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OBJECTIVE: Non-linear EEG analysis can provide information about the functioning of neural networks that cannot be obtained with linear analysis. The correlation dimension (D2) is considered to be a reflection of the complexity of the cortical dynamics underlying the EEG signal. The presence of non-linear dynamics can be determined by comparing the D2 calculated from original EEG data with the D2 from phase-randomized surrogate data. METHODS: In a prospective study, we used this method in order to investigate non-linear structure in the EEG of Alzheimer patients and controls. Twenty-four patients (mean age 75.6 years) with 'probable Alzheimer's disease' (NINCDS-ADRDA criteria) and 22 controls (mean age 70.3 years) were examined. D2 was calculated from original and surrogate data at 16 electrodes and in three conditions: with eyes open, eyes closed and during mental arithmetic. RESULTS: D2 was significantly lower in the Alzheimer patients compared to controls (P = 0.023). The difference between original and surrogate data was significant in both groups, implicating that non-linear dynamics play a role in the D2 value. Moreover, this difference between original and surrogate data was smaller in the patient group. D2 increased with activation, but not significantly more in controls than in patients. CONCLUSIONS: In conclusion, we found decreased dimensional complexity in the EEG of Alzheimer patients. This decrease seems to be attributable at least partially to different non-linear EEG dynamics. Because of this, non-linear EEG analysis could be a useful tool to increase our insight into brain dysfunction in Alzheimer's disease.

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To assess whether electrophysiological tests are of use in differentiating between patients with asymptomatic cervical stenosis and patients with clinical evidence of myelopathy, we studied motor evoked potentials (MEPs) to magnetic brain stimulation and somatosensory evoked potentials (SEPs) in patients with asymptomatic cervical cord compression and compared the results to healthy age-matched controls. The MEPs were normal in 23 of 25 patients and SEPs in 22 of 23 patients. Thus, MEPs and SEPs are normal in most cases of asymptomatic cervical stenosis. As previous studies have shown MEPs, and to a lesser extent SEPs, to be sensitive in the detection of spondylotic myelopathy, our data indicate that MEP and SEP may be clinically useful for differentiating patients with cervical stenosis who have myelopathy from those who have not.

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We present the MRI appearances of advanced degenerative changes at the atlanto-odontoid (AO) joint. Changes including obliteration of the joint space, subchondral sclerosis and osteophytosis were clearly depicted on fast gradient-echo T1-weighted MRI images. Recognition of these changes may be helpful in the diagnosis in patients with suboccipital pain.

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We discuss the relationship of atlanto-odontoid (AO) (anterior C1-C2 joint) osteoarthritis to suboccipital pain. A questionnaire regarding suboccipital neck pain was presented to 210 consecutive patients undergoing computed tomography (CT) of the brain or sinuses for a variety of indications. In all patients the AO joint and the lateral scout image of the cervical spine were studied. In 104 (49%) degenerative changes were seen at the AO joint. There were 89 patients (42%) who reported pain in the suboccipital region, although this was not the reason for CT in any patient. Statistical analysis of the prevalence of suboccipital neck pain in all patients showed the presence of AO osteoarthritis seen on CT to be associated with occurrence of these symptoms. This association remained significant in the same study population after excluding patients with a history of rheumatoid arthritis, migraine, stress and neck trauma and patients with signs of degenerative changes of C2-C7 on the computed lateral scout image.

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The craniocervical junction was assessed in 700 consecutive unselected patients undergoing CT of the brain or paranasal sinuses, to investigate whether transverse ligament calcification was associated with advanced degenerative changes at the anterior atlanto-odontoid (AO) joint. Calcific deposits within the transverse ligament were seen in 40 patients (5.7%). The prevalence of this condition increased with age. Advanced degenerative changes (marked osteophytes and obliteration of the joint space) at the anterior AO joint were significantly more frequent in patients with transverse ligament calcification than in age-matched controls. We conclude that transverse ligament calcification is seen frequently in the elderly and very frequently with advanced degenerative changes at the anterior AO joint.

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Out of 620 consecutive examinations of the atlanto-odontoid joint in patients referred for computed tomography (CT) of the brain or paranasal sinuses, gas collection within the atlanto-odontoid joint was observed in 12 (1.9%). Degenerative abnormalities at the atlanto-odontoid joint were significantly more frequent in patients with a gas-induced vacuum phenomenon than in an age-matched control group. The CT findings and association of the vacuum phenomenon with osteoarthritis of the atlanto-odontoid joint are discussed.

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Monomeric (iohexol 300 mg I/ml) and dimeric (iodixanol 270 mg I/ml) nonionic contrast media were compared in a double-blind, randomised, parallel group trial. Safety and efficacy of the media in intra-arterial cerebral digital subtraction angiography were evaluated by assessing adverse events, discomfort, EEG, heart rate and quality of radiodiagnostic information. Seventy-six patients underwent selective injection of the carotid and/or vertebral arteries. Both contrast media were well tolerated. No serious adverse events occurred. No effects on heart rate and EEG were evident. The arteriograms were of high quality and overall diagnostic information was optimal in 94% of the examinations. No clinically important differences between the two contrast media were found.

