P. Macpherson

BRAIN LESIONS DETECTED BY MAGNETIC RESONANCE IMAGING IN MILD AND SEVERE HEAD INJURIES

50 patients were studied by magnetic resonance imaging (MRI) within one week of a head injury. Abnormalities indicating primary brain damage were found in 46 patients, almost twice as many as with computed tomography. Cortical contusions were the most common finding, irrespective of the effect of injury on the level of consciousness. Intracerebral lesions were seen only in patients who had lost consciousness and were present in 29 of 42 patients whose consciousness was still impaired on arrival at hospital. Lesions in the deep white-matter of the cerebral hemispheres were seen in 15 patients; they were significantly more frequent in patients in coma but were also seen in patients who had lost consciousness for no more than 5 min. The findings indicate that lesions in the cerebral hemispheres may be the primary factor in traumatic unconsciousness. MRI studies may also clarify the sequelae of head injuries.

Magnetic resonance imaging in acute head injury

Using cardiorespiratory monitoring and support equipment compatible with a low field (0.15 T) system, magnetic resonance imaging (MRI) of patients suffering acute head injuries proved to be both feasible and safe. An abnormality was demonstrated by magnetic resonance imaging in 46 of 50 patients examined within 7 days of head injury using T2 weighted (SE2200/80) and T1 weighted (IR2000/600/40) multislice sequences. IN contrast, computed tomography (CT) demonstrated abnormalities in only 31 of the 50 patients. Intracranial extracerebral space-occupying collections of blood were well shown by magnetic resonance imaging which provided especially clear definition in the posterior fossa, subtemporal and subfrontal regions. Magnetic resonance imaging was more sensitive to cerebral abnormalities associated with traumatic unconsciousness and detected parenchymal lesions both in patients in coma and in those who had lost consciousness for only a few minutes. Lesions seen with MRI but not with CT included non-haemorrhagic contusions and abnormalities thought to reflect shearing injuries of white matter and intracerebral vessels. Magnetic resonance imaging is an effective alternative to CT; the additional information it can provide should be valuable in increasing the understanding of the early effects and late consequences of a head injury.

The value of pre-operative embolisation of meningioma estimated subjectively and objectively

SummaryIn a personal series a comparison has been made of the subjective and objective assessments of benefit between a group of patients in whom preoperative embolisation for meningioma was performed and a group, referred during the same timescale, in whom embolisation was either not possible or not appropriate. Preoperative difficulty with bleeding was experienced in 25% of the embolisation group and in 62% of the non-embolised group. Blood replacement overall was less in the embolised patients. Surgical complications occurred in 21% of those embolised but in 54% of those in whom embolisation had not been performed. At follow-up the outcome was rated as good in 79% in the embolisation group as opposed to 58% in the non-embolised group. Preoperative embolisation was therefore beneficial.

A quantitative index of ventricular and extraventricular intracranial CSF volumes using MR imaging.

A new technique is described that utilises a novel magnetic resonance pulse sequence to produce a quantitative index both for ventricular and, for the first time, extraventricular intracranial CSF volumes. The pulse sequence is a combination of a null-point inversion recovery sequence with an extended spin-echo read (echo time = 400 ms), which produces a contrast of CSF to white or grey matter of approximately 120:1. A series of experiments are performed on phantoms representing CSF filled ventricles and sulci over a wide range of volume values, and it is found that the standard deviation of differences between true and estimated values is 3.9% for ventricles, 4.6% for total cranial CSF, and 7.9% for CSF within the sulci. Normal volunteer reproducibility studies revealed corresponding standard deviations of less than 5.5%. Using the technique to produce absolute estimates of CSF volumes in normal subjects and patients produced results in good agreement with previously published necropsy studies. The technique has wide neurological and neurosurgical applicability particularly in terms of differential diagnosis and as an objective monitor of therapy or progression in conditions such as hydrocephalus, atrophy, and benign intracranial hypertension.

Pituitary microadenomas. Does Gadolinium enhance their demonstration

SummaryTen patients with biochemical evidence of a hormonally active pituitary adenoma were examined by dynamic contrast enhanced computed tomography (CT) and then by pre and post Gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging (MRI). Excluding one false positive case, CT and unenhanced MRI were comparable in the detection of microadenoma. Post Gd-DTPA examination gave more clear evidence of the actual adenoma in two patients and aided in the demonstration of a third. However, in two others all imaging techniques failed to demonstrate the microadenoma subsequently found at surgery. On the post enhancement MRI it was easier to assess the relationship of a tumour to the cavernous sinus and to visualise the relationships of the parasellar carotid arteries.

