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Regeneration of nerve fibres in the anterior medullary velum of neonatal and weanling rats.

The responses to injury of myelinated central axons in neonatal (5-day) and weanling (30-day) rats were compared, using the trochlear nerve fibres in the anterior medullary velum (AMV) as an experimental system. In intact animals, fibres of the trochlear nerve decussate completely in the AMV, to enter the contralateral nerve. Sprouting from proximal axon stumps was seen within 36 h after injury in silver-stained, whole mounts of mid-sagittally lesioned AMVs from weanlings. Subsequent growth produced a tangled axon mass which persisted until 15-20 days post-lesion (d.p.l.) but then began to degenerate. By 50 d.p.l., the majority of surviving axons looped within the AMV to enter the ipsilateral trochlear nerve; few axons remained growing randomly within the AMV. Axonal debris persisted within the velum 50 d.p.l. In neonatal rats, lesioned trochlear axons initially developed axon sprouts, but then degenerated with rapid clearance of debris, leaving the AMV devoid of both axons and degeneration products by 6 d.p.l. From 8 d.p.l., the velum became repopulated by axons which either grew randomly or looped to enter the ipsilateral peripheral nerve. Both patterns of axon growth were still observed 50 d.p.l. In both experimental groups, horseradish peroxidase injection to the right superior oblique muscle 40 d.p.l. indicated that at least some of the looping fibres observed within the lesioned AMVs originated in the ipsilateral trochlear nucleus. The origin of those axons growing randomly within the AMVs of neonatally-lesioned animals is unknown. The results are discussed with reference to current ideas concerning regeneration-inhibiting elements in the CNS, and regeneration-promoting factors in the PNS.

Aging↗

Proposed treatment strategy for cavernous sinus meningiomas: a prospective study.

OBJECTIVE: To establish a safe and effective treatment strategy for cavernous sinus (CS) meningiomas, we prospectively analyzed the outcome of a treatment protocol combining surgery and radiosurgery during the past 7 years. METHODS: Tumors confined to the CS and distant from the optic apparatus and the brainstem were treated with radiosurgery alone. Tumors attached to or compressing the optic apparatus and brainstem and that were larger than 3 cm in mean diameter, extended into the multiple cranial fossae, and were suspected of being malignant were treated with combined nonradical microsurgery and radiosurgery. RESULTS: In accordance with this treatment protocol, 40 patients aged 26 to 72 years (median, 51 yr) with primary (n = 27) or recurrent (n = 13) CS meningiomas (volume range, 0.9-39.3 cm(3); median volume, 5.4 cm(3)) were treated with combined surgery and radiosurgery (n = 23) or radiosurgery alone (n = 17). During radiosurgery, 12 to 18 Gy (median, 16 Gy) was delivered to the tumor margin. The follow-up period ranged from 14 to 79 months (median, 47 mo). The actuarial tumor control rate was 94.1% at 5 years. The improvement of cranial nerve function was significantly frequent in patients with primary CS meningiomas (P < 0.05). Permanent cranial nerve dysfunction was significantly frequent in patients with tumors compressing the brainstem or smaller than 10 cm(3) (P < 0.05). All 36 patients with a pretreatment Karnofsky Performance Scale score of 90 or more maintained the same range after treatment. CONCLUSION: Proper combination of microsurgery and radiosurgery for CS meningiomas provides excellent growth control with favorable functional state. Outcomes were better when this protocol was adopted at the initial diagnosis for patients with smaller tumors that did not compress the brainstem.

Adult↗

Numerous transorbital wooden foreign bodies in the sphenoid sinus.

A very rare case of numerous transorbital wooden foreign bodies penetrating into the sphenoid sinus in a 47-year-old male is reported. His right eye was nonreactive to light, and the oculomotor, trochlear and abducens nerves were completely disturbed. Although a minor injury was observed on the inner side of the right eyebrow, the wound was not serious or infectious. Computed tomographic scanning of the orbit and parasinus revealed an isodense linear shadow to muscle and an irregular shadow of the lamina papyracea. However, the findings were difficult to discriminate from an optic canal fracture preoperatively. We detected foreign bodies penetrating the optic nerve rise, which were successfully removed in combination with an endoscopic transethmoidal and transorbital approach. Various and careful imaging examinations are recommended to diagnose and manage paraorbital trauma, when a penetrating wound of the face is observed.

Blindness↗

Neuronal response of the hippocampal formation to injury: blood flow, glucose metabolism, and protein synthesis.