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STUDY DESIGN: In this prospective study, the authors evaluated the atlanto-odontoid (AO) joint in 500 consecutive patients who underwent computed tomographies (CTs) of the brain or paranasal sinuses. OBJECTIVES: The objective of the study was to determine age specificity of various morphologic abnormalities related to osteoarthritis at the AO joint in patients referred for CT primarily to exclude brain or sinus abnormalities. SUMMARY OF BACKGROUND DATA: In all patients, at least two axial slices through the AO joint were evaluated by two authors, and agreement was reached by consensus. METHODS: Abnormal morphology was categorized into three groups: (1) osteophytosis; (2) obliteration of the joint space; and (3) transverse ligament calcification. RESULTS: In a significant percentage of older individuals, some form of degenerative disease is present. These changes show a roughly linear progression with advancing age. CONCLUSION: Morphologic changes related to AO osteoarthritis are frequent coincidental findings in patients referred for CT examination of the brain or paranasal sinuses. Awareness of the appearance and prevalence of degenerative changes in the AO joint on CT is important because reports in the literature and earlier findings of the authors indicate that these changes can be a source of suboccipital headache.

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The purpose of this study was to assess the accuracy of lateral cervical spine radiography in the detection of degenerative atlantoodontoid (AO) osteoarthritis, with CT as gold standard. In 50 patients, lateral radiographs and CT of the AO joint were blindly and independently graded by two radiologists: 0 = normal, 1 = mild degenerative disease, 2 = severe degenerative disease. Radiography was most accurate in distinguishing absent or mild disease from severe disease (83% sensitivity, 84% specificity). Sensitivity in distinguishing absent disease from mild or severe disease was 87%. Specificity, however, was low (52%), due to overestimation of the degenerative involvement on radiography. It is concluded that conventional radiography is a useful technique in screening for AO osteoarthritis, especially in severely degenerated joints. However, CT provides the best radiographic detail necessary for accurate diagnosis.

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The clinical course, transcranial Doppler ultrasound (TCD) findings, and angiographic outcome are reported for a patient with a traumatic carotid artery dissection. Transient asymmetrical decreased middle cerebral artery blood flow velocities led to the suspicion of an internal carotid artery (ICA) stenosis. Duplex scanning and angiography subsequently demonstrated an extracranial traumatic ICA dissection in combination with a traumatic saccular aneurysm. These data imply that TCD monitoring has a potential to diagnose not only well established complications of neurotrauma, such as vasospasm and intracranial hypertension, but may also suggest the presence of traumatic extracranial carotid obstructions.

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A 43-year-old woman underwent subtotal removal of a cervical spinal leiomyoma in 1980 and 1981. When her (cyclic) symptoms recurred and tumor growth was demonstrated, she was treated with a synthetic anti-gonadotropic hormone (Danazol; Danatrol) until menopause, when medication could be discontinued without further recurrence of her symptoms or increase in size of the residual tumor.

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Motor evoked potentials (MEPs) were studied in 28 patients with cervical spondylotic myelopathy. MEPs after cortical stimulation were abnormal in 27 patients, the responses in the leg muscles being affected the most often. Clinically asymptomatic motor lesions were detected in 7 patients (25%). The central motor conduction time (CMCT) for the abductor digiti minimi muscles correlated significantly with the clinical disability, whereas the radiological findings did not correlate with the clinical and neurophysiological parameters. In 9 patients MEPs were also recorded in the biceps muscles. The 7 patients with an abnormal CMCT for the biceps muscles had the most severe stenosis at the C-4-C-5 level or higher. The 2 patients with normal MEPs of the biceps muscles both had a stenosis at the C-5-C-6 level. The results of this study suggest that MEPs are useful for detecting spinal cord dysfunction and for localizing the level of the lesion. Some recommendations regarding the possible use of MEPs in the clinical evaluation of patients with cervical spondylotic myelopathy are given.

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In a consecutive series of 100 patients with blunt head trauma the efficacy of routine skull and cervical radiography was studied. Neurocranial and facial skeletal lesions were present in 8 patients, only 1 skull fracture being completely unsuspected clinically. In all 79 patients without cervical signs or symptoms the cervical spine films were within normal limits. Only two of the 21 patients with some form of local cervical spine symptomatology presented with traumatic changes. In 19 patients the cervical spine films did not demonstrate the cervicothoracic junction to satisfaction. Although this study confirms the low yield of routine conventional radiography in patients with blunt head trauma, the authors state that optimal conventional examination of the cervical spine is mandatory in all patients with blunt head trauma and the slightest suspicion of cervical symptoms or complaints and in those patients in whom either clinical examination or the clinical history is not completely satisfactory. The cervicothoracic junction should be adequately visualised. A CT or MRI scan of the brain should be preferred over conventional skull films in those patients in whom examination of the skull is considered indicated.

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The case histories of two patients with an acute spinal epidural abscess are reported. When presented with a patient suffering from a spinal cord syndrome, the physician must keep in mind the possibility of a spinal epidural abscess. A rapid diagnostic procedure, prompt laminectomy, and medical treatment are particularly essential to total recovery in such cases.

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A patient with a mobile schwannoma of the cauda equina is described. There was considerable discrepancy between the localization of the tumor at myelography and the findings at both initial surgery and repeat myelography, confirmed by definitive surgery. Such mobility is rare, but should be kept in mind when surgery is performed for a tumor of the cauda equina.

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Some of the patients with homonymous hemianopia are unaware of any visual defect, whereas others perceive this defect more of less consciously. Analysis of the CT scans of 41 cases showed that patients who are partially or fully aware of the hemianopia have purely occipital lesions. The patients who were not aware of the visual defect were found to have larger and more anteriorly situated lesions. Parietal lesions or lesions interrupting the associative pathways to the primary or secondary visual association cortex are considered to be responsible for the lack of awareness of the defect.

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In a case of bilateral horizontal gaze paralysis, vertical gaze was clinically intact but eye movement recordings demonstrated a transient reduction of vertical saccadic velocities. Horizontal caloric vestibulo-ocular responses were absent. CT scanning and NMR imaging showed a hematoma in the median pontine tegmentum. This case provides additional evidence that vertical and horizontal saccade genesis may be independent of caudal paramedian pontine reticular formation lesions.

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