Trochlear Nerve

We investigated the effect of diagnostic occlusion on the motility pattern of acquired trochlear nerve palsy. PATIENTS AND METHODS: Forty-eight patients aged between 6 and 78 years (median 49 years) with unilateral trochlear nerve palsy were first examined without patching, and then after 3 days of diagnostic occlusion. CONCLUSIONS: In patients with trochlear nerve palsy, diagnostic occlusion regularly causes an increase in excyclodeviation.  

trochlear nerve palsy leads to kinematic aberrations of both the paretic and the unaffected eye.  

RESULTS: The neurovascular relationships in the lateral wall of the cavernous sinus that are visible by the endonasal transsphenoidal approach but not visible by the transcranial microsurgical approach are as follows: between the oculomotor nerve and the tentorial artery, between the distal segment of the trochlear nerve and the tentorial artery, between the ophthalmic nerve and the inferolateral trunk, and between the abducens nerve and the inferolateral trunk. The neurovascular relationships visible by the transcranial microsurgical approach but not visible by the transsphenoidal endoscopic approach are as follows: between the oculomotor nerve and the superoproximal artery, when present, and between the proximal segment of the trochlear nerve and the superoproximal artery.  

OBJECTIVES: To investigate whether ocular torsion and vertical misalignment differ in the upright vs supine position in skew deviation and to compare these findings with those in trochlear nerve palsy. METHODS: Ten patients with skew deviation, 14 patients with unilateral peripheral trochlear nerve palsy, and 12 healthy subjects were prospectively recruited. RESULTS: In patients with skew deviation, the abnormal torsion and vertical misalignment in the upright position decreased substantially with change to the supine position, whereas in patients with trochlear nerve palsy, it changed little between positions. Torsion was decreased by 83% in patients with skew deviation, 2% in patients with trochlear nerve palsy, and 6% in healthy subjects (P < .001). Similarly, vertical misalignment was decreased by 74% in patients with skew deviation and increased by 5% in patients with trochlear nerve palsy and 6% in healthy subjects (P < .001). CONCLUSIONS: Our findings provide the basis for additional clinical tests to support the classic 3-step test: ocular torsion and vertical misalignment that decrease from the upright position to the supine position indicate skew deviation, whereas torsion and vertical misalignment that do not change significantly between positions indicate trochlear nerve palsy..  

METHODS: The trochlear nerve was severed intracranially in two rhesus monkeys.  

BACKGROUND: Various surgical procedures are recommended as treatment for trochlear nerve palsy. PATIENTS AND METHODS: Patients with isolated acquired unilateral trochlear nerve palsy were examined at a distance of 2.5 m from the Harms tangent scale before and 3 months after surgery.  

METHODS: The trochlear nerve was severed intracranially in two rhesus monkeys (M1 and M2). RESULTS: The main findings after trochlear nerve sectioning were (1) the amplitude and peak velocity of torsional quick and slow phases of the paretic eye was less than that in the normal eye for both intorsion and extorsion, and (2) the vertical motion of the paretic eye increased during both torsional slow and quick phases.  

The trochlear nerve was the landmark for opening the cavernous sinus by this approach. The dura located medially to the entry point of the trochlear nerve into the tentorium was resected, allowing exposure of the intracavernous carotid artery with its meningohypophyseal trunk.  

This electrotonic coupling between the oculomotor and trochlear nerve motoneurons may promote the co-activation of the muscles responsible for vertical eye movements..  

CLINICAL PRESENTATION: A 50-year-old patient presented with vertical diplopia resulting from left trochlear nerve palsy.  

The tentorium is sectioned transversally toward its free edge behind the porus of the trochlear nerve.  

Insights gained from molecular genetics have strengthened the hypothesis that CFEOM results from the dysinnervation of the extraocular muscles supplied by the oculomotor and/or trochlear nerves.  

temporalis posterior, trochlear nerve.  

The trochlear nerve and abducent nerve could be observed under endoscope.  

The other two patients, having total oculomotor nerve paralysis combined with trochlear nerve palsy, underwent fixation of the globe to the anterior lacrimal crest by half a tendon width of the medial rectus.  

Although less common, oculomotor and trochlear nerve palsies have been reported as well.  

The diameter of the trochlear nerve in the superior orbital fissure was on average 1.15 +/- 0.19 mm on the right and 1.21 +/- 0.21 mm on the left.  

A 47-year-old woman presented with throbbing headache in her right frontal region followed by right trochlear nerve palsy.  

