Hyperbaric oxygen pretreatment according to the gas micronuclei denucleation hypothesis reduces neurologic deficit in decompression sickness in rats.

During sudden or too rapid decompression, gas is released within supersaturated tissues in the form of bubbles, the cause of decompression sickness. It is widely accepted that these bubbles originate in the tissue from preexisting gas micronuclei. Pretreatment with hyperbaric oxygen (HBO) has been hypothesized to shrink the gas micronuclei, thus reducing the number of emerging bubbles. The effectiveness of a new HBO pretreatment protocol on neurologic outcome was studied in rats. This protocol was found to carry the least danger of oxygen toxicity. Somatosensory evoked potentials (SSEPs) were chosen to serve as a measure of neurologic damage. SSEPs in rats given HBO pretreatment before a dive were compared with SSEPs from rats not given HBO pretreatment and SSEPs from non-dived rats. The incidence of abnormal SSEPs in the animals subjected to decompression without pretreatment (1,013 kPa for 32 min followed by decompression) was 78%. In the pretreatment group (HBO at 304 kPa for 20 min followed by exposure to 1,013 kPa for 33 min and decompression) this was significantly reduced to 44%. These results call for further study of the pretreatment protocol in higher animals.

Therapeutic efficacy of right prefrontal slow repetitive transcranial magnetic stimulation in major depression: a double-blind controlled study.

BACKGROUND: Transcranial magnetic stimulation (TMS), a noninvasive technique for stimulation of the brain, has recently been suggested to be effective for the treatment of major depression. We conducted a double-blind, placebo-controlled study to assess the efficacy of slow repetitive TMS (rTMS) in patients with major depression. METHODS: Seventy patients with major depression (53 women, 17 men; mean age, 58.7 years; SD, 17.2 years) were randomly assigned to receive rTMS or sham rTMS in a double-blind design. Treatment was administered in 10 daily sessions during a 2-week period. Severity of depression was blindly assessed before, during, and after completion of the treatment protocol. RESULTS: All patients completed the first week of treatment and 67 completed the entire protocol. Patients who received rTMS had a significantly greater improvement in depression scores compared with those who received sham treatment. At the end of 2 weeks, 17 of 35 patients in the rTMS group, but only 8 of 32 in the sham-treated group, had an improvement of greater than 50% in their depression ratings. CONCLUSIONS: This controlled study provides evidence for the short-term efficacy of slow rTMS in patients with recurrent major depression. Additional studies will be necessary to assess the efficacy of rTMS as compared with electroconvulsive therapy as well as the long-term outcome of this treatment in major depression and possibly other psychiatric disorders.

Right prefrontal slow repetitive transcranial magnetic stimulation in schizophrenia: a double-blind sham-controlled pilot study.

BACKGROUND: The aim of this study was to extend our previous work on the therapeutic efficacy of repetitive transcranial magnetic stimulation (rTMS) in major depression to patients with schizophrenia. METHODS: Thirty-five inpatients with schizophrenia were randomly assigned to either right prefrontal rTMS or sham treatment and were rated before and after treatment for positive, negative, and depressive symptoms. RESULTS: Thirty-one subjects (rTMS = 16, sham = 15) completed a 2-week treatment protocol. No serious adverse effects were reported; however, rTMS was not superior to sham treatment on any of the clinical ratings. CONCLUSIONS: In contrast to our previous positive findings in major depression, right prefrontal slow rTMS does not appear to have a beneficial effect for actively psychotic patients with schizophrenia.

Pseudostereoscopic illusion caused by interhemispheric temporal disparity: clinical and experimental observations.

An extension of Pulfrich's pseudostereoscopic illusion to a situation without interocular disparity, ie, even under purely monocular circumstances, was clinically observed and experimentally produced. The perceived distortion of the movement of a swinging pendulum was found to depend on different combinations of interhemispheric disparity induced by selective prolongation of the conduction time from the nasal or temporal retina to the corresponding hemisphere. In patients, tumor pressure caused the slower conduction time. In normal subjects, neutral density filters covering different visual fields produced similar conduction delays under experimental conditions. Recording the visually evoked response from over each hemisphere provided an objective tool for demonstration and measurement of interhemispheric differences of retinocortical conduction times in various clinical and experimental setups.

Midbrain corectopia.

