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PubMed2000

Midbrain hemorrhage presenting with trochlear nerve palsy.

A 40-year-old normotensive man suddenly developed diplopia, tinnitus and a burning sensation on the left side of his body while driving a motorcycle. He did not complain of headache, nausea or vomiting. Neurologic examination revealed left trochlear nerve palsy and impaired pinprick, temperature and joint position sensation of the left limbs. There was no ptosis or motor deficit. He had a mild bleeding diathesis due to alcoholic liver cirrhosis. Computerized tomography and magnetic resonance image of the brain disclosed hemorrhages in the right midbrain tectum and the left temporal lobe. After nine months of observation, there was nearly complete recovery of symptoms, except for mild residual diplopia. From a literature review, only nine case of midbrain tectal hemorrhage involving the inferior colliculus have been reported. These patients had a unique clinical presentation. Diplopia due to trochlear nerve palsy, either unilateral or bilateral, was present in all of the cases. Tinnitus and sensory disturbance contralateral to the lesion side were very common. Only three patients had risk factors for hemorrhage, including bleeding diathesis, hypertension and vascular anomalies. In the majority of patients, no underlying causes were detected. The outcome was favorable with conservative treatment.

Adult↗
PubMed1998

Trochlear nerve enhancement on three-dimensional magnetic resonance imaging in Fisher syndrome.

PURPOSE: To examine the lesion associated with external ophthalmoplegia in Fisher syndrome using three-dimensional magnetic resonance imaging (3-D MRI). METHOD: Case report. A 65-year-old woman with Fisher syndrome was investigated by gadolinium-enhanced 3-D MRI. RESULT: The extramedullary portion of the left trochlear nerve was enhanced. CONCLUSION: Contrast-enhanced 3-D MRI revealed that the lesion responsible for the external ophthalmoplegia in Fisher syndrome is located in the extramedullary portion of the trochlear nerve.

Aged↗
PubMed1995

Transient trochlear nerve palsy following anterior temporal lobectomy for epilepsy.

Three of 22 patients (14%) who underwent anterior temporal lobectomy for treatment of medically intractable epilepsy at our institution from July 1987 through July 1993 experienced diplopia immediately after surgery. We found ipsilateral paresis of the superior oblique muscle in all three patients. Their ophthalmoplegia resolved completely within 14 weeks. We did not observe any new structural or ischemic changes on postoperative MRIs to account for their deficits. Trochlear nerve palsy--not oculomotor nerve palsy, as is reported in most reference texts--is a relatively common cause of transient diplopia following temporal lobectomy. Indirect (ie, traction) injury of the trochlear nerve is a plausible mechanism that would explain this complication.

Adult↗
PubMed2004

Ocular rotation axes during dynamic Bielschowsky head-tilt testing in unilateral trochlear nerve palsy.

PURPOSE: To explain the positive Bielschowsky head-tilt (BHT) sign in unilateral trochlear nerve palsy (uTNP) by the kinematics of three-dimensional eye rotations. METHODS: Twelve patients with uTNP monocularly fixed on targets on a Hess screen were oscillated (+/- 35 degrees, 0.3 Hz) about the roll axis on a motorized turntable (dynamic BHT). Three-dimensional eye movements were recorded with dual search coils. Normal data were collected from 11 healthy subjects. RESULTS: The rotation axis of the viewing paretic or unaffected eye was nearly parallel to the line of sight. The rotation axis of the covered fellow eye, however, was tilted inward relative to the other axis. This convergence of axes increased with gaze toward the unaffected side. Over entire cycles of head roll, the rotation axis of either eye remained relatively stable in both the viewing and covered conditions. CONCLUSIONS: In patients with uTNP, circular gaze trajectories of the covered paretic or unaffected eye during dynamic BHT are a direct consequence of the nasal deviation of the rotation axis from the line of sight. This, in turn, is a geometrical result of decreased force by the superior oblique muscle (SO) of the covered paretic eye or, according to Hering's law, increased force parallel to the paretic SO in the covered unaffected eye. The horizontal incomitance of rotation axes along horizontal eye positions can be explained by the same mechanism.

