Magnetic resonance imagings (MRI) showed the nodular lesion of the third ventricle to be hyper intense, without enhancement, in weighted spin-echo sequences, and mainly hypo intense in-weighted spin-echo sequences.

External ventricular drainage resulted in clinical and radio logic improvement. The cyst was evacuated by endoscopy, and pathologic examination revealed colloid cyst material.

A 58-year-old woman presented with cognitive deterioration, memory loss and apathy of approximately 3 months’ duration. Her history was unremarkable. Neurologic examination revealed temporal — spatial disorientation, mental slowness, memory alteration, right crural paresis and hyperreflexia in the left leg.

A cranial CT examination showed a homogeneous nodular lesion localized in the third ventricle, with minimal peripheral contrast uptake, as well as biventricular hydrocephalus and left atrial diverticula. MRI scanning revealed a nodular lesion in the anterior third of the third ventricle, which was hyper intense on weighted spinecho sequences and had areas of hypo intense signal on weighted spin-echo sequences, as well as active biventricular hydrocephalus and left atrial diverticula. The patient underwent surgery for excision of the lesion. Pathologic examination revealed a colloid cyst.

Massive ventricular dilatation causes stretching and dehiscence of the fornix with formation of unilateral or bilateral pial pulsion diverticula of the inferomedial wall of the atrium. Such dilatation may result from a partial defect in the ipsilateral tentorial band, which leads to herniation of the wall. Enlargement of the pial pouch creates a dramatic subarachnoid cyst, which may herniate downward through the incisura into the supracerebellar and quadrigeminal cistern.

These atrial diverticula can compress the mesencephalic tectum and can be mistaken for an arachnoid cyst or an ependymal cyst(f.1,3) of the quadrigeminal cistern. It is important to recognize these cysts and distinguish them from atrial diverticula, since these cysts can cause hydrocephalus, which should be treated with a direct intracystic shunt or excised. In contrast, atrial diverticula generally improve or disappear with suitable drainage of the hydrocephalus. This indicates that, although atrial diverticula are favoured by the defect in the tentorial band, they are secondary to severe, chronic hydrocephalus.

The CT and MRI images showed clearly the herniation of the atrial wall, tentorial hypoplasia and, on occasion, lateral displacement of the internal cerebral veins. They also demonstrated the possible mass effect on the area of the quadrigeminal platform and vermian cistern.

Bilateral diverticula can be seen in cases with shortening of both tentorial bands. The formation of atrial diverticula has been described in severe hydrocephalus secondary to brain stem gliomas, hypothalamic gliomas, third ventricular epidermoidomas and other tumours. Other nontumoral causes include granular ependymitis, aqueductal gliosis, external hydrocephalus and atresia of the foramen of Monro.

Colloid cysts of the third ventricle are rare, benign, congenital cystic neoplasms. They account for 0.25% to 0.5% of all intracranial cysts. Although the most widely accepted theory is that they originate in the primitive neuroepithelium of the tela choroidea they present non-neuronal traces of olfactory mucosa, and for this reason the term ”neuroepithelial cyst” is not exact.

Their location in the anterior part of the third ventricle can obstruct the foramina of Monro and create acute or chronic hydrocephalus, which can become severe. Colloid cysts are usually biventricular and symmetrical, but can be unilateral.

See also:  Zenker’s Diverticulitis and Diverticulitis Causes

Perforated sigmoid diverticulitis and their abscesses often resolve spontaneously. However, large or unresolving abscesses may require percutaneous drainage under ultrasound or CT guidance. Perforation of a diverticular abscess into the peritoneal cavity will result in purulent peritonitis with localized tenderness becoming generalised peritonism.

The localized inflammatory process associated with a diverticulum may perforate through another epithelial surface to form a fistula. The commonest type of fistula associated with diverticular disease is a colovesical fistula resulting from perforation of a diverticulum into the bladder. Patients with colovesical fistulae may present without bowel symptoms but with recurrent urinary tract infections and/or pneumaturia.

Fistulation can occur into other organs, such as the vagina or small intestine, and occasionally enterocutaneous fistulae may occur.

Generalized peritonitis associated with diverticular disease is due to the presence of free pus, faeces, or both, within the peritoneal cavity. Faecal peritonitis occurs where there has been necrosis of the intestinal wall resulting in the leakage of faeces into the peritoneal cavity. Patients are often gravely ill with marked peritonism and septic shock.

Bleeding sometimes occurs from vessels at the neck of a diverticulum and tends to be profuse – such blood loss usually arises from a single diverticulum, most frequently situated in the right colon.

Diverticular disease cannot be held responsible for occult lower gastrointestinal bleeding leading to an iron deficiency anaemia; in these situations other causes should be sought, such as neoplasia or angiodysplasia.

Inflammatory changes with associated scarring from previous episodes of acute diverticulitis and smooth muscle hypertrophy may be sufficient to cause a complete blockage of the colonic lumen and precipitate acute large bowel obstruction. Incomplete obstruction resulting from scarring may result in a variable bowel habit and intermittent colicky abdominal pain. Stricturing as a result of diverticular disease can be indistinguishable from malignancy on radiological investigation.

Diverticulosis is detected readily by both barium enema and contrast enhanced computed tomography (CT). Double contrast barium enema will demonstrate diverticulae, any strictures present and may also be helpful in demonstrating the presence of fistulae.

In areas of severe diverticulosis it may be impossible to safely exclude small polyps or carcinomas, and a colonoscopy or flexible sigmoidoscopy is indicated if doubt exists. Double contrast barium enema is deferred in the presence of acute diverticulitis and is usually performed 4-6 weeks after the acute episode has settled.

In acute situations other imaging modalities such as CT and/or ultrasound scanning provide the mainstay of investigation.

Colonoscopy is easily performed as an outpatient procedure. It clearly demonstrates the presence of diverticulae and any other mucosal abnormalities. It is the procedure of choice when patients present with rectal bleeding or where a barium enema has failed to adequately delineate an area of the colon. Colonoscopy, however, may be difficult in the presence of extensive diverticular disease due to spasm, rigidity and the presence of the diverticulae themselves.

Computerised tomography and ultrasound scanning Contrast enhanced CT scanning is the investigation of choice in patients with acute diverticultis when the characteristic colonic wall thickening with inflammation of pericolic fat are frequently seen. In complicated cases, abscesses, extraluminal gas and extraluminal contrast may all be detected by CT scanning. Drainage of intra- abdominal abscesses under CT guidance is practiced in many units and can prevent the need for operative intervention in the acute setting. Ultrasound scanning, although less sensitive, can also demonstrate wall thickening and the presence of significant abscesses.