One patient with a superior cerebellar artery aneurysm presented with isolated trochlear nerve palsy.  

Here we present the case of a 53-year old man with progressive double vision due to isolated left trochlear nerve palsy. Explorative neurosurgical intervention revealed a left trochlear nerve cavernoma. The lesion was microsurgically excised followed by end-to-end anastomosis of the trochlear nerve. To the authors' knowledge, this is the first report on a symptomatic cavernous malformation arising from the trochlear nerve and on its successful surgical management..  

The symptoms improved after steroid pulse therapy, but relapses of transverse myelitis and diplopia due to disturbance of the bilateral abducent nerves and left trochlear nerve occurred 7, 12, 16, and 26 months after treatment.  

Other neurological examinations were normal except for a minor paresis of the left trochlear nerve revealed only by detailed neuroophthalmological examination.  

BACKGROUND: Twenty-six cases of pathologically verified schwannomas of the trochlear nerve have been reported in the literature.  

METHODS: The trochlear nerve was severed intracranially in two rhesus monkeys.  

METHODS: The trochlear nerve was severed intracranially in two rhesus monkeys.  

METHODS: The trochlear nerve was severed intracranially in two rhesus monkeys.  

METHODS: Infrared video recordings of horizontal and vertical eye movements were obtained from 14 adult patients with either unilateral abducens nerve palsy or trochlear nerve palsy.  

Premotor neurons labeled transneuronally after application of wheat germ agglutinin-conjugated horseradish peroxidase into the trochlear nerve were mainly distributed ipsilaterally in the Forel's field H (FFH) and bilaterally in the interstitial nucleus of Cajal (INC).  

RESULTS: The ambient cistern extends from the posterior margin of the crural cistern to the lateral edge of the midbrain colliculi, and round the lateral surface of the upper portion of the brainstem; The ambient cistern mainly contained P(2) segment of the posterior cerebral artery, superior cerebellar artery, anterior choroidal artery, basal vein and trochlear nerve.  

Congenital ocular aberrant innervations can involve oculomotor, trigeminal, abducens, facial, and glossopharyngeal nerves.(1) Involvement of the trochlear nerve is considered rare or nonexistent.(1) In this report we present a case of upper eyelid retraction while looking in the field of action of the superior oblique muscle, indicating a primary superior oblique-levator muscle synkinesis..  

Tentorium cut completion is at the incisura posterior to the trochlear nerve.  

This approach did not endanger the trochlear nerve or any major midline venous structures in the quadrigeminal cistern.  

The compromised nerves were the oculomotor nerve in eight (72.7%), abducens nerve in two (18.2%) and trochlear nerve in one (9.1%).  

CMAP were bilaterally monitored from the inferior recti (for oculomotor function) and superior oblique (for trochlear nerve function) muscles.  

The following distances were measured from the porus trigeminus to: the internal acustic porus [ 6.6 (+/-1.7) mm], jugular foramen [ 16.2 (+/-1.8) mm], jugular tubercle [ 18.9 (+/-1.8) mm], abducent nerve [ 5.9 (+/-1.2) mm], trochlear nerve [ 4.6 (+/-1.4) mm], oculomotor nerve [ 8.4 (+/-1.9) mm], posterior clinoid process [ 14.7 (+/-1.8) mm] and median plane [ left 13.7 (+/-1.0), and right 13.5 (+/-1.9) mm].  

Nerve block caused a striking phase shift in the evoked response of right oculomotor and left trochlear nerves, in which (rightward) control responses were replaced by a smaller-amplitude response to leftward table motion.  

Subsequent genetic studies demonstrated that multiple axon types, including those of the spinal commissural neurons, are attracted to netrin in vivo; however, an in vivo role for netrin signaling in trochlear nerve repulsion has not been observed. Here, we demonstrate that mice with a null mutation in the netrin receptor Unc5c on the inbred C57BL/6J (B6) genetic background have ventral/ipsilateral trochlear nerve misprojections. Neither the trochlear nerve misprojections nor the phrenic nerve phenotype was observed in B6 embryos lacking the netrin receptors DCC or Neogenin1, or the ligand netrin1, indicating these signaling molecules are dispensable for guidance of these axons. Like the trochlear nerve, the phrenic nerve phenotype is modified in a B6 x SJL hybrid background.  

We present a patient with type 2 diabetes mellitus, arterial hypertension and hyperlipidaemia, who had simultaneous oculomotor and trochlear nerve palsies.  