The reaction of the hippocampal formation to entorhinal lesions was studied from the viewpoints of cerebral blood flow ([123I]isopropyl-iodoamphetamine[IMP])-glucose utilization ([14C]2-deoxyglucose), and protein synthesis ([14C]leucine), using single- and double-label autoradiography. Our study showed (i) decreased glucose utilization in the inner part, and increased glucose utilization in the outer part of the molecular layer of the dentate gyrus, starting 3 days after the lesion; (ii) increased uptake of [123I]IMP around the lesion from 1 to 3 days postlesion; and (iii) starting 3 days after the lesion, marked decrease in [14C]leucine incorporation into proteins and cell loss in the dorsal CA1 and dorsal subiculum in about one-half of the rats. These changes were present only in animals with lesions which invaded the ventral hippocampal formation in which axons of CA1 cells travel. By contrast, transsection of the 3rd and 4th cranial nerves resulted, 3 to 9 days after injury, in a striking increase in protein synthesis in the oculomotor and trochlear nuclei. These results raise the possibility that in some neurons the failure of central regeneration may result from the cell's inability to increase its rate of protein synthesis in response to axonal injury.

Amino Acids↗

A trochlear stroke.

Explore the source record for details and available documents.

Brain Stem Infarctions↗

Neurologic eye signs following motorcycle accidents.

A review of 96 consecutive patients who suffered neuro-ophthalmologic injuries in motorcycle accidents revealed a wide range of findings. These findings were similar to signs associated with other forms of closed-head trauma, aside from a higher incidence of trochlear nerve palsies.

Accidents, Traffic↗

Traumatic trochlear nerve palsy diagnosed by magnetic resonance imaging: case report and review of the literature.

Although head trauma is the leading cause of acquired trochlear nerve dysfunction, it receives little attention in the neurosurgical literature. A case is reported of closed head injury that resulted in a right superior oblique palsy in association with incoordination on the left side. Diagnostic imaging revealed a normal cranial computed tomographic scan and a left dorsal midbrain lesion on magnetic resonance imaging scan. The relevant anatomy is reviewed, as well as the action of the superior oblique muscle, its agonists and antagonists, and the clinical manifestations of superior oblique dysfunction. This case is one of the few we are aware of in which a relatively isolated trochlear nerve palsy is the result of a lesion that can be documented by diagnostic imaging, and the first in which the imaging modality is magnetic resonance imaging scan.

Adult↗

Relationships of the cisternal segment of the trochlear nerve.

OBJECT: The cisternal portion of the trochlear nerve (fourth cranial nerve) can easily be injured during intracranial surgical operations. To help minimize the chance of such injury by promoting a thorough understanding of the anatomy of this nerve and its relationships to surrounding structures, the authors present this anatomical study. METHODS: In this study, in which 12 cadaveric heads (24 sides) were used, the authors describe exact distances between the trochlear nerve and various surrounding structures. Also described are relatively safe areas in which to manipulate or enter the tentorium, and these are referenced to external landmarks. CONCLUSIONS: This information will prove useful in planning and executing surgical procedures in and around the free edge of the tentorium cerebelli.

Aged↗

Trochlear nerve palsy after repeated percutaneous balloon compression for recurrent trigeminal neuralgia: case report and pathogenic considerations.

OBJECTIVE AND IMPORTANCE: Repeated percutaneous balloon compression for the treatment of idiopathic trigeminal neuralgia is infrequent. When a second procedure is performed, the outcome is unknown. A patient developed an isolated trochlear nerve palsy after undergoing percutaneous trigeminal ganglion balloon compression for a second time. The mechanism of diplopia and the complications associated with this technique were studied. CLINICAL PRESENTATION: The patient was a 67-year-old woman with a history of medically refractory idiopathic trigeminal neuralgia involving all three divisions of the right trigeminal nerve. INTERVENTION: Percutaneous balloon compression was performed. Despite initial total relief from pain without complications, the patient again displayed manifestations of trigeminal neuralgia 3 months after the procedure. The pain disappeared after she underwent a second balloon compression procedure, but she developed an isolated trochlear nerve palsy, which spontaneously resolved in 2 months. CONCLUSION: Isolated trochlear nerve palsy is a rare and reversible complication after percutaneous balloon compression for trigeminal neuralgia. This case illustrates that the mechanism of injury to the fourth nerve is the result of an erroneous technique: excessive penetration of the Fogarty catheter in Meckel's cave beyond the porus trigemini and compression of the cisternal segment of the trochlear nerve when the inflated balloon is pushed against the tentorium.

