The management of cerebellar abscess since the introduction of CT scanning

Sixteen patients with surgical infection of the posterior fossa are presented. There were 14 patients with cerebellar abscess, one patient with a solitary posterior fossa subdural empyema, and another with a combined cerebellar abscess and subdural empyema. Two of the cerebellar abscess patients also had supratentorial infections. The presenting features, aetiology, radiology and bacteriology are discussed with particular reference to differences in abscess re-accumulation, and outcome between those managed by aspiration and excision. We have been unable to show that either method of treatment is superior to the other. An overall mortality rate of 19% was achieved; however, for those with parenchymal cerebellar abscesses this was reduced to 13%. We conclude that burr hole aspiration with regular CT is a satisfactory method of treatment for cerebellar abscess.

Acute fatal parainfectious cerebellar swelling in two children. A rare or an overlooked situation?

We report 2 previously healthy children who developed sudden unexpected respiratory arrest and brain death, during a presumed Epstein-Barr meningitis in one case and a multisystemic infection of unknown etiology in the other. Diffuse swelling of the cerebellum with upward transtentorial and downward tonsillar herniation, shown by brain CT-scan and MRI obtained after the acute event, was the most probable cause of death. Review of CT images performed before or at the onset of deterioration already showed discrete signs of early upward herniation of the cerebellar vermis that were initially overlooked. At autopsy in the first case, an acute lymphomonocytic meningoencephalitis with predominant involvement of the cerebellum was observed. Few similar cases were found in the literature, indicating that acute cerebellar swelling is either a very rare or an unrecognized, possibly preventable cause of death in acute inflammatory or non-inflammatory encephalopathies in children.

Secondary changes in cerebellar perfusion (diaschisis) in hemiplegia during childhood: SPECT study of 55 children

Diaschisis is a functional impairment at a site in the brain remote from the lesion causing it. An investigation of cerebellar diaschisis in childhood was undertaken to better understand the functional maturation of the corticopontocerebellar tract in developing brain. A retrospective study of cerebellar diaschisis in 55 hemiplegic children was conducted using single-photon emission computed tomography (SPECT) with 123I-IMP. Cerebellar diaschisis was evaluated by 2 authors. Crossed cerebellar diaschisis (CCD) was found in 6 of 55 patients. SPECT findings of patients who presented with CCD disclosed supratentorial hypoperfusion of varying degrees, from focally to the whole hemisphere; however, patients had frontal and/or parietal hypoperfusion in common. A second type of cerebellar diaschisis also was demonstrated. Cerebellar hypoperfusion ipsilateral to supratentorial lesions, ipsilateral cerebellar diaschisis (ICD), was observed in 10 of 55 patients. CCD occurred in the patients who suffered from brain injuries after 7 years, 5 months of age, while ICD manifested in patients whose brain injuries occurred before 3 years, 1 month of age. The production of remote effects, such as CCD and ICD, could be closely related to maturation of the corticopontocerebellar tract in the developing brain during childhood.

[Acetazolamide effect on vascular response in crossed cerebellar diaschisis as measured by 99mTc-HMPAO SPECT]

We studied the effect of acetazolamine (DIAMOXR) on vascular response in areas with crossed cerebellar diaschisis (CCD) using consecutive 99mTc-hexamethyl-propyleneamine oxime (HMPAO) SPECT studies before and after DIAMOX administration with a subtraction method. Regions of interest were drawn over the bilateral cerebellar cortices and interhemispheric asymmetry indices (IAI) were obtained. Eleven of 14 patients with CCD at baseline showed decrease of IAI after DIAMOX administration. Although there is a possibility of underestimation of increase in perfusion in unaffected cerebellar hemisphere, this result suggests a greater increase in perfusion in the affected cerebellar hemisphere as compared with in the contralateral unaffected one and suggests more dilatation of the arterioles in areas with CCD post-DIAMOX than in areas without CCD. However nonsignificant correlation between IAI at baseline and difference of IAI from baseline to post-DIAMOX did not support the hypothesis of more dilatation post-DIAMOX of more constricted arterioles.

