Extracranial transport of brain lymphatics via cranial nerve in human

Extracranial waste transport from the brain interstitial fluid to the deep cervical lymph node (dCLN) is not extensively understood. The present study aims to show the cranial nerves that have a role in the transport of brain lymphatics vessels (LVs), their localization, diameter, and number using podoplanin (PDPN) and CD31 immunohistochemistry (IHC) and Western blotting. Cranial nerve samples from 6 human cases (3 cadavers, and 3 autopsies) were evaluated for IHC and 3 autopsies for Western blotting. The IHC staining showed LVs along the optic, olfactory, oculomotor, trigeminal, facial, glossopharyngeal, accessory, and vagus nerves. However, no LVs present along the trochlear, abducens, vestibulocochlear, and hypoglossal nerves. The LVs were predominantly localized at the endoneurium of the cranial nerve that has motor components, and LVs in the cranial nerves that had sensory components were present in all 3 layers. The number of LVs accompanying the olfactory, optic, and trigeminal nerves was classified as numerous; oculomotor, glossopharyngeal, vagus, and accessory was moderate; and facial nerves was few. The largest diameter of LVs was in the epineurium and the smallest one was in the endoneurium. The majority of Western blotting results correlated with the IHC. The present findings suggest that specific cranial nerves with variable quantities provide a pathway for the transport of wastes from the brain to dCLN. Thus, the knowledge of the transport of brain lymphatics along cranial nerves may help understand the pathophysiology of various neurological diseases.

Microanatomy of the central myelin portion and transitional zone of the oculomotor and abducens nerves

BACKGROUND

The microanatomy of the central myelin portion and transitional zone of several cranial nerves including trigeminal, facial, vestibulocochlear, glossopharyngeal, and vagus nerves have been clearly demonstrated to provide information for neurovascular compression syndrome such as trigeminal neuralgia and hemifacial spasm. However, the study of oculomotor and abducens nerve is limited.

MATERIALS AND METHODS

Oculomotor and abducens nerves were harvested with a portion of brainstem and embedded in paraffin. Longitudinal and serial sections from ten of each cranial nerve were stained and a photomicrograph was taken to make the following observations and measurements: 1) patterns of central myelin portion, 2) length of central myelin portion, and 3) depth of central myelin- peripheral myelin transitional zone.

RESULTS

For oculomotor nerve, the longest central myelin bundle was always seen on the first nerve bundle and that the length of central myelin decreased gradually. For abducens nerve, morphological patterns were classified into four types based on number of nerve rootlets emerging from the brainstem and number of nerve bundles in each rootlet. Length of central myelin portion was between 0.36-6.10 mm (2.75 ± 0.83 mm) and 0.13-5.01 mm (1.66 ± 1.39 mm) for oculomotor and abducens nerves, respectively. The oculomotor nerve transitional zone depth was 0.07-058 mm (0.23 ± 0.07 mm), while for abducens nerve, depth was 0.05-0.40 mm (0.16 ± 0.07 mm). Positive weak correlations between central myelin and depth of TZ were found in oculomotor nerve (r +0.310, p < 0.05) and abducens nerves (r +0.413, p < 0.05).

CONCLUSIONS

Detailed microanatomy of the central myelin and transitional zone might be beneficial for locating the site of compression in neurovascular conflicts at oculomotor and abducens nerves.

Sphenoid sinus cholesterol granulomas presenting with abducens nerve palsy

We discuss two patients who presented with sphenoid sinus cholesterol granulomas and associated unilateral abducens nerve palsies. Two case reports from our institution are reported. A literature review of available articles is presented, discussing both cholesterol granulomas of the sphenoid sinus and sphenoid sinus lesions that present with unilateral abducens palsy. A total of nine cases of sphenoid sinus cholesterol granulomas have been previously reported in the literature. A wide variety of sphenoid sinus pathologies can present with unilateral abducens nerve palsies, however no sphenoid sinus cholesterol granulomas with this presentation were found in the literature. In conclusion, cholesterol granulomas should be included in the differential when a patient presents with an expansile mass of the sphenoid sinus and associated unilateral abducens nerve palsy.