Gadolinium DTPA enhanced magnetic resonance imaging in acute head injury

SummaryWe studied the effect of contrast enhancement on magnetic resonance imaging (Gadolinium DTPA Magnetic Resonance) in 10 patients with a recent head injury. The use of contrast did not increase the number of traumatic lesions identified and we did not detect evidence of altered blood brain barrier permeability in any of the 7 patients, who had a total of 27 lesions, imaged between one and 4 days after injury. Enhancement was found in each of 3 patients imaged 6 or more days after injury. These findings suggest that traumatic cortical and intraparenchymal lesions are not associated with increased cerebrovascular permeability within the first 96 hours of a head injury.

Computed tomography of intracranial lymphoma

The appearances on computed tomography (CT) of 17 patients with histologically proven intracranial lymphoma have been analysed and abnormalities detected in 16. Four of the patients had systemic lymphoma. Multiple lesions were seen in eight patients (47%), in six of whom the multiple lesions in each patient were of similar appearance. There was good macroscopic correlation between the CT and post-mortem appearances in the eight patients who subsequently died, although in five, histological examination showed more extensive infiltration. Meningeal involvement was seen more commonly in the cases of systemic lymphoma than in the purely cerebral lymphomas, but parenchymal lesions were equally common in both. Grey matter lesions tended to be clearly demarcated, of increased density with little oedema or displacement; homogeneous density enhancement was produced by the intravenous injection of contrast medium. White matter lesions were usually poorly demarcated, of variable density with marked oedema and displacement, and with heterogeneous enhancement.

CT demonstration of a 5th ventricle ― a finding to KO boxers?

SummaryThe reported prevalence of 5th ventricles based on air studies varies from 1–12% and ranges up to 60% as an autopsy finding. The prevalence of what is usually an incidental anomaly has not been determined by computed tomography (CT). 5th ventricles are however known to be more common in brain damaged boxers and with the introduction of compulsory CT scanning for certain boxers it is necessary to know what significance to attach to the finding of a cavum in these individuals. To ascertain the prevalence and morphology of 5th ventricles as detected by CT in the population, a thousand consecutive scans were analysed for the presence or absence of a 5th ventricle and other associated midline developmental abnormalities and correlations made with any pathology found. A 5th ventricle was present in 5.5% of the group and in most cases was less than 3 mm wide. An apparent association with other pathology was found only in patients under the age of 15. A 6th ventricle was found in 0.5% while a cavum velum interpositum was present in 9.5%. The isolated finding of a small 5th ventricle on the CT scan of a young active boxer almost certainly represents a persistent congenital anomaly of no significance.

High-resolution computed tomography in pituitary microadenoma: Is seeing believing?

Controversy surrounds the reliability of high-resolution computed tomography (CT) in the identification of functioning microadenomas, especially in patients with hyperprolactinaemia and hypercortisolaemia. We studied 34 such patients: each underwent a high-resolution CT examination of the pituitary gland and each had a trans-sphenoidal exploration. Computed tomography showed 28 focal abnormalities but only 20 of these were confirmed to be due to a tumour at operation. In the other eight the tissue at the site of the radiological abnormality was normal histologically. In a total of 29 patients a tumour was found at operation and confirmed histologically; 20 were at the site of an abnormality shown by CT but in nine a tumour was found in a part of the gland judged to be normal radiologically. In general, good correlation between CT and the surgical findings was found only with tumours more than 6 mm in size. Of the indirect signs of a tumour, such as stalk deviation and a convex upper surface of the gland, only the former showed any correlation with the presence of a tumour. The results show that cautious, even sceptical interpretation of pituitary CT scans is essential and suggest that this investigation is not sufficiently reliable to be used as a routine in the assessment of hyperprolactinaemia or Cushings syndrome. Computed tomography should be reserved for patients undergoing pituitary surgery, those with an enlarged fossa on plain radiography and those with extreme hormone hypersecretion.

Radiculography: Is Routine Bed Rest Really Necessary ?

After undergoing metrizamide radiculography, 119 patients were randomly allocated to two groups, one group remaining ambulant and the other being kept in bed for 24 h. A member of staff who did not know the category allocation questioned each patient regarding the occurrence of side-effects 24 and 48 h after the procedure. It was found that the incidence and severity of complications was neither increased nor decreased by allowing the patient to remain ambulant.