Neuroimaging in both patients revealed pathological tortuosity of the basilar artery around the midbrain and displacement of the artery toward the side of the affected trochlear nerve.  

Oculomotor nerve injury occurred in 7 cases, 5 of which were transient, and trochlear nerve injury occurred in 1 case, all caused by inappropriate manipulations.  

The mean number of myelinated fibres was 8543.50 +/- 1231.85 being the unmyelinated 1402 +/- 241.58 in the oculomotor nerve; 1509 +/- 223.17 and 287.67 +/- 72.28 in the trochlear nerve and 2473.00 +/- 211.41 and 231.25 +/- 92.67 respectively in the abducent.  

OBJECTIVE AND IMPORTANCE: Schwannomas originating from the trochlear nerve without neurofibromatosis are extremely rare. CLINICAL PRESENTATION: A 42-year-old man presented with left hemiparesis and right trochlear nerve palsy. The tip of the trochlear nerve was fanned out and unified with the tumor. Only right trochlear nerve palsy has persisted. This report is the second case of intratumoral hemorrhage from a trochlear nerve schwannoma..  

The tent is incised behind the entrance of the trochlear nerve toward the superior petrosal sinus (SPS), which is coagulated and divided.  

METHODS: One of the most important parts of the exposure is to reflect the edge of the tentorium downward by 1 cm or more and to tether it with a suture placed lateral to or behind the insertion of the trochlear nerve and then to the dura mater of the floor of the middle fossa. Surgical forceps or a sharp dural hook are used to elevate the tentorial edge, in front of the trochlear nerve.  

Postoperative complications (18.6%) were evaluated, with one case of surgical wound infection, one case of hydrocephalus, one case of cerebrospinal fluid fistula, two cases of transient palsy of the trochlear nerve and one case of transient hemiparesis.  

We report the first case of trochlear nerve paresis as the inaugural neurological sign of PAN.  

Twenty-three patients with unilateral trochlear nerve palsy were measured in nine gaze positions.  

Four of them were with mononeuropathia multiplex and total ophthalmoplegia, affecting the oculomotor, trochlear and abducent nerves; 12 with paresis of the oculomotor nerve, one -- of the trochlear nerve and six -- of the abducent nerve.  

If an adaptive mechanism were acting to reduce the abnormal head posture, the head-tilt phenomenon should not be greater, and could even be smaller in bilateral than in unilateral superior oblique palsy, because in bilateral (symmetric) trochlear nerve palsies the vertical deviation at straight gaze is already small or absent without adaptation.  

In MR images of normal subjects, it is demonstrated that the oculomotor nerve, the trochlear nerve and the abducens nerve can be identified not only in the subarachnoid space and cavernous sinus, but also in the orbit.  

At the proximal site of the common tendinous ring, TH-positive fibers were found mainly in the abducent and trochlear nerves. At the distal site of this ring, TH-positive fibers were lost or markedly reduced in number in the abducent and trochlear nerves and were distributed mostly in the ophthalmic and oculomotor nerves.  

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.  

Magnetic resonance images with enhanced spoiled gradient recalled acquisition in the steady state (SPGR) and flow imaging using steady acquisition (FIESTA) disclosed a branch of the superior cerebellar artery lying on the root exit zone of the left trochlear nerve. A Teflon pad was placed between the compressing artery and the trochlear nerve.  

A case is reported where the onset of vertical diplopia secondary to a trochlear nerve palsy occurred as the presenting feature of polycythemia rubra vera. This may be the first report of an isolated trochlear nerve palsy secondary to polycythemia rubra vera and infarction of the fascicle or nerve..  

trochlear nerve neurinomas are very rare with less than 20 surgically proved cases reported in the literature. A case of histologically proved cystic trochlear nerve neurinoma, which was mimicking an intrinsic brainstem tumour is reported here.  

In separate animals, measurement of myelinated axon diameters with electron microscopy showed that approximately one-third of the myelinated axons in the nerves supplying the dura (nervus spinosus and tentorial nerves) could be classified as A-beta, since they were comparable in size to the majority of axons in the trochlear nerve and the upper end of the size range in the trigeminal nerve (i.e., > 5 microm)..  

Though diplopia occurred reportedly in about one fourth of SIH cases, trochlear nerve palsy has been reported only one case in the literature. After 15 days, he began to have diplopia caused by right trochlear nerve palsy. We suspected SIH for right trochlear nerve palsy, and he had symptomatic therapy. To say nothing of disturbance of consciousness and right hemiparesis, his trochlear nerve palsy was completely recovered after surgery at once.  

