Static and dynamic responses of periodontal ligament mechanoreceptors and intradental mechanoreceptors.

1. The response properties of 39 periodontal ligament mechanoreceptors (PDLMs) and 12 intradental mechanoreceptors (IMs) related to the intact mandibular canine tooth were isolated by extracellular recording methods from the ipsilateral trigeminal semilunar ganglion. 2. The stimulus threshold and response magnitude of individual PDLMs depended on the direction of steady force applied to the intact canine tooth. Canine PDLMs as a population, however, did not have a preferred stimulus direction. IMs were activated only by a rapid mechanical transient applied to the intact tooth in any direction. The stimulus threshold and response magnitude of each IM were approximately equipotent in all stimulus directions. 3. Application of quantifiable ramp-and-hold stimulation showed that PDLMs can encode the intensity of steady forces as well as the rate of force ramps. Increasing the ramp rates decreased the total ramp discharge but increased the peak discharge frequency. IMs encoded only the rate of force ramps that were applied by percussion. Higher ramp rates increased both the total discharges and peak discharge frequency of IMs. 4. The dynamic response properties of PDLMs and IMs were clearly differentiated by sinusoidal vibratory stimulation. The maximum frequencies for entrainment of IM discharge at the stimulus cycle length (251 +/- 103 Hz, mean +/- SD) and at any periodicity including multiples of the stimulus cycle length (295 +/- 100 Hz) were significantly higher than the maximum frequencies for PDLM discharge entrainment at the stimulus cycle length (103 +/- 53 Hz) and at any periodicity (133 +/- 62 Hz). 5. The functional similarities of PDLMs and IMs, respectively, to slowly adapting type II mechanoreceptors and Pacinian corpuscle receptors in the skin are discussed. Our present findings, which complement earlier anatomic and behavioral evidence, strongly suggest that IMs subserve nonnociceptive and nonpain functions. Both PDLMs and IMs may provide a continuum of dynamic afferent inputs necessary for tactile sensibility of teeth.

[CT-guided stereotactic surgery of brain abscess].

Seven patients with brain abscess underwent CT-guided stereotactic aspiration using Iseki's stereotactic apparatus. Three of them were under the age of fifteen and four were older than thirty. The lesions were single and round in four cases, multilobular in two and multiple in one patient. Operations were performed after systemic administration of antibiotics for more than two weeks and after capsule formation was confirmed on CTs. Preoperative volume of the abscesses was estimated from CTs. The target point chosen was the center of the ring of the largest diameter in the enhanced lesion. Abscess was aspirated under monitoring with intraoperative CT scan. No continuous drainage was performed and no antibiotics were given directly into the abscess cavity. In all cases the center of the abscess was punctured with a single trial. Average volume of the preoperative brain abscesses was 18.8ml. Aspirated volume at the time of the operation averaged 16.9ml and all the abscesses decreased to unmeasurable size on CTs. In five of seven patients abscesses were cured after a single aspiration, and in one case after the second operation. One case required extirpation of the lesion. During the follow-up period of four months to five and a half years six patients showed no recurrence. One patient died of unrelated cause four and a half years after the operation. No operative complication was noted. There was no operative morbidity or mortality. Using a CT guided stereotactic method, brain abscess is punctured so accurately, regardless of its location and size, that damage to the surrounding brain during operation can be minimized. Therefore it is highly possible to aspirate abscesses completely.(ABSTRACT TRUNCATED AT 250 WORDS)

[MR imaging of traumatic cerebellar dysfunction].

Four cases of cerebellar dysfunction following head trauma are presented. Cerebellar signs revealed were those such as dysmetria, dysdiadochokinesis, horizontal nystagmus and ataxia. T2-weighted magnetic resonance (MR) imaging (0.15 tesla, spin-echo method; TR 2000 msec. and TE 100 msec.) revealed focal lesions in these patients, although CT scan failed to demonstrate any changes in the cerebellum. The cerebellar symptoms were maximal immediately after the trauma but improved gradually in two cases. These are compatible with the transient traumatic cerebellar dysfunction postulated by R. C. Cantu in 1969. The pathophysiology of this syndrome, whether it is due to cerebellar concussion or contusion, has not yet been determined. The abnormality of the cerebellum revealed by MR imaging seemed to be contusion rather than concussion. Therefore the authors presume that transient traumatic cerebellar dysfunction is caused by minor cerebellar contusion. In the other two cases, delayed epidural hemorrhage ensued and the symptoms disappeared rapidly after evacuation of the hematoma. In these patients, occurrence of delayed epidural hematoma in the posterior cranial fossa was predicted by MR imaging. The authors regard the lesion as an alarm signal indicating the probable occurrence of infratentorial hematoma.