The Immediate Onset of Isolated and Unilateral Abducens Nerve Palsy Associated with COVID-19 Infection: A Case Report and Literature Review

Cranial nerve palsy associated with coronavirus disease 2019 (COVID-19) is rare. We herein report the first Asian case of the immediate onset of isolated and unilateral abducens nerve palsy (ANP) accompanied with COVID-19 infection. A 25-year-old man developed diplopia one day after the COVID-19 symptom onset. Neurological examination revealed limitation of left eye abduction without ataxia and hyporeflexia. Negative anti-ganglioside antibody results and mild albuminocytological dissociation were noted. The patient was diagnosed with left ANP accompanied by COVID-19 infection. The ANP spontaneously recovered without treatment. ANP can develop during the early phase of COVID-19 infection and adversely affect patients' quality of life.

Motor neurons loss in Parkinson Disease: An electrophysiological study (MUNE)

The aim of this study was to evaluate the involvement of a peripheral motor neuron in Parkinson Disease (PD) using the motor unit number estimation (MUNE) method, which reflects motor unit loss in motor neuron diseases. Multipoint incremental MUNE method was calculated in abductor pollicis brevis (APB) and abductor digiti minimi (ADM) in forty one (41) patients with PD and forty five (45) healthy volunteers. From the analysis, the MUNE of APB was lower in PD than in the control group, especially in the sub-group aged 60 years or older. MUNE was negatively correlated with the age of patientsfor APB, but not with the duration of the disease and advancement of PD. The loss of motor units in sporadic Parkinson's disease revealed by multipoint incremental MUNE method is considered a sign of lower motor neuron involvement, however, loss of motor neurons is slight and does not manifest equally in all muscles . Thus, the results from this experiment should be treated with concern, as it could be a landmark for further experiments.

Transmitter and ion channel profiles of neurons in the primate abducens and trochlear nuclei

Extraocular motoneurons initiate dynamically different eye movements, including saccades, smooth pursuit and vestibulo-ocular reflexes. These motoneurons subdivide into two main types based on the structure of the neuro-muscular interface: motoneurons of singly-innervated (SIF), and motoneurons of multiply-innervated muscle fibers (MIF). SIF motoneurons are thought to provoke strong and brief/fast muscle contractions, whereas MIF motoneurons initiate prolonged, slow contractions. While relevant for adequate functionality, transmitter and ion channel profiles associated with the morpho-physiological differences between these motoneuron types, have not been elucidated so far. This prompted us to investigate the expression of voltage-gated potassium, sodium and calcium ion channels (Kv1.1, Kv3.1b, Nav1.6, Cav3.1-3.3, KCC2), the transmitter profiles of their presynaptic terminals (vGlut1 and 2, GlyT2 and GAD) and transmitter receptors (GluR2/3, NMDAR1, GlyR1α) using immunohistochemical analyses of abducens and trochlear motoneurons and of abducens internuclear neurons (INTs) in macaque monkeys. The main findings were: (1) MIF and SIF motoneurons express unique voltage-gated ion channel profiles, respectively, likely accounting for differences in intrinsic membrane properties. (2) Presynaptic glutamatergic synapses utilize vGlut2, but not vGlut1. (3) Trochlear motoneurons receive GABAergic inputs, abducens neurons receive both GABAergic and glycinergic inputs. (4) Synaptic densities differ between MIF and SIF motoneurons, with MIF motoneurons receiving fewer terminals. (5) Glutamatergic receptor subtypes differ between MIF and SIF motoneurons. While NMDAR1 is intensely expressed in INTs, MIF motoneurons lack this receptor subtype entirely. The obtained cell-type-specific transmitter and conductance profiles illuminate the structural substrates responsible for differential contributions of neurons in the abducens and trochlear nuclei to eye movements.