Aged↗

[A case of solitary and unilateral trochlear nerve palsy due to a blunt head impact].

A case of solitary and unilateral trochlear nerve palsy following a minor, blunt head impact is reported. A 72-year-old man fell down backwards from the top of a staircase having 13 steps and hit his right parietal head and shoulder. Routine neurological examination revealed no remarkable findings, however, the subject complained of double vision when he focused downwards. The computed tomography four hours after the initial impact showed a localized small high-density lesion on the left quadrigminal cistern. The magnetic resonance imaging also indicated subarachnoid bleeding expressed by the low-intensity area in T2 weighted images in the same place. There was no evidence of any contusion within the midbrain. Hess chart test clearly showed solitary left superior oblique muscle palsy. The manner of the injury was thought to be quite typical, since he had hit his right parietal area up-side-down when falling, that is, the accelerated force acted as an impact against the firm floor. This impact caused the midbrain concussion against the cerebellar tentorial notch resulting in a localized subarachnoid hemorrhage which caused the unilateral trochlear nerve palsy.

Aged↗

[Cure of post-traumatic bilateral paralysis of the cranial nerve IV].

We relate our own experience about bilateral inferior rectus recession as first surgery for traumatic bilateral superior oblique palsy. An adjustable suture is performed on one side. This procedure is combined or not with an inferior oblique recession. Measurements of ocular deviation and torsion, Lancaster tests and binocular single vision fields are reported pre- and postoperatively. Reduction of diplopia, cyclodeviation and V esotropia with an expansion of the binocular single vision field is achieved in all cases, relieving patients' complaints. This surgery is easy to perform and free of important secondary effects. We think it represents a valuable choice for that kind of pathology.

Adult↗

A concept for the surgical treatment of trochlear palsy.

The outstanding clinical symptom of acquired uni- and bilateral trochlear palsy is excyclotropia which increases in down-gaze. Any surgical treatment must aim at reducing this deviation. To achieve this, we have routinely used a modification of the Harada-Ito operation over the last 20 years. The anterior part of the tendon is pulled anteriorly and laterally by a loop of unresorbable suture. This not only increases incyclotorsion but also depression in adduction and reduces the V-pattern. In cases with more than 5 degrees vertical deviation, we performed an additional tuck of the posterior part of the tendon. Our results are compared with those of either superior oblique tuck or combined operations on the oblique muscles published by other authors. They have also used the Harms' tangent screen for quantification of the effect of the operations. In down-gaze, similar results have been obtained but less postoperative Brown's syndrome was found with our modified Harada-Ito procedure. Thus, our modification of the Harada-Ito procedure is an effective and safe approach to the surgical treatment of trochlear palsy with less postoperative limitation of elevation and less torsional overcorrection in up-gaze.

Head Injuries, Closed↗

Recovery of fusional convergence after systematic practice.

Fusional convergence was trained systematically with orthoptic devices in three patients with a severe deficit in convergent fusion resulting from vascular (one case) or traumatic (two cases) brain damage. Within a single-subject baseline design two of the three patients showed a significant, and the third patient a moderate, recovery of fusional range. All patients showed a significant improvement in visual acuity for objects close by, improved reading performance and an increase in stereo acuity (two cases). The results suggest a considerable potential for recovery of oculomotor functions in brain-damaged patients when appropriate treatment methods are applied.

Accommodation, Ocular↗

Bilateral fourth-nerve palsy occurring after shaking injury in infancy.

The shaken baby syndrome is a serious form of child abuse that typically results in serious short- and long-term neurological sequelae. Isolated cranial nerve palsies have been reported after shaking injuries in infants. We report a child with bilateral fourth cranial nerve palsy that developed after a shaking injury.

Hematoma, Subdural↗

[Unilateral paresis of the fourth cranial nerve as the only symptom of mesencephalic ischemia].

INTRODUCTION: Lesions of the fourth cranial nerves are infrequently diagnosed in cases of disorder of the oculomotor nerves. Most authors consider head injury to be the usual cause of this lesion, which is also frequently seen in association with a microvascular lesion in persons with blood flow problems. CLINICAL CASE: We present the case of an isolated lesion of the trochlear nerve as a consequence of midbrain ischaemia. CONCLUSIONS: Vascular disorders of the brain stem are an uncommon cause of paresis of the superior oblique muscle of the eye and exceptional as the only symptom.

Aged↗