Recent research suggests it is caused by vascular compression of the trunk of the trochlear nerve.  

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 results showed that the nerves supplying the orbit included the optic nerve, oculomotor nerve, trochlear nerve, abducent nerve, the branches of ophthalmic nerve and the maxillary nerve.  

PURPOSE: To explain the positive Bielschowsky head-tilt (BHT) sign in unilateral trochlear nerve palsy (uTNP) by the kinematics of three-dimensional eye rotations.  

A patient developed an isolated trochlear nerve palsy after undergoing percutaneous trigeminal ganglion balloon compression for a second time. 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..  

A case of solitary and unilateral trochlear nerve palsy following a minor, blunt head impact is reported. This impact caused the midbrain concussion against the cerebellar tentorial notch resulting in a localized subarachnoid hemorrhage which caused the unilateral trochlear nerve palsy..  

RESULTS: The abducens nerve was consistently approximately one-third the length of the trochlear nerve at all ages that they studied.  

Patients with unilateral trochlear nerve palsy were oscillated about the nasooccipital (= roll) axis (+/-35 degrees, 0.3 Hz), and monocularly fixed on targets on a head-fixed Hess screen.  

We describe a patient presenting with trochlear nerve palsy and segmental sensory disturbance due to circumscribed mesencephalic hemorrhage. Neurological examination revealed left trochlear nerve palsy and segmental sensory disturbance of the left side almost above T11 level. Conversely, some reports have indicated that trochlear nerve palsy due to midbrain hemorrhage accompanies sensory disturbance contralateral to the lesion. The present case suggests that segmental sensory disturbance might accompany trochlear nerve palsy caused by hemorrhage of the inferior colliculus, as intramedullary fibers of the trochlear nerve and spinothalamic tract are located nearby and somatotopy of the spinothalamic tract is preserved even at the level of the midbrain..  

This study was conducted to determine whether PP is affected differently in patients with clinically diagnosed congenital (conTNP) and acquired (acqTNP) trochlear nerve palsy.  

The diplopia was caused by trochlear nerve palsy in every case. trochlear nerve function recovered completely in all patients within 3 to 6 months postoperatively. CONCLUSIONS: Postoperative diplopia following ATL occurs more often than previously thought and is primarily due to trochlear nerve dysfunction.  

In a patient with superior oblique myokymia, a contact is visualised between the right trochlear nerve and a vascular structure by high resolution thin slices magnetic resonance images coupled to angio-MR.  

OBJECTIVE: To anatomically reconstruct the oculomotor nerve, trochlear nerve, and abducent nerve by skull base surgery. METHODS: Seventeen cranial nerves (three oculomotor nerves, eight trochlear nerves and six abducent nerves) were injured and anatomically reconstructed in thirteen skull base operations during a period from 1994 to 2000. During a follow-up period of 4 months to 6 years, complete recovery of function was observed in 6 trochlear nerves (75%) and 4 abducent nerves (67%), while partial functional recovery was observed in the other cranial nerves including 2 trochlear nerves, 2 abducent nerves, and 3 oculomotor nerves.  

trochlear nerve schwannoma is an extremely rare intracranial tumour. Early investigation of patients with unexplained trochlear nerve palsy by MRI will facilitate the management of these rare tumours..  

The tumor arising from the right trochlear nerve was seen excavating into the hippocampus and the left vestibular nerve into the medulla.  

Moreover, progress in neuroimaging technology has implicated neurovascular contact of the trochlear nerve in instances of superior oblique myokimia.  

Retractors are then placed, and the tentorium is visualized and opened laterally, avoiding the trochlear nerve.  

OBJECTIVE: To describe the anatomy of the cisternal segment of the trochlear nerve as seen through different neurosurgical approaches. METHODS: The cisternal course of ten trochlear nerves was observed in five cadaveric embalmed heads, through the view afforded by the median infratentorial-supracerebellar, the extreme-lateral infratentorial-supracerebellar, and the combined presigmoid-subtemporal transtentorial approaches. The relationships of the trochlear nerve with the surrounding neuro-vascular structures were analyzed. RESULTS: We identified 3 segments of the cisternal trochlear nerve: quadrigeminal, ambient and tentorial. CONCLUSION: The trochlear nerve is a very delicate structure that can be easily injured during approaches to the tentorial incisura.  

Units that responded during rotation were located in lateral and medial PBN and KF caudal to the trochlear nerve at sites that were confirmed anatomically to receive superior vestibular nucleus afferents.  

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