An Oculopharyngeal Subtype of Guillain-Barré Syndrome Sparing the Trochlear and Abducens Nerves

Guillain-Barré syndrome (GBS) comprises a group of polyneuropathies characterized by rapid progression of limb paralysis. Various subtypes of GBS have been reported. The oculopharyngeal subtype of GBS is currently understood to be primarily a cranial polyneuropathy without limb weakness or cerebellar ataxia. In our case of 62-year-old man, gastrointestinal infection was followed by paranesthesia of the hands. He had bilateral ptosis, pharyngeal disorder, and tongue and bifacial weakness. We diagnosed oculopharyngeal subtype of GBS. It responded to intravenous immunoglobulin. This case highlights the need for further characterization of unusual GBS subtypes.

Herpes zoster involving the abducens and vagus nerves without typical skin rash: A case report and literature review

RATIONALE

Herpes zoster is characterized by unilateral vesicular eruption and it most often affects the trigeminal nerve. We would like to report a rare case of abducens and vagus nerves palsy caused by varicella zoster virus (VZV) without the typical vesicular rash.

PATIENT CONCERNS

A 71-year-old woman presented with diplopia. Three days previously, she had experienced sore throat and hoarseness.

DIAGNOSIS

At presentation, the prism cover test revealed esotropia of 10 prism diopters at primary gaze, and abduction was restricted in the right eye. No vesicular rash was observed on the patient's face, and magnetic resonance imaging of the brain showed no pathology. Flexible fiberoptic laryngoscopy revealed multiple ulcerations on the right side of the larynx-from the epiglottis to the arytenoid. After 1 day of hospitalization, a diffuse skin rash occurred on the patient's trunk, and polymerase chain reaction for VZV DNA was positive at the skin lesion. The patient was diagnosed as having herpes zoster associated with vagus and sixth nerve palsy.

INTERVENTION AND OUTCOMES

She received famciclovir at a dose of 500 mg 3 times daily for 7 days and coadministered methylprednisolone. At the 4-month follow-up, her diplopia and eye movement had resolved completely.

LESSONS

In patients with abducens nerve palsy without typical vesicular lesion, herpes zoster may not be detected early. In that case, systemic examination is very important for diagnosing herpes zoster.

Papilloedema and Cranial Nerve Palsies Complicating Apparent Benign Aseptic Meningitis

Three patients who presented with apparently uncomplicated aseptic meningitis subsequently developed papilloedema and sixth cranial nerve palsies between 11 and 16 days after the onset of the illness. All three patients recovered completely without treatment. Raised intracranial pressure is a poorly recognized complication of aseptic meningitis that may represent a post-infective or 'allergic' response to an enteroviral infection. While clinicians should be aware of this possible complication of aseptic meningitis, differentiation from tuberculous meningitis may be difficult necessitating empirical treatment with anti-TB drugs.

[Pseudo abducens palsy]

In this study, we present two cases of different eye movement disorders with variable case histories but with the same end stage; abduction paresis of one of the eyes, which ceased when the other eye was covered. Our differential diagnosis is that either the ocular form of myasthenia gravis, convergence spasm or ocular myotonia could explain the symptoms. However, we hypothesize that the clinical picture corresponds to pseudo abducens palsy or focal dystonia of the extraocular muscle, which in turn could be the result of impaired inhibition of the tonic resting activity of the antagonistic medial rectus muscle. We offer an explanation for the patomechanism of pseudoabducens palsy and the variants of internuclear ophthalmoplegia.

Horner syndrome and VI nerve paresis as a diagnostic clue to a hidden lesion

A 33-year-old man treated elsewhere for an isolated VI cranial nerve paresis underwent an attempted transnasal biopsy of a large space-occupying lesion in the cavernous sinus and petrous apex seen on a CT scan. During the procedure, he developed severe bleeding and hypovolaemic shock. When he came to us 2 years later, he had Homer syndrome along with a mild VI nerve paresis that aided in localizing the lesion to the carotid canal and the posterior cavernous sinus. Digital subtraction angiography revealed a large internal carotid artery aneurysm of the laceral and petrous segments within the carotid canal, mushrooming into the posterior cavernous sinus.