Monitoring therapeutic efficacy of decompressive craniotomy in space occupying cerebellar infarcts using brain-stem auditory evoked potentials

Brain-stem auditory evoked potentials (BAEPs) have been used to gauge effects of brain-stem dysfunction in humans and animal models. The purpose of this study was to evaluate the usefulness of BAEP in monitoring patients undergoing decompressive surgery of the posterior fossa for space occupying cerebellar infarcts. We report on serial BAEP recordings in 11 comatose patients with space occupying cerebellar infarcts undergoing decompressive craniotomy. BAEP studies were performed within 12 h after admission, 24 h following surgery and prior to extubation. BAEP signals were analyzed using latency determination and cross-correlation. Following surgery, 9 patients regained consciousness; 2 patients persisted in a comatose state and died subsequently. BAEP interpeak latency (IPL) I-V assessed prior to surgery exceeded normal values in all patients in whom it could be reliably measured (N = 9). Following decompressive surgery BAEP wave I-V IPL normalized in 5 patients, but remained prolonged despite dramatic clinical improvement in 4 patients. We prospectively computed the coefficient of cross-correlation (MCC) of combined ipsilateral BAEP trials after right and left ear stimulation. In all patients increasing MCC was associated with clinical improvement. Unchanging or decreasing MCC indicated poor outcome. We conclude that serial BAEP studies are an appropriate perioperative monitoring modality in patients with space occupying cerebellar infarcts undergoing decompressive surgery of the posterior fossa. Our study suggests advantages of cross-correlation analysis as an objective signal processing strategy; relevant information can be extracted even if BAEP wave discrimination is impossible due to severe brain-stem dysfunction.

Cerebellum and non-motor behaviour

This paper summarizes research work done on the non-motor and behavioural functions of the cerebellum. In 73 patients with bilateral cerebellar damage deficits in visuo-spatial organization for concrete tasks as well as in planning and programming of daily activities were found. Deficits in spatial learning were also observed in mutant mice with cerebellar damage. The studies suggest that the cerebellum is involved in cognition through the cerebello-frontal and cerebello-parietal loops.

Cranial computed tomography of elderly patients: an evaluation of its use in acute neurological presentations

We assessed the use of cranial computed tomography (CT) in elderly patients with acute neurological deficit and its influence on patient management. Clinical notes from 100 consecutive CT referrals from geriatric admissions presenting with acute neurological deficit were reviewed and categorized according to clinical presentation. CT results and subsequent therapy were recorded. Twenty of the patients had treatable lesions (in 6 out of 14 patients with signs atypical of stroke and 7 out of 19 patients with acute confusion). These two groups contained 68% of all treatable lesions found. Forty-four scans yielded no new diagnostic information; these included all scans for transient ischaemic attacks and for progression of stroke. The remaining scans yielded information regarding pathology but did not alter patient management. CT is a valuable first-line investigation in elderly patients presenting with signs atypical of stroke and unexplained confusion but may be less useful in patients with other presentations.

Reduced contralateral hemispheric flow measured by SPECT in cerebellar lesions: crossed cerebral diaschisis

Four patients with clinical signs of cerebellar stroke were studied twice by SPECT using 99mTc-HMPAO as a tracer for cerebral blood flow (CBF). When first scanned 6 to 22 days after onset, all had a region of very low CBF in the symptomatic cerebellar hemisphere, and a mild to moderate CBF reduction (average 10%) in contralateral hemispheric cortex. In all four cases clinical signs of unilateral cerebellar dysfunction were still present when rescanned 1 to 4 months later and the relative CBF decrease in the contralateral cortex of the forebrain also remained. The basal ganglia contralateral to the cerebellar lesion CBF showed variable alterations. A relative CBF decrease was seen in upper part of basal ganglia in all four cases, but it was not a constant phenomenon. A relative CBF increase in both early and late SPECT scans was seen at low levels of neostriatum in two cases. The remote CBF changes in cerebellar stroke seen in the forebrain are probably caused by reduced or abolished cerebellar output. The term "Crossed Cerebral Diaschisis" may be used to describe these CBF changes that would appear to reflect both decreased and increased neuronal activity.