Nociceptive responses of trigeminal neurons in SII-7b cortex of awake monkeys.

A cluster of trigeminal nociceptive neurons was located in the lateral sulcus on the upper bank of the frontoparietal operculum in a region bordering between cortical areas SII and 7b. These neurons were isolated in cortical cell layers IV and V-VI. All nociceptive neurons responded exclusively to noxious mechanical stimulation of cutaneous receptive fields on the face/head or intraoral tissue. Sustained noxious mechanical stimulation elicited slowly adapting responses that accurately encoded the duration of the stimulation. Prolonged discharges following removal of noxious stimulation were not observed. These nociceptive specific neurons poorly encoded graded noxious stimuli. Trigeminal somatosensory neurons within and surrounding the SII-7b cluster were not topographically organized according to divisions of the trigeminal nerve, laterality of receptive fields, or division of face/head and intraoral receptive fields. The thalamocortical, corticocortical and indirect corticolimbic connectivities of SII and area 7b and the possible role of SII-7b nociceptive neurons in learning, memory and avoidance behaviors are discussed.

[Identification of location of electrode tip during percutaneous retrogasserian glycerol injection (PRGI) with blink reflexes elicited by direct stimulation of trigeminal complex (DBR)].

In order to identify the location of the electrode tip during percutaneous retrogasserian glycerol injection (PRGI), the blink reflex (DBR) following direct stimulation of the trigeminal complex (the gasserian ganglion, trigeminal rootlets, or the 3rd division of the trigeminal nerve) was obtained from 6 patients with trigeminal neuralgia. 1) The waveform of the DBR was very similar to that of the blink reflex (BR) elicited by percutaneous stimulation of the 1st division of the trigeminal nerve. However, the latency of early reflex (R1) as well as late reflex (R2) of the DBR was approximately 2 msec shorter than that of the conventional BR. 2) When the electrode tip was introduced into the gasserian ganglion, the DBR showed the largest response under the same recording condition, whereas the DBR was not recorded when the tip of the electrode was placed into either the arachnoid space or the subdural space. The each DBR response, however, showed the same configuration when the electrode tip was situated at the territory of the 1st, 2nd or 3rd division of the trigeminal nerve within the gasserian ganglion or the trigeminal cistern. 3) The DBR always appeared under the anesthesia with the intravenous administration of 10 mg diazepam and 30 mg pentazocine. 4) Based on the present study, the DBR proved to be an usuful parameter in determining whether the electrode tip is introduced into the trigeminal complex or not, particularly in the case of patients having no reliable sensory response to electrical stimulation.

[CT-guided stereotactic brachytherapy in deep-seated malignant gliomas--interstitial irradiation by double-catheter after-loading method].

CT-guided stereotactic brachytherapy has been performed for the deep-seated malignant gliomas using the double-catheter after-loading method. The catheter system consists of two coaxial polyethylene tubes with closed tips. The outer catheter is 3.0 mm in outer diameter and 2.4 mm in inner diameter. The inner catheter is 2.0 mm in outside diameter and 1.4 mm in inside diameter, and contains the radioactive sources. Localization of the target volume is determined by the preoperative findings of computed tomography (CT), magnetic resonance imaging (MRI), and cerebral angiography. Dosimetry and dose planning are so finalized for the target volume as to be irradiated interstitially more than tumoricidal dose. After stereotactic biopsy of the deep-seated brain tumors, stereotactic implantation of the outer catheters is performed using Iseki Stereotactic System in the CT room. Burr holes had been previously opened in the operating room. The inner catheters containing nonradioactive sources (dummy sources) are inserted, and skull X-p is taken to confirm the position of the dummy sources, and to calculate the dosimetry by computer. The inner catheters are replaced with catheters containing radioactive sources (226Ra) in the irradiation room. 226Ra sources deliver at least 500 rads/day (approximately 20 rads/hr) to the target volume as interstitial irradiation. Two patients of malignant gliomas treated with this procedure were shown as representative cases. These patients underwent CT-guided stereotactic brachytherapy as "boost" combined with conventional external irradiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Short latency somatosensory-evoked potentials--direct recording from the human midbrain and thalamus.