Intermittent corectopia was recently observed in a patient with bilateral, rostral midbrain infarction. Results from neuropathologic examination disclosed isolated but intact Edinger-Westphal nuclei. An explanation of midbrain corectopia centered on segmental innervation of the pupil by the Edinger-Westphal nucleus. In the presence of a paralyzed dilator muscle, select, central inhibition of sphincter tone resulted in an oval and eccentric pupil.

Malignant evolution of childhood chiasmal pilocytic astrocytoma.

A 27-year-old obese mentally retarded woman showed progression of antisocial behavior with periodic somnolence 18 years after biopsy and irradiation of a large pilocytic astrocytoma of the chiasm and adjacent structures. Visual function, although impaired, had not changed during the long period of postoperative observation. Before she died, the tumor showed angiographic and histologic features of malignant glioma, but neuroradiologic and neuropathologic studies did not establish conclusively that it involved new areas of the brain. This report documents a rare case in which an irradiated childhood optic glioma underwent delayed malignant evolution.

SPECT quantitation of cobalt-57 bleomycin delivery to human brain tumors.

A newly developed and validated noninvasive quantitative SPECT method was used to measure the in vivo uptake of [57Co]bleomycin (Co-bleo) in 13 human brain tumors and the uptake of [99mTc]glucoheptonate (GH) in 23 brain tumors. Significant differences in tumor uptake were found. The tumor concentration over time, the tumor to blood radio at 30 min and the tumor cumulative concentration of radioactivity showed marked differences even between tumors with the same histology. Only a weak correlation was found between tumor concentration of Co-bleo and of GH. Therefore a simple imaging agent such as GH cannot, at the present time, serve as an indicator of individual tumor uptake and further experience with other agents is still necessary. Contrary to the generally held view, no correlation was found between the concentration of drug in the blood and its tumor concentration. It is suggested therefore that the level of a drug in the blood cannot be used as a criterion of the amount that will penetrate the tumor. Direct SPECT measurement of the concentration of the drug in the tumor itself should be performed. The bioavailability of a drug is critical in order for it to exert it tumoricidal effect. The results, showing marked differences in uptake between brain tumors, suggest that before chemotherapy is administered, uptake of the chemotherapeutic drug in the individual tumor to be treated should be assessed and comparisons should be made between the uptake of a series of drugs to determine which drug would be most efficacious on the basis of its uptake as well as its tumor cell killing potential.

Quantitative bone scintigraphy using SPECT.

A quantitative single photon emission computed tomography (SPECT) technique for measuring radiopharmaceutical uptake in humans has been applied to bone scintigraphy. The method was validated by comparing SPECT measured percent of injected [99mTc]MDP in 16 normal skulls with well counter measurements of samples of the same bones obtained at surgery. A very good correlation (r = 0.96) was found. A very good interobserver correlation (r = 0.99) and agreement were also obtained when using quantitative bone scintigraphy (QBS). Control SPECT studies of uptake in the right and left iliac bones and the right and left sacroiliac regions in each patient showed no significant differences between the contralateral sides. Studies done in seven subjects at 2 and 4 hr after the same injection and in nine subjects 4 to 8 mo later in the same subjects showed a very good agreement and no significant differences between the two measurements were found. QBS is suggested as an accurate and reproducible index for assessment of the mass of remodeling bone. Preliminary results showed differences in QBS of normal subjects at different ages. A group of 68 young patients aged 18-26 yr showed a significant higher QBS (p less than 0.001) when compared to an older group of 62 patients aged 50-85 yr. There was, however, a wide range of uptake values for the same bone in the same group, suggesting that the method should best be used for following individual patients over time.

Visually evoked response. Use in neurologic evaluation of posttraumatic subjective visual complaints.

Evaluation of subjective visual complaints unassociated with objective signs is a frequent problem in neurologic and ophthalmic practice. The visually evoked response (VER) is an important tool for separating the functional from the organic in patients claiming visual disturbance. In visual complaints associated with late posttraumatic epileptic activity, the VER can demonstrate an abnormality even in asymptomatic intervals. In complaints due to concussion, it demonstrates disorganized evoked responses initially and later a return of the normal resonse. It shows an abnormality in the occipital lobes during and after transient compression of the vertebral artery. A normal VER excludes all but trivial involvement of the visual system, symptomatic claims of the patient notwithstanding.

Lithium at therapeutic concentrations inhibits human brain noradrenaline-sensitive cyclic AMP accumulation.