Fastigial pressor response observed during an operation on a patient with cerebellar bleeding--an anatomical review and clinical significance

The fastigial pressor response (FPR) consists of an abrupt rise in blood pressure and tachycardia with hyperpneic response. The FPR is an important sign in posterior fossa surgery for respiration in postoperative patients. The authors experienced a distinct pressor, tachycardiac, and hyperpneic response elicited when controlling bleeding using a bipolar coagulator forceps at the subfastigial white matter in a 72-year-old man with cerebellar hemorrhage. This response was confirmed by bipolar electrodes, which produced a weak current under deeper anesthesia by increasing the concentration of enflurane. The postoperative course of this patient was uneventful. A FPR was suggested to be mediated by axons passing between the nucleus fastigii and the fourth ventricle. These commissural fibers mediating the FPR were suggested to be countercurrent efferent pathways from both sides of the nucleus parabrachialis lateralis, located at the dorsolateral corner of the rostral pons. The authors conclude that the partial destruction of the subfastigial commissural fiber bundle did not result in permanent respiratory deficit. Fatal respiratory disturbance might be anatomically suggested by completely cutting off this fiber bundle.

Probable cerebellar abnormality on 123I-IMP SPECT scans in epileptic patients with long-term high-dose phenytoin therapy. Based on observation of multiple cases

Quantitative assessment of regional cerebral blood flow (rCBF) in the bilateral cerebral and cerebellar cortices was performed in 13 epileptic patients receiving long-term high-dose phenytoin (PHT) therapy, using single photon emission computed tomography (SPECT) with N-isopropyl-(iodine 123) p-iodoamphetamine. In 4 of the 13 patients, both the cerebellar to frontal rCBF ratio and cerebellar to cerebral rCBF ratio showed low values as compared with those in 22 normal subjects matched for sex and age, probably reflecting abnormal relative cerebellar hypoperfusion. None of the 4 patients showed any abnormal findings on X-ray computed tomography or magnetic resonance brain imaging. The patients with a history of acute PHT intoxication tended to show the abnormal relative cerebellar hypoperfusion. These results suggest the utility of SPECT scans for early detection of cerebellar abnormalities known to be often present in epileptic patients, and imply a risk of long-term high-dose PHT therapy.

[A study of crossed cerebellar diaschisis on 123I-IMP SPECT images and its redistribution phenomenon]

Crossed cerebellar diaschisis (CCD) is interpreted as a functional deactivation, presumably caused by a loss of excitatory or inhibitory afferent inputs on the corticopontocerebellar pathway and others. A redistribution phenomenon (RD) is usually observed in the contralateral cerebellum with CCD on delayed images of 123I-IMP SPECT. This phenomenon was analyzed in a view point of rCBF measurement in 24 patients with brain tumor, infarction and so forth. Regional CBF was measured by the microsphere method with 123I-IMP and a delayed-to-early counts ratio (D/E ratio) was used. As a result, there was no relation between rCBF and the D/E ratio in the cerebellum, which means that RD is occurred by other factors except for rCBF in the cerebellum. Regional CBF and the D/E ratio in the contralateral and ipsilateral cerebellum was 46.3 ml/100 g/min, 1.01 and 57.0 ml/100 g/min, 0.86, respectively. These results mean that the high activity of IMP gradually decreased in the ipsilateral cerebellum, while, the low activity in the contralateral cerebellum was almost stable, and the difference of both activity reduced after 5 hours and RD was observed on the delayed image. The data indicate that retention mechanism of IMP and vascular permeability are not affected in the cerebellum with CCD.

Cerebellar diaschisis revisited: pontine hypometabolism and dentate sparing

A unilateral supratentorial lesion may cause hypometabolism in the contralateral cerebellar hemisphere (crossed cerebellar diaschisis). We analyzed glucose metabolism, measured by PET-FDG, in the posterior fossa in 67 patients (78 PET studies) with primary unilateral supratentorial brain tumors selected for visually obvious metabolic asymmetry in the cerebellar hemispheres. We found that glucose utilization was 17% lower in the contralateral cerebellar cortex (compared with the ipsilateral one), consistent with the selection criterion, and 19% lower in the ipsilateral pons, wherein lie the first order synapses of the corticopontocerebellar pathway. This finding helps to validate the prevalent view that cerebellar diaschisis is due to interruption of afferent input from the corticopontocerebellar pathway. However, glucose metabolism in the contralateral dentate nucleus was relatively preserved--only 2% less than the ipsilateral dentate. This "dentate sparing" suggests preservation of afferent input to the largest of the deep cerebellar nuclei from the Purkinje cells in the cortex, despite interruption of the major excitatory input to the Purkinje cells.