Short latency somatosensory-evoked potentials were recorded from the human thalamus and the midbrain during stereotactic operations. Several subcomponents were recognized on the peak of N18. These were recorded with maximal amplitude at the border between the caudal portion of the thalamus and the rostral midbrain. Two positive-negative responses, not previously shown, were observed between P14 and N18. These responses were prominent in the rostral midbrain. These findings indicate that the ascending phase of N18, and the N18 itself, are the compound potential generated in the mesodiencephalic junction.

Surgical treatment of hypertensive intracerebral haematoma by CT-guided stereotactic surgery.

Ninety consecutive cases of hypertensive intracerebral haematoma were treated with CT guided stereotactic evacuation. The patients were composed of 61 males and 29 females, ranging from 42 to 87 years old. The location of haematoma was either in the putamen (59 cases) or in the thalamus (31 cases). The average volume of the evacuated haematoma was 21.4 ml in the putaminal haematoma and 14.0 ml in the thalamic haematoma. Postoperative follow-up study in 46 patients showed good recovery of neurological deficits both in putaminal and thalamic group. Criteria of surgical indication of CT-guided stereotactic evaluation of intracerebral haematoma were advocated based on the author's clinical experience.

[A new treatment of hypertensive intracerebral hematoma--a follow-up study on 46 patients with hematoma treated by CT guided stereotactic method].

During the last 2 years, 46 cases of hypertensive intracerebral hemorrhage in the basal ganglia were treated by CT guided stereotactic aspiration and their outcome was evaluated in terms of the rate of hematoma removal, the change of consciousness level and the recovery of motor and sensory functions. They are aged from 45 to 79 years old, the average 56, and aspirated 1 to 24 days after the onset, two third of them being within 1 week. The whole procedure was done in the CT room under direct CT guidance and by one trial. In putaminal type hemorrhage, the removed hematoma volumes ranged from 9 to 48 ml, average being 23.7 ml, in thalamic type from 5 to 29 ml, average being 15.5 ml. The average rate of removal was 81.1% in 30 cases within 1 week. In most cases, preoperative consciousness was not severely disturbed, in putaminal type, 19 were alert or confused, 4 somnolent, 5 stuperous and in thalamic type, 6, 6, 3 respectively and 2 were semicomatous, one of them had herniation sign. In putaminal type all but 2 cases recovered to alert or confused state, the first one had postoperative bleeding and the other was already apallic preoperatively. In thalamic type, we lost 3 cases, 2 by gastrointestinal bleeding and 1 DIC, by rehemorrhage 2 months after the operation. All but one who was semicomatous preoperatively recovered to alertness. In motor function, some cases of the putaminal bleeding with intact internal capsule remained hemiplegic. On the other hand, most of the cases with partial destruction of the internal capsule on CT recovered well in both types of hematoma.(ABSTRACT TRUNCATED AT 250 WORDS)

[Significance probability mapping of brain electrical activity--its problem and specified z-statistic mapping].

Significance probability mapping (SPM) of brain electrical activity first described by Duffy et al. is useful tool for studying functional aspects of brain disease. Z-statistic SPM is able to identify the area of brain electrical activity deviated with statistic significance from the control group. The problem of this method is, however, that the nature of deviation, i.e., whether it is increase or decrease of electrical activity, can not be displayed. From this point of view, we attempted to use modified z-statistic method. Statistically deviated region and its nature can be clearly displayed on the same picture by analyzing EEG with this method. This method can be applied to SPM of evoked potentials. SPM is not yet complete method for the assessment of brain electrical activity, but there is much room for adopting other statistic method that is more suitable for the aim of the study. Functional aspects of the brain will be more readily clarified by the use of modified SPM and by combination with findings of CT scan, NMR and PET that can give morphological and metabolic information.

[Influence of hemisphere lesions on the contralateral blink reflex].

Electrically elicited blink reflexes were investigated in 28 patients with unilateral hemispheral lesion. The reflex evoked by electrical stimulation of the supraorbital nerve contralateral to the side of the hemispheral lesion was absent or depressed in 14 out of 28 cases. The abnormal patterns of the blink reflexes were devided into four different types (Type AB, Type AD, Type EB, and Type AB-EB). The Type AB, recorded in 4 cases, consisted of bilateral absence of late component (R2) when the supraorbital nerve on the non-lesion side was stimulated. In contrast, the reflex responses were almost normal bilatarally when the stimulus was applied to the nerve on the lesion side. The Type AD was observed in 2 cases. When the stimulus applied on the non-lesion side, both ipsilateral and consensual R2 were markedly delayed in latency. The Type EB was seen in one case. In this type the absence of the late component (R2) was confined to the clinically affected side independent of the side of stimulation. The Type AB-EB was observed in 4 cases. This type consisted of bilateral absence of R2 component after stimulation on the non-lesion side as seen in Type AB. However, when the stimulus applied on the lesion side, R2 component was only elicited on the ipsilateral side of stimulation. Based on our results, the authors emphasize that abnormality of the contralateral blink reflex in the patients with unilateral hemispheral lesion showed not only Type AB or Type AD but also Type AB-EB which may indicate lowered excitability of bulbar lateral reticular formation of the lower brain stem as well as spinal trigeminal system. This type was presumably due to loss of facilitatory influences associated with the contralateral hemispheral lesion, closely correlated with the lower postcentral region advocated by Ongerboer de Visser.

