of intraoperative squash smear cytology as a diagnostic modality in lipoma of quadrigeminal cistern

Quadrigeminal lipoma is a rare tumor that has been categorized as developmental malformation rather than a hamartoma or true neoplasm, due to its origin from abnormal persistence and mal-differentiation of meninx primitiva during the development of the subarachnoid cisterns. Reported admixture of adipose tissue with heterotopic elements also supports a developmental origin. Quadrigeminal lipomas are frequently asymptomatic and detected incidentally. Though a favorable clinical course is usually expected, recurrences may occur due to partial removal of lesions in close relation to vital structure. We describe the role of intraoperative squash smear cytology as a diagnostic aid in quadrigeminal cistern lipoma and an alternative to frozen sections that are technically difficult to obtain due to presence of lobules of fibro-adipose tissue. With radiological correlation, squash cytology can be an economical method for intraoperative diagnosis, pending subsequent histopathological confirmation.

Quadrigeminal plate cistern lipoma

Intracranial lipomas are rare benign neoplasms accounting for <0.1% of all primary brain tumours. Most lipomas were incidentally detected by autopsy or computed tomography (CT).These slow growing benign lesions are usually asymptomatic and rarely require surgery. We report the case of a 70-year-old Nigerian woman who presented with persistent headaches following involvement in a road traffic accident 20 days previously. CT demonstrated a quadrigeminal cistern lipoma with no evidence of raised intracranial pressure or compression of neural structures. Her headaches resolved with conservative care. We describe the CT findings with a brief review of the literature.

Non-febrile seizure associated with pericallosal lipoma

Intracranial lipoma is a very rare condition, with an incidence of less than 0.1% of all intracranial tumors. They are mostly localized in the pericallosal region. Pericallosal lipoma is an extremely rare tumor of the central nervous system and rarely gives any symptoms. A 6-year-old girl with an unexplained headache was admitted to the Pediatric Outpatient Clinic with complaints of non-febrile seizure. Her seizure was a complex-partial type. Biochemical tests for seizure etiology did not reveal any specific cause. Electroencephalography (EEG) revealed typical epileptic activity. Magnetic resonance imaging (MRI) gave images of a mass approximately 1 cm in diameter in the vicinity of corpus callosum splenium. Her seizures were kept under control with carbamazepine (400 mg/day) and indicators of neuromotor development were found to be normal throughout 24-month period of follow up. Even though it is a rare condition, pericallosal lipoma should also be taken into account in the differential diagnosis of non-febrile seizures in children.

Quadrigeminal cistern lipoma

Intracranial lipomas are rare benign congenital neoplasms accounting for 0.1 to 0.5% of all primary brain tumours. Approximately 50% are associated with other cerebral developmental disorders. These slow growing benign lesions are usually asymptomatic and rarely require surgery. We report the case of a 37 year old woman presented with signs of raised intracranial pressure. Computerized tomography and magnetic resonance imaging demonstrated a quadrigeminal cistern lipoma compressing the aqueduct of Sylvius. The patient underwent surgery and a distinct plane of cleavage between the lipoma and the adjacent neural structures was found, allowing total removal of the lesion. Postoperatively, the patient was relieved of her original symptoms but developed akinetic mutism which lasted for two weeks. Intracranial lipomas rarely become symptomatic and surgery is seldom required. If the lesion progresses and causes symptoms of raised intracranial pressure or compression of neural structures, surgical intervention is indicated. Total removal should not be attempted unless a plain of cleavage between the lesion and adjacent neural structures is present. Surgical manipulation should be minimised to avoid complications.

Angiolipoma of the right inferior colliculus: a rare central cause of hearing loss and limb ataxia

Intracranial angiolipomas are rare entities and are infrequently symptomatic. These benign lesions are adherent to the surrounding neurovascular structures as they share the same blood supply, which limits their resectability, and impose a possibility of persistence of symptoms. However, due to recent advancements in the neuro-radiological fields and microneurosurgical techniques it has been possible to localise precisely and excise these lesions with low morbidity and mortality. The authors present an interesting rare case of intracranial angiolipoma of the right inferior colliculus situated in the quadrigeminal plate cistern. The patient had presented with ipsilateral hearing loss and upper limb ataxia. Interesting clinical findings, neuro-imaging studies and peroperative features are presented and discussed along with a brief review of the literature.