Crossed cerebello-cerebral diaschisis: a SPECT study

A scintigraphic single photon emission computed tomographic (SPECT) evaluation of frontal perfusion alteration was performed in five patients with known cerebellar lesions but with normal supratentorial computed tomographic (CT) or magnetic resonance (MR) scans. A clearly evident asymmetry was found in prefrontal areas in the four subjects with acquired cerebellar damage. The fifth subject, who had congenital left cerebellar hypoplasia, did not show any frontal flow asymmetry. The data support the growing clinical evidence that the cerebellum contributes to the cognitive processes of the frontal lobes and suggest a possible role for SPECT examination in the assessment of functional cognitive impairment in patients with acquired cerebellar lesions.

Massive cerebellar infarct complicated by hydrocephalus

We report a case of massive cerebellar infarction in which CT and MRI led to the diagnosis of acute hydrocephalus. All the neurological symptoms cleared after CSF shunting.

[The indication of surgical treatment of cerebellar hemorrhage]

61 patients with cerebellar hemorrhage were studied. The age at onset ranged from 15 to 84 years with a mean of 57.4 years. 49 cases were treated conservatively and 12 surgically and the mortality rates of the two groups were 32.5% and 25% respectively. Based on this study, it is suggested that the clinical and CT indications of surgical treatment of hematoma are as follows; Severe disturbance of consciousness; Bilateral eyeball fixation; Volume of hematoma over 10 ml; Size of hematoma over 4 cm in diameter; Marked acute obstructive hydrocephalus; Compression of cisterna ambieus and quadrigeminus.

Iniencephaly. A case report

Prenatal ultrasound diagnosed iniencephaly apertus at 21 weeks' gestation. In this rare central nervous system (CNS) malformation the brain and neck show the main pathologies. Retroflexion of the head with exaggerated cervicothoracic lordosis is always present, and CNS malformations in the form of anencephaly, spina bifida and encephalocele are often present. The ultrasonic diagnosis should be based on the finding of extreme dorsiflexion of the head accompanied by an abnormally short and deformed spine.

Reverse crossed cerebellar diaschisis in partial complex seizures related to herpes simplex encephalitis

Tc-99m HMPAO brain SPECT was performed in a patient who had partial complex seizures for 1 year after successful acyclovir treatment of biopsy-proven herpes simplex encephalitis 2 years earlier. In spite of antiepileptic medications, her seizures were intractable and occurred daily. Tc-99m HMPAO was administered intravenously while she was having subclinical seizures, and brain SPECT demonstrated an area of hyperperfusion in the right temporal lobe medially and in the contralateral cerebellum. This reverse of the crossed cerebellar diaschisis phenomenon in epileptic disorders has not previously been documented.

Treatment of cerebellar infarction by decompressive suboccipital craniectomy

BACKGROUND AND PURPOSE

We present an anecdotal series of 11 patients without past history of stroke with progressive neurological deterioration while on medical therapy for large cerebellar infarctions. Clinical signs of brain stem compression developed in these patients. Computerized tomography of the head confirmed mass effect from brain edema. It was the clinical judgment of the neurologists and neurosurgeons that each of these 11 patients would expire without surgical intervention.

METHODS

All 11 patients (seven men, four women; mean age, 54 years) were treated with suboccipital craniectomy for decompression and temporary ventriculostomy for cerebrospinal fluid pressure monitoring and drainage.

RESULTS

Seven patients demonstrated neurological improvement on the first postoperative day. Two patients returned to their previous jobs 3 months after surgery. The Barthel Index indicated that six individuals were functioning with minimal assistance within a follow-up period of 16-60 months. The remaining three were functionally dependent. No mortality was noted in this series.

CONCLUSIONS

These results suggest that decompressive suboccipital craniectomy may be an effective, lifesaving procedure for malignant cerebellar edema after a large infarction.

Acetazolamide effect on vascular response in areas with diaschisis as measured by Tc-99m HMPAO brain SPECT

The effects of acetazolamide (Diamox) on vascular response were investigated in areas with intrahemispheric thalamic diaschisis and crossed cerebellar diaschisis using consecutive Tc-99m HMPAO brain SPECT studies before and after Diamox administration. All six patients with thalamic diaschisis and five of eight patients with crossed cerebellar diaschisis at baseline showed significantly augmented perfusion after Diamox administration in the affected thalamus and cerebellum compared with that in the contralateral unaffected areas. These results suggest more dilatation of the arterioles in areas with diaschisis after Diamox administration than in areas without diaschisis. Diamox may produce relative luxury perfusion in areas with diaschisis.