Abducens Nerve Ocular Neuromyotonia Following Non-sellar or Parasellar Tumors

Ocular neuromyotonia is an uncommon disorder resulting from episodic involuntary discharge of ocular motor nerves producing sustained contraction of their respective ocular muscles. Ocular neuromyotonia manifests in brief spells of diplopia occurring spontaneously or after eccentric gaze holding. In most cases, ocular neuromyotonia follows months or years after radiotherapy to the sellar and parasellar region and involves the oculomotor nerve. We report two unusual cases of abducens nerve ocular neuromyotonia that followed radiation therapy of tumors in areas other than the sellar or parasellar region.

[Clinical observation on Chinese drug acupoint-injection for treatment of acquired abducent paralysis]

OBJECTIVE

To seek for an effective therapy for abducent paralysis.

METHODS

Seventy-six cases of abducent paralysis were randomly divided into an acupoint-injection group and a western medicine group. The acupoint-injection group were treated by point-injection therapy, with Jingming (BL 1), Yangbai (GB 14), Sibai (ST 2), Tongziliao (GB 1) on the affected side, and bilateral Ganshu (BL 18) used as basic points and compound Danggui Injection as the principal injected medicine, and in combination with corresponding acupoints and injected medicine according to different syndrome types. The western medicine group were treated with routine western medicine therapy. After treatment for 36 days, the therapeutic effects were recorded and analyzed statistically.

RESULTS

The total effective rate was 94.7% in the acupoint-injection group and 76.3% in the western medicine group with a significant difference between the two groups (P < 0.05); there was a significant difference between the two groups in eyeball moving rate and restoration of cateral rectus (P < 0.05).

CONCLUSION

Chinese drug acupoint-injection therapy has a definite therapeutic effect on acquired abducent paralysis, which is better than that of routine western medicine.

Bilateral intracavernous carotid artery aneurysms presenting as progressive cranial nerve palsies

Bilateral intracavernous carotid artery aneurysms are rare and can present with different clinical findings. We report such a case presenting with progressive cranial nerve palsies due to gradual increase in the size of aneurysms. This case demonstrates the clinician's difficulty in diagnosis when isolated cranial nerve palsy is the sole presenting sign.

Isolated ocular motor nerve palsy in dural carotid-cavernous sinus fistula

The incidence of dural carotid-cavernous sinus fistula (DCCF) presenting as isolated ocular motor nerve palsies without congestive ocular features is unknown. We reviewed the DCCF patients in our hospital during the last 10 years to elucidate the clinical and neuroradiological features of DCCF with isolated ocular motor nerve palsy. Eleven amongst the 33 DCCF patients presented isolated ocular motor nerve palsy. All the 11 patients underwent brain CT/CT angiography (CTA) and/or MRI/MR angiography (MRA), before the digital subtraction angiography (DSA). The compromised nerves were the oculomotor nerve in eight (72.7%), abducens nerve in two (18.2%) and trochlear nerve in one (9.1%). Brain CT and/or CTA were conducted in four patients but all unremarkable. MRI and/or MRA were performed in nine patients and six of them showed compatible findings of DCCF. The diagnoses of DCCFs were confirmed by DSA and all were posterior-draining type. The outcome was good, with a total recovery rate of 54.5% within 12 months. Thirty-three percent (11 of 33) of our DCCF patients presented with isolated ocular motor nerve palsy, which is not uncommon. MRI and MRA are of value in the initial evaluation, but DSA is necessary for the accurate diagnosis and treatment planning.

Solitary Fibrous Tumor Arising from Cranial Nerve VI in the Prepontine Cistern: Case Report and Review of a Tumor Subpopulation Mimicking Schwannoma

OBJECTIVE:

The authors present a report of a solitary fibrous tumor (SFT) arising from the intradural component of the VIth cranial nerve as it travels through the prepontine cistern. SFTs of the central nervous system are extremely rare entities that clinically masquerade as dural-based lesions, such as meningiomas or hemangiopericytomas. Because of their infrequency and clinical similarity to other central nervous system (CNS) lesions, diagnosis is largely dependent on pathological features. In this study, the authors define a subpopulation of SFTs that seem to arise directly from nerve, rather than meninges, and clinically mimic the appearance of a schwannoma.