Lithium at a therapeutically effective concentration of 1 mM caused significant inhibition of the rise in cyclic AMP induced by noradrenaline in fresh surgically-obtained slices of human brain.

Dissociation of somatosensory and motor evoked potentials in non-comatose patients after head injury.

OBJECTIVES: This study was performed to evaluate the clinical value of combined use of somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) in patients with different brain lesions after head trauma. METHODS: A total of 64 patients with minor and moderate head injury were investigated by means of SEPs recorded over the parietal and frontal areas and MEPs following single-pulse transcranial magnetic stimulation (sTMS) and slow-rate repetitive transcranial magnetic stimulation (rTMS). RESULTS: In almost 50% of the patients, a dissociated impairment of somatosensory and motor evoked potentials was found. This dissociation was related to different distribution of SEP and MEP abnormalities in head injury subgroups. The higher threshold to sTMS and increased variability of the MEP amplitude during slow-rate rTMS were the most prominent features in patients with focal brain contusions, suggesting impairment of the cortical excitability. SEP abnormalities, as well as central conduction impairments, were more noticeable in patients with diffuse brain injury. CONCLUSIONS: A combined analysis of SEPs and MEPs may improve the assessment of cortical dysfunctions and central conduction abnormalities in non-comatose patients with head injury. A slow-rate rTMS may be considered as a complementary technique to the evaluation of the threshold in assessment of the excitability of the motor cortex in minor and moderate head injury.

Visual evoked potentials in experimental allergic encephalomyelitis.

We have compared the clinical signs, brain pathology and visually evoked responses (VEP) of guinea pigs with experimental allergic encephalomyelitis (EAE). Animals immunized with myelin basic protein had a milder disease, both from the clinical and histological points of views, compared to those immunized with crude white matter extract. However, VEP findings were quite similar in both groups. The VEP of the majority of animals from both groups showed changes before or at the same time that neurological signs appeared. Electrophysiological responses were usually characterized by abnormal wave shapes and prolonged latencies. Recovery of the VEP usually preceded the recovery from clinical signs. In contrast, the severity and incidence of brain tissue pathology was not correlated to either clinical signs or VEP changes. Possible explanations of the electrophysiological, clinical and histopathological changes and their time-course are discussed.

Leeches for the unfortunate locksmith: self-inflicted posttraumatic transient cerebral blindness--mode of treatment and underlying mechanism (1826).

In 1826, Jean-Pierre Gama, a French military surgeon, treated a young locksmith who had self-inflicted posttraumatic transient cortical blindness. This may be the earliest detailed, firsthand description of this condition by a medically and scientifically trained observer. Gama's report sheds light on the concept of the mechanism of coup-contrecoup of cerebral concussion and its treatment in the early 19th century and on the germinating discipline of cerebral localization.

Somatosensory evoked potential to peroneal nerve stimulation in patients with herniated lumbar discs.

The somatosensory evoked potential (SEP) to peroneal nerve stimulation was recorded from 76 patients with myelographically proven herniated lumbar disc and was compared with normative data obtained from 65 healthy subjects. All patients with disc herniation had an abnormal SEP even when examination failed to disclose sensory deficits. In the patients with distortion of a root sleeve, the SEP abnormality was confined to the involved side. When myelography demonstrated large defects in the dural sac, there was electrophysiological evidence of disturbed conduction from the asymptomatic leg also. SEP changes in postoperative examinations correlated well with improvement or worsening of the patient's condition and enabled objective evaluation of the dynamics of sensory conduction along the involved structures.

Transcranial Doppler in vertebrobasilar vasospasm after subarachnoid hemorrhage.