Adolescent↗
PubMed1999

Bilateral trochlear nerve palsy associated with cryptococcal meningitis in human immunodeficiency virus infection.

This is the report of a case of bilateral trochlear nerve palsy secondary to cryptococcal meningitis in a 34-year-old woman with acquired immune deficiency syndrome. Based on clinical and neuroradiologic findings, it is concluded that in the present case, a postinflammatory shrinking of the arachnoid has stretched the fourth cranial nerves at their point of emergence from the dorsal surface of the brainstem.

AIDS-Related Opportunistic Infections↗
PubMed1992

Combined trochlear nerve palsy and internuclear ophthalmoplegia.

We report a case of left superior oblique palsy combined with a right internuclear ophthalmoplegia. A right mesencephalic lesion involving the trochlear nerve nucleus (or its fibers prior to decussation) and the medial longitudinal fascicle was hypothesized. Magnetic resonance imaging showed a lesion at the suspected level.

Adult↗
PubMed2004

Intracranial portion of the trochlear nerve and dorsal oblique muscle composition in dog: a structural and ultrastructural study.

In the present investigation the right intracranial portion of the trochlear nerves and dorsal oblique muscle of the right ocular globe were removed from six adult dogs and analyzed by light and electron microscopy. Unmyelinated fibers were observed in the analyzed nerves. The number, diameter, area, and density of myelinated fibers were determined, as were corresponding axon area and diameter and myelin sheath thickness. Frequency histograms of myelin sheath thickness and fiber size show a bimodal distribution with a similar proportion of large and small fibers. Muscle samples were taken from the central portion of the muscle belly, subsequently frozen, cut, and stained with m-ATPase at pH 4.6. Fibers were classified as Type 1 or Type 2 according to their reaction to the m-ATPase and detailed morphologic and morphometric studies were made. The muscles showed two clearly distinct layers, a central layer and a peripheral layer, chiefly composed of Type 2 fibers. The fibers in the central layer were larger in size than those in the peripheral layer.

Animals↗
PubMed2000

Development of the trochlear nerve in the human embryos.

Investigations were made on serial sections of human embryos at developmental stages from 13 to 23 (32-56 postovulatory days). The trochlear nucleus appears in the posterior region of the basal plate of the midbrain at stage 13. It is composed of large neurons, the processes of which are sharply defined. Since stage 15 the trochlear fibers can be followed through the alar region to their decussation in the mid-dorsal part of the midbrain. The trochlear nerve emerges from the dorsal surface of the lowest part of the midbrain.

Embryo, Mammalian↗
PubMed1994

Isolated trochlear nerve palsy secondary to dural carotid-cavernous sinus fistula.

Ophthalmoplegia associated with dural carotid-cavernous sinus fistula typically involves the third, fourth, and sixth cranial nerves. Occasionally, isolated palsy of the oculomotor or abducens nerve is noted. We report a patient with bilateral dural carotid-cavernous sinus fistulas who presented with an isolated trochlear nerve palsy.

Arteriovenous Fistula↗
PubMed1977

Aging in the human brain stem. A study of the nucleus of the trochlear nerve.

As a part of a continuing study of the relationship between age and neuronal population within the human brain stem, the nucleus of the trochlear nerve was examined in a total of 20 brains from newborn to 87 years of age. The cell count in the newborn was 1,830, and in the 87-year-old 2,010, while the mean number for all the specimens examined was 2,115. It is apparent that there is no cell loss in this nucleus in the normal aging process, which is in accord with the findings in five other brain stem nuclei examined by various investigators. This is in contrast to the findings in cerebral and cerebellar cortex which show significant cell loss with advancing age. Based on this and previous studies of the brain stem nuclei, it appears that neuronal loss is not a concomitant of the normal aging process in the brain stem. The anatomical basis of this selectivity in neuronal loss with aging in certain parts of the brain is not known at present.