CLINICAL PRESENTATION:

The patient was a 29-year-old woman with a several-month history of progressive right arm and leg numbness and mild hemiparesis, with the development of diplopia 2 weeks before admission. Outside imaging revealed a 3.9-cm mass in the prepontine cistern with extension into Meckel's cave and the cavernous sinus, resulting in significant brainstem compression.

INTERVENTION:

The patient underwent preoperative angiography with embolization of feeding vessels off of the left meningohypophyseal trunk. The patient was then taken to the operating room by a combined neurosurgical and ear, nose, and throat team, where the patient underwent a retrolabyrinthine/subtemporal craniotomy for tumor resection. During resection of the prepontine component, the tumor was identified as originating from the left Cranial Nerve VI as it traversed through the prepontine cistern. Resection of the tumor component involving the cavernous sinus and Meckel's cave was deferred for follow-up treatment with intensity-modulated radiation therapy. Pathological examination revealed tissue consistent with the diagnosis of SFT.

CONCLUSION:

SFTs involving the CNS are rare entities that are almost always diagnosed after tissue is obtained because of their clinical and radiographic similarity to meningiomas. This patient had an SFT masquerading as a VIth cranial nerve schwannoma. Although the natural history of SFTs in the CNS is not completely understood, correct diagnosis is important, given the rate of recurrence found in the more common pleural-based SFT and examples of CNS SFTs with malignant features.

Ocular complications of sigmoid sinus thrombosis from L-asparaginase

This article presents a 9-year-old boy with acute lymphocytic leukemia who developed ocular complications after beginning treatment with L-asparaginase. Ocular motor examination revealed esotropia with a right abduction deficit, consistent with a sixth nerve palsy, and funduscopy revealed bilateral optic disc edema. Thrombosis of the right sigmoid sinus was noted on magnetic resonance imaging and magnetic resonance venography. Symptoms gradually resolved after discontinuing L-asparaginase and treatment with heparin.

Effects of electrode penetrations into the abducens nucleus of the monkey: eye movement recordings and histopathological evaluation of the nuclei and lateral rectus muscles

Two adult rhesus monkeys that had undergone 2 years of electrode penetrations into their abducens and vestibular nuclei, for chronic eye movement studies, were examined histologically. An analysis of their VIth nucleus neurons and lateral rectus muscles revealed the following. Twenty-two percent of the large neurons (approximately 30 microm in diameter), on average, were missing and extensive neuropil disruption and gliosis was evident in the experimental side abducens nuclei as compared with the control side in each animal. While the lateral rectus muscles showed small, but inconsistent, changes in total fiber number, the muscle fiber diameters were altered, leading to a more homogenous muscle and making the typical orbital and global subdivisions of the muscle less distinct. Eye movement records from before and after the electrophysiological studies were comparable. We discuss how the complex architecture of the extraocular muscles as well as the possibility of polyneuronal innervation of single muscle fibers could explain our results.

Botulinum toxin and the eye

Botulinum toxin in ophthalmology is used to reduce the function of the eyelid muscles in spasms or therapeutically. Therapeutic and diagnostic use in strabismus is also discussed, along with the controversial treatment of nystagmus.

[Botulinum toxin A in treatment of the sixth cranial nerve palsy]

OBJECTIVE

To study the methods and the effects of botulinum toxin A (BTXA) in the treatment of paralytic esotropia (PE) due to the sixth cranial nerve palsy.

METHODS

BTXA was injected into the extra-ocular muscles of 89 patients with PE. The number of injections was 1 to 5, in average 1.5. Of them, 27 patients received injections combining with surgeries at the same time, and 16 received surgeries after injections for 3 to 28 months. The procedures include recession-resection (or combining with myectomy), Jenson procedure, or vertical muscle transposition.

RESULTS

Of the patients having received injections alone, 35 restored orthotropia and binocular single vision after 1 to 4 injections. Eleven patients restored to orthotropia after the injection and surgery at the second stage, and the mean correction of the strabismus degree was 42.7( triangle up ) +/- 32.2( triangle up ). Fourteen cases in the simultaneous surgical and injection group restored orthotropia after the surgery, and the mean correction of the strabismus degree was 90.0( triangle up ) +/- 40.1( triangle up ). Of them, 14 restored binocular single fusion and their range of visual fixation expanded to 20 degrees - 70 degrees.