[Ascending limb of the N20 component of somatosensory evoked potential--an analysis on direct recording from the human midbrain].

Somatosensory evoked potential elicited by median nerve stimulation at the wrist was recorded from five loci on the trajectory of stereotactic rostral mensencephalic reticulotomy. Four distinct positive waves followed by one negative wave, the peak latency being 16.3 msec, were recorded from the rostral midbrain reticular formation near the medial lemniscus. The four positive waves were named as I, II, III, and IV respectively. Peak latency of these positive waves was 12.6, 13.7, 14.7 and 15.8 msec respectively. The first two positive waves (I, II) corresponded to P13 and P15 recorded over the scalp. The other two positive waves (III, IV) changed their polarity to negative at the level of the ventral thalamus and formed the ascending limb of N20 recorded over the scalp. N16 was most prominent at the level of nucleus ventrocaudalis externus. These findings suggest that the ascending limb of N20 is composed of at least three components, wave III, IV, and N16. The present report is compatible with the investigations by Abbruzzese et al.2) and Eisen et al.11) that there are several distinct dipoles between P15 and N20 of somatosensory evoked potential in man.

Long-term follow-up study of rostral mesencephalic reticulotomy for pain relief--report of 34 cases.

A long-term follow-up study of rostral mesencephalic reticulotomy (RMR) for pain relief is presented. 34 patients (24 males and 10 females) were operated. Ages ranged from 18 to 65 years. The follow-up period was 1-70 months. The overall effectiveness of RMR showed good relief of pain in 23 patients (67%). The study of effectiveness of RMR according to type of pain showed good relief of pain in 5 out of 6 patients (83%) with nondenervation pain, whereas satisfactory pain relief was obtained in 18 out of 28 patients (64%) with denervation pain.

[An assessment of outcome prediction in patients with severe brain damage with auditory brainstem response and blink reflex].

Results of auditory brainstem response (ABR) and electrically elicited blink reflex (BR) recorded from 43 patients with severe brain damage within three days after the onset of illness were analyzed to assess the prognostic value of ABR and BR with respect to patient outcome evaluated by the criteria proposed by Jennett and Bond. It was possible to recognize, in recordings obtained from patients with severe brain damage, three basic patterns of BR as well as five patterns of ABR within three days after the onset. Three basic patterns of BR were composed of Type I, which closely approximated the BR of normal subjects except for moderately prolonged latency of R2, Type II, which indicated absence of bilateral R2 activities, and Type III, which showed absence of R1 as well as bilateral R2. ABRs were graded, in increasing order of abnormality, from Type I to Type V. Type I was almost normal pattern from wave I to wave V. Type II indicated prolonged latency or markedly reduced amplitude of waves IV and V. Type III showed absence of waves IV and V. Type IV had only wave I. Type V indicated absence of all waves. BR abnormalities significantly proved useful in predicting vital prognosis of the comatose patients with supratentorial lesion. In patients who had Type II of BR, additional studies of ABR enhanced the reliability of prediction of functional prognosis. On the other hand, ABR was recognized as stronger basis for predicting outcome in patients with infratentorial lesion. All patients with Type IV or Type V of ABR were expired within one month after the onset.(ABSTRACT TRUNCATED AT 250 WORDS)

[Evaluation of anticonvulsant-induced bone changes by a microdensitometric method].