Adolescent↗
PubMed1988

Changes of the ratio between myelin thickness and axon diameter in human developing sural, femoral, ulnar, facial, and trochlear nerves.

Previous studies on sural nerves were extended to human femoral, ulnar, facial and trochlear nerves. As asynchronous development of axon diameter and myelin sheath thickness was noted in all nerves studied. Whereas axons reach their maximal diameter by or before 5 years of age, maximal myelin sheath thickness is not attained before 16-17 years of age, i.e., more than 10 years later. The slope of the regression lines for the ratio between axon diameter and myelin thickness is significantly steeper in older than in younger individuals; it also differs if small and large fibers with more or less than 50 myelin lamellae are evaluated separately. The number of Schmidt-Lanterman incisures during later stages of development is related to myelin thickness, but the length of the spiral of the myelin lamella, thought to unrolled, in relation to its width, i.e., internodal length, varies considerably during development. The changes of the relationship between axons and myelin sheath thickness during normal human development have to be taken into account if hypomyelination is considered as a significant pathological phenomenon in peripheral neuropathies, especially in children. The implications of the present findings concerning conduction velocity of peripheral nerve fibers and other electrophysiologic parameters are discussed.

Adolescent↗
PubMedDate not supplied

Trochlear nerve palsy associated with superficial siderosis of the central nervous system.

A 56-year-old man with superficial siderosis of the central nervous system (SSCN) presented with complaints of trochlear palsy, visual field defects, gait ataxia, and hearing loss. He had no history of trauma and there were no signs of tumors or aneurysms. T2-weighted magnetic resonance imaging demonstrated characteristic hypointensity in the meninges. We believe that SSCN should be added to the differential diagnosis of trochlear nerve palsy.

Brain Diseases↗
PubMed2005

Comparison of Harms tangent screen and search coil recordings in patients with trochlear nerve palsy.

Harms tangent screen, a subjective measurement method of three-dimensional binocular alignment, was compared with search coil recording. Twenty-three patients with unilateral trochlear nerve palsy were measured in nine gaze positions. The two methods correlated best for the horizontal gaze deviation, the vertical gaze deviation, and the vertical incomitance, but there was no correlation for the results of torsional incomitance. Using Harms tangent screen, torsional deviation underestimated the torsional incomitance measured by the search coils. Therefore, central torsional fusional mechanisms or alignment error in the Harms tangent screen are assumed.

Adolescent↗
PubMed2004

Transient isolated trochlear nerve palsy associated with Rathke's cleft cyst.

We report the case of a 52-year-old woman who developed vertical diplopia of 1-days duration. Neuro-ophthalmological testing revealed left trochlear nerve palsy, and sellar MRI revealed a 1.5 cm-sized pituitary mass lesion, a Rathke's cleft cyst. The diplopia disappeared spontaneously after 6 days.

Central Nervous System Cysts↗
PubMed1986

Trochlear nerve pareses with brainstem lesions.

Three cases of radiographic localization of fourth nerve lesions are reported: case 1--bilateral pareses due to traumatic contusion; case 2--left paresis from a collicular gunshot wound; and case 3--bilateral pareses due to a (cysticercal) cyst in the caudal cerebral aqueduct.

Adult↗
PubMed1978

Observations on the development of the connective tissues of developing human nerve.

Trochlear nerves from two human fetuses, and digital nerves from a third, have been examined by electron microscopy. Very marked differences in maturation were found between trochlear nerves of fetuses of ages differing only by 2--3 weeks, and between proximal and distal parts of the same trochlear nerve. Immaturity was reflected in paucity of endoneurial space and collagen and in the rarity, or virtual absence, of endoneurial fibroblasts. Circumstantial evidence of collagen formation by Schwann cells has been presented and discussed.

Axons↗