Meningiomas, epidermoids, and other nonacoustic tumors of the cerebellopontine angle

Nonacoustic tumors of the CPA include meningioma, epidermoid, arachnoid cyst, lipoma, facial nerve schwannoma, and metastatic tumor, among others. Like AN, these lesions present with audiovestibular symptoms, facial nerve dysfunction, and other cranial nerve neuropathies. Preoperative differentiation among these lesions based on clinical history, physical examination, and audiovestibular testing is difficult. CT and gadolinium-enhanced MRI reveal the characteristic appearance of these tumors and make accurate diagnosis possible.

Cerebellar infarction in the young

BACKGROUND AND PURPOSE

Ischemic cerebrovascular disease in children and young adults usually affects the anterior circulation.

SUMMARY OF REPORT

We describe two cases of cerebellar infarction in the territory of vertebral artery supply, associated with physical exertion, in a young adult and in a child. Review of 31 previous cases of cerebellar infarction occurring in the first 2 decades of life demonstrated a mostly obscure causation; where a likely cause was found, trauma was most frequent. In 12 of the 31 patients, a vertebral artery (usually the left) was occluded. Patients were sometimes predisposed to such occlusions by subluxation between the first and second cervical vertebrae, allowing abnormal neck movements that can cause arterial injury and thromboembolism. Some of these cerebellar infarcts, like those of our patients, have followed physical exertion.

CONCLUSIONS

Cerebellar infarction can be life-threatening, but half of the patients, including ours, have had complete or near-complete recovery.

Crossed cerebellar diaschisis and crossed cerebellar atrophy: correlation of MR findings, clinical symptoms, and supratentorial diseases in 26 patients

Crossed cerebellar diaschisis is a condition in which cerebellar hypometabolism is ascribed to functional disconnection of the contralateral hemisphere from the cerebral cortex. Interruption of the cerebropontine-cerebellar pathway is thought to be the most likely mechanism of this remote transneuronal metabolic depression. This phenomenon can be diagnosed by positron emission tomography, as there is hypometabolism in the affected cerebellar hemisphere. The morphologic features of the affected cerebellar hemisphere in patients with the diagnosis of crossed cerebellar diaschisis have not previously been studied by MR imaging. We retrospectively reviewed 26 patients in whom the diagnosis of crossed cerebellar diaschisis was suggested by positron emission tomography; these patients also had MR studies. In all 26 patients, supratentorial diseases were documented by MR imaging. Twenty-four of the 26 patients had a pathologic diagnosis. Detailed clinical history was also obtained for all patients. MR findings of morphologic change in the affected cerebellum were correlated with the patient's clinical symptoms and supratentorial disease. Of the 26 patients, eight had cerebellar atrophy; the remaining 18 patients showed no MR abnormality of the affected cerebellum. In the 18 in whom no atrophy was seen on MR imaging, the majority of the supratentorial lesions were tumors. The eight patients in whom cerebellar atrophy was demonstrated usually had significant contralateral supratentorial hemispheric atrophy. The patients with atrophy were also generally younger (average age, 14 years) than the 18 patients without cerebellar atrophy (average age, 42 years). Our experience shows that a significant number of patients with crossed cerebellar diaschisis have morphologic changes of cerebellar atrophy shown by MR imaging. These patients usually have significant contralateral supratentorial hemispheric atrophy.

Crossed hemispheric diaschisis in unilateral cerebellar lesions

BACKGROUND AND PURPOSE

We studied 12 patients with unilateral cerebellar hemorrhage to look at its effect on regional cerebral blood flow.

METHODS

We used single-photon emission computed tomography by continuous inhalation of xenon-133. The blood flow was quantified in the cerebellum and in nine areas of interest on the slice passing through the basal ganglia.

RESULTS

The comparison of the blood flow values of the patients and control subjects showed a significant reduction in the contralateral hemisphere of the patients, predominantly in the frontal region and in the lenticular nucleus of the contralateral hemisphere but also in the anterointernal frontal area of the ipsilateral hemisphere. The analysis of the asymmetry indexes revealed in the same way significant differences between patients and control subjects in the frontal cortex and in the lenticular nucleus.

CONCLUSIONS

These results provided concordant evidence suggesting a blood flow reduction in the contralateral hemisphere. This phenomenon of "crossed hemispheric diaschisis" is probably related to the interruption of cerebellocortical tracts.