The effect of long-term anticonvulsants on bone change was evaluated by microdensitometric method (MD method) in 221 outpatients of Neurological Institute Tokyo Women's Medical College. Laboratory findings including serum Ca, P, Al-p were compared with severity of bone change. Following results were obtained; In 221 patients, 159 cases (72%) were normal, 31 cases (14%) were in the initial stage of abnormality, 23 cases (10%) in grade I, 7 cases (3%) in grade II and one case (1%) in grade III of abnormality. Incidence of abnormality was high in the age of 26-35 years old and in the age over 56 years old. Total dose, serum concentration of diphenylhydantoin (DPH) as well as phenobarbital (PB) and also duration of administration of PB correlated positively with severity of bone change. Duration of administration of DPH and valproic acid (VPA), total dose and serum concentration of VPA did not correlate with severity of bone change. Serum Ca correlated with severity of bone change, but P and Al-p did not correlate with severity of bone change. Pattern of bone change was estimated by two parameters of MD method (MCI and GSmax). Results showed that most of the osteopathy (grade I-III by MD method) fell into osteoporotic type. Based on these results, it is suggested that roentgenologic and biochemical supervision of the patients is required during long-term anticonvulsant therapy.

[A new apparatus and stereotactic method for percutaneous high cervical cordotomy].

The authors devised a stereotactic apparatus for percutaneous cordotomy based on the experience of 191 percutaneous high cervical cordotomies on 150 patients suffering from intractable pain. This apparatus has two major components. One is a head and neck holder and the other is a guide and marker system. The head and neck holder contains fixed neck holder and head holder which can be movable in vertical direction. Using these holders, the operator can keep the patient's neck in neutral position. The marker system contains two markers of origin and a 10mm scale which indicates center line as well. The guide system, stereotactically designed, is movable in three direction and acrylic guide groove is attached. The guide needle for percutaneous cordotomy is inserted along the guide groove. The guide and marker system can be attached in both sides of the head and neck holder, therefore, the operator can insert the needle in both sides of the patient. This apparatus makes it possible to locate the target stereotactically for percutaneous cordotomy, since location of the inserted needle can be determined with the aid of cervical X-ray, even if there is no image intensifier of TV display screen available. Therefore it can be possible to reduce the X-ray exposure of the patient.

CT-guided stereotactic surgery for evacuation of hypertensive intracerebral hematoma.

During the last 3 years, 46 cases of hypertensive intracerebral hemorrhage were treated by CT-guided stereotactic surgery. Our present report is concerned with the evaluation of this procedure in the treatment of hypertensive intracerebral hematoma, in terms of the rate of aspirated hematoma and follow-up study of patients. It is difficult to draw any definite conclusion about the operative indications. CT-guided stereotactic aspiration, however, can be evaluated as a less invasive and more definitive treatment of intracerebral hematoma in the basal ganglia and thalamus.

A new apparatus for CT-guided stereotactic surgery.

Combining whole-body CT scan with a stereotactic system, the authors have developed and applied clinically an apparatus which readily provides intraoperative CT images, making it possible to confirm the location of the target point and ascertain the intraoperative environment. It takes about 9 s to obtain a CT image. Our purpose is to make stereotactic surgery, a kind of blind surgery, as safe and reliable as a visualized procedure by intraoperative CT scanning. By the method, in which there is very little invasion under local anesthesia, evacuation of deep-seated intracerebral hematomas as well as brain abscesses and also biopsy or brachytherapy of brain tumors in the brain can be done with safety and reliability.

[The incidence of postoperative epilepsy and prophylactic anticonvulsants in patients with intracranial aneurysm].

The occurrence of epileptic seizures is not rare after craniotomy. The authors examined the incidence of postoperative epilepsy in 150 patients of intracranial aneurysm. Anticonvulsants were given to all patients after operation, but in 12 cases anticonvulsants were discontinued because of liver dysfunction. One hundred and eight out of 138 cases (78%) were prescribed polypharmaceutically, and 30 of 138 cases (22%) were monopharmaceutically. The daily dose of anticonvulsants was as follows; diphenylhydantoin (DPH) was 150-300 mg, phenobarbital (PB) was 50-100 mg, valproic acid (VPA) was 600-1200 mg, and carbamazepin (CBZ) was 200-600 mg. Postoperative epilepsy occurred in 14 of 150 cases (9.3%); 13 cases with anticonvulsants, and 1 case without anticonvulsants. The site of aneurysm was as follows; 6 cases (10.3%) of AC aneurysm, 3 cases (9.7%) of MC aneurysm, 1 case (2.4%) of IC aneurysm, and 4 cases (21.1%) of multiple aneurysm. The interval between operation and epileptic seizure was ranged 2 to 57 months (mean 19.8 months); in 7 cases (50%) within 1 year, and in 13 cases (93%) within 3 years. The authors emphasize that prophylactic use of anticonvulsants is effective to control subclinical epileptic seizures, prescribing anticonvulsants to all patients after craniotomy in general. The medication of anticonvulsants for 3 years would be necessary for avoiding postoperative epileptic seizure.