CONCLUSIONS

BTXA injected into extra-ocular muscles is an ideal therapy for the treatment of PE. Injection of BTXA during the first 6 months after the onset as a preoperative therapy may alleviate medial rectus restriction and promote the recovery of the lateral rectus functions. Some patients may restore orthotropia by injection alone. Patients under-corrected at six months after onset can be treated with surgery. Injection combined with surgery at the same time may preserve the function of medial rectus, avoid performing operation on more than two rectus, prevent the risk of anterior segment ischemia in surgery of multiple muscles and expand the field of binocular single vision as large as possible.

In vitro eye-blink classical conditioning is NMDA receptor dependent and involves redistribution of AMPA receptor subunit GluR4

The classically conditioned vertebrate eye-blink response is a model in which to study neuronal mechanisms of learning and memory. A neural correlate of this response recorded in the abducens nerve can be conditioned entirely in vitro using an isolated brainstem-cerebellum preparation from the turtle by pairing trigeminal and auditory nerve stimulation. Here it is reported that conditioning requires that the paired stimuli occur within a narrow temporal window of <100 msec and that it is blocked by the NMDA receptor antagonist d,l-2-amino-5-phosphonovaleric acid. Moreover, there is a significant positive correlation between the levels of conditioning and greater immunoreactivity with the glutamate receptor 4 (GluR4) AMPA receptor subunit in the abducens motor nuclei, but not with NMDAR1 or GluR1. It is concluded that in vitro classical conditioning of an abducens nerve eye-blink response is generated by NMDA receptor-mediated mechanisms that may act to modify the AMPA receptor by increasing GluR4 subunits in auditory nerve synapses.

[Speech disorders in Alajouanine syndrome]

Alajouanine syndrome includes congenital, bilateral, central facial and abducens nerves palsy and clubfoot. The authors present speech disorders and helpful influence of early rehabilitation.

Unusual cranial nerve palsy caused by cavernous sinus aneurysms. Clinical and anatomical considerations reviewed

BACKGROUND

Two cases of intracavernous internal carotid artery aneurysm with unusual clinical findings are reported. The pathomechanism and clinical significance are discussed.

CASE DESCRIPTION

The first patient was a 49-year-old woman who presented with 6th nerve palsy and Horner's syndrome caused by a posteriorly located intracavernous aneurysm. The symptoms improved gradually in proportion to the size of the aneurysm. The second patient was a 69-year-old woman with isolated oculomotor superior division palsy caused by an anteriorly located large aneurysm.

CONCLUSION

In the first case, a local aneurysmal compression at both the 6th nerve and the sympathetic fibers sent from the plexus on the intracavernous internal carotid artery is the most probable explanation. In the second case, the aneurysm might have selectively compressed the superior division of the oculomotor nerve at the anterior cavernous sinus. Clinical recognition of these syndromes results in a better diagnostic orientation. The authors discuss the pertinent anatomy and pathophysiology of the lesions because these findings are rarely seen clinically or in the literature.

Stereotactic radiosurgery for cavernous sinus cavernous hemangioma--case report

A 40-year-old female presented with cavernous sinus cavernous hemangioma manifesting as left abducens and trigeminal nerve pareses. Magnetic resonance imaging revealed a left cavernous sinus tumor. The tumor was partially removed. Histological examination of the specimen confirmed cavernous hemangioma. Radiosurgery was performed using the gamma knife. The tumor markedly decreased in size after radiosurgery and morbidity was avoided. Cavernous sinus cavernous hemangiomas may be difficult to treat surgically due to intraoperative bleeding and cranial nerve injury. Stereotactic radiosurgery can be used either as an adjunct treatment to craniotomy, or as the primary treatment for small cavernous sinus cavernous hemangioma.

Abducens nerve palsy complicating pregnancy: a case report

We report a case presented at 38 weeks gestation with abducens nerve palsy. No specific pathology was found. After reviewing all the previously reported cases, hypertension is found to be a common factor in all cases presenting in late pregnancy. The clinical course is benign and all resolved after delivery.