OBJECTIVE: The primary objective of this study was to assess the incidence of vertebrobasilar vasospasm after subarachnoid hemorrhage (SAH) by means of transcranial Doppler ultrasonography and to evaluate the clinical significance of this phenomenon. The secondary objective was to analyze the different factors influencing the development, the severity, and the duration of vertebrobasilar vasospasm. METHODS: Fifty-seven patients with traumatic SAH and 44 patients with spontaneous SAH were evaluated and monitored by means of transcranial Doppler ultrasonography. Vasospasm of the anterior and middle cerebral arteries was defined by mean flow velocities (FVs) exceeding 120 cm per second and at least three times the FV of the internal carotid artery. Vasospasm of the basilar and vertebral arteries was defined by a mean FV exceeding 60 cm per second. RESULTS: Vasospasm of the anterior or middle cerebral arteries was found in 27 patients and was associated with vertebrobasilar spasm in 20 patients. FVs in anterior circulation vessels were neither related to the cause of the SAH nor did they correlate with the outcome. Forty-six patients (45.5%) had FVs exceeding 60 cm per second and 25 (24.8%) had FVs exceeding 85 cm per second. In 10 of these patients, direct or computed tomographic angiography showed arterial narrowing involving the vertebrobasilar system, whereas in 21 more patients, computed tomography disclosed a cerebral infarction involving the vertebrobasilar vascular territory. Vertebral artery FVs in this group were twice that of the ipsilateral carotid artery. Vertebrobasilar vasospasm was significantly more frequent after head injury, although it was not related to the type of intracranial lesion or the Glasgow Coma Scale score at admission. It did correlate, however, with outcome (P < 0.0001) and with the intensity of SAH (P < 0.0001). Delayed neurological deterioration occurred in 14 patients and was significantly more frequent in patients with basilar artery FVs above 85 cm per second (P < 0.001). Prognosis, however, could not be reliably predicted by FVs in the basilar artery, even when an FV of 110 cm per second was chosen for prediction criterion. CONCLUSION: These results suggest that vertebrobasilar vasospasm is more common than previously thought, especially in association with head injury, with which it may significantly contribute to brain stem ischemic lesions and therefore justify specific therapeutic measures.

Diffuse axonal injury: analysis of 100 patients with radiological signs.

One hundred patients with head injuries who showed diffuse axonal injury on computed tomographic scans are reported. Evaluation of the Glasgow Coma Score, pupillary signs, and computed tomographic findings on admission led to an improved ability to forecast outcomes. Our relatively good results as compared with other series, can be explained by the high proportion of children and by the liberal use of computed tomography to evaluate head injuries, thus revealing that concussion may sometimes be regarded as an early form of diffuse axonal injury.

Reversible facial pain due to hydrocephalus with trigeminal somatosensory evoked response changes. Case report.

A patient with hydrocephalus due to aqueductal stenosis suffered facial pain which was relieved after the insertion of a ventriculoperitoneal shunt. The trigeminal somatosensory evoked response (TSER) of the affected side showed lower amplitudes and longer latencies as compared to the unaffected side. Following surgery, the waves regained higher amplitudes and shorter latencies. An episode of shunt malfunction was accompanied by recurrent facial pain and impairment of the TSER. Both improved after revision of the shunt. The possible etiology of facial pain in patients with hydrocephalus is discussed.

Sensory evoked response to electrical stimulation of the trigeminal nerve in humans.

Electrical stimulation of the upper and lower lips of normal subjects evoked a consistent response recorded from over the face area of the ipsi- and contralateral hemispheres. This response consisted of seven discrete waves. Peak latencies ranged from as early as 8 msec to 115 msec. Stimulation of the lower lip evoked a response of lower amplitude and reversed polarity, as compared to te upper lip stimulation response. The data support the validity of the trigeminal sensory evoked response in the evaluation of the trigeminal pathways. Previously reported methods are reviewed and compared.

Gradual resolution of an arachnoid cyst after spontaneous rupture into the subdural space. Case report.

The authors present the case of a young patient in whom the spontaneous rupture of a known, long-standing middle fossa arachnoid cyst into the subdural space was documented. This spontaneous rupture was followed by gradual diminution of the cyst to near-complete resolution.

Transient global amnesia associated with a single metastasis in the non-dominant hemisphere. Case report.

A patient in whom transient global amnesia (TGA) led to the diagnosis of a metastasis of a transition-cell carcinoma of the bladder to the non-dominant hemisphere is described. In previously reported cases of TGA associated with brain tumors, the tumors involved either the dominant or both hemispheres. The etiology of TGA associated with a brain tumor is most likely vascular, as suggested by the sudden development and the transitory character of the event. In contrast to the "common" form of TGA (where both temporal lobes suffer temporary ischemia), in these patients only one side of the limbic system is affected, because a brain tumor has already compromised the other limbic area. Therefore, the dominance of the hemisphere with the tumor is of no consequence, as both hemispheres have been involved. It is concluded that the TGA in these patients is not due to, but is rather associated with, a unilateral brain tumor.