Pediatric third, fourth, and sixth nerve palsies: a population-based study

PURPOSE

To determine the population-based incidence and cause of cranial nerve palsies affecting ocular motility in children in the circumscribed population of Olmsted County, Minnesota.

METHODS

The Rochester Epidemiology Project medical records linkage system captures virtually all medical care provided to Olmsted County residents. By means of this database, all cases of third, fourth, and sixth cranial nerve palsy were identified among county residents less than 18 years of age from 1978 through 1992. Medical records were reviewed to confirm the diagnosis, determine the cause, and document county residency. Incidence rates were adjusted to the age and sex distribution of the 1990 white population in the United States.

RESULTS

Over this 15-year period, 36 incidence cases of cranial nerve palsy were identified in 35 children in this defined population. The age-adjusted and sex-adjusted annual incidence of third, fourth, and sixth nerve palsies combined was 7.6 per 100,000 (95% confidence interval, 5.1 to 10.1). The most commonly affected nerve was the fourth (36%), followed by the sixth (33%), the third (22%), and multiple nerve palsies (9%). The most common cause was congenital for third and fourth nerve palsy, undetermined for sixth, and trauma for multiple nerve palsies. Although three cases were associated with neoplasia, a cranial nerve palsy was not present at the time of diagnosis in any case.

CONCLUSIONS

Unlike many institutionally based referral series, our population-based study provides data on the incidence and cause of third, fourth, and sixth nerve palsies in a geographically defined population. In contrast to previous institutionally based series, nearly half the cases were congenital in origin, and in no case did intracranial neoplasia present as an isolated nerve palsy.

[A case of Ramsay Hunt syndrome associated with local meningitis, multiple cranial neuropathy, and the second cervical nerve involvement]

A 76-year-old man with herpetic vesicle in the right auricle developed ipsilateral 5th, 6th, 7th, and 8th cranial nerves involvement and pain in the dermatome of the second cervical nerve. The CSF study revealed elevated opening pressure up to 220 mmH2O, and pleocytosis up to 151 cells/mm3. Ninety-nine percent of the CSF cells were mononuclear cells. CSF protein was 47 mg/dl, and CSF glucose was 62 mg/dl. On the 24th hospital day the CSF cells decreased to 13/mm3 with 100% mononuclear cells. Titer of varicella-zoster virus (VZV) antibody was significantly elevated in CSF. Brain MRI and ABR demonstrated no abnormality. Although disorders of 5th and 6th cranial nerves and second cervical nerve improved, mild facial nerve palsy lasted and hearing disturbance showed no recovery. There are only seven cases of Ramsay Hunt syndrome associated with external ophthalmoplegia in the literature. However, un like the present case, none of these cases presented disorders of upper cervical nerves. In this case, we speculate that spreading of reactivated VZV caused local meningitis and multiple cranial nerve involvement as well as the second cervical nerve.

[A rare case of trapped fourth ventricle: an unique symptom appeared after fourth ventriculo-peritoneal shunting]

We experienced a unique case of trapped fourth ventricle after shunting for post-meningitic hydrocephalus. A five-year-old infant was diagnosed as meningitis shortly after his birth, and secondarily suffered from hydrocephalus. He underwent lateral-ventriculo-peritoneal shunting, fourth-ventriculo-cisterna-magna shunting and so on, but bilateral abducens palsy appeared. The following head CT and MRI revealed "trapped fourth ventricle". Though there are several case reports of trapped fourth ventricle with abducens palsy, most of them followed enlargement of the fourth ventricle; nevertheless in our case, abducens palsy appeared when the fourth ventricle reduced in size and the symptom vanished when it enlarged. We thought that a traction force to the abducens nerve had occurred also in the condition of reduced fourth ventricle size, because there would have been a dense adhesion after meningitis in his subarachnoidal space. We tried to improve his symptom in one way or another by keeping the fourth ventricle in appropriate volume. His abducens palsy was controlled by switching the on-off valve between forth ventricle and peritoneum. We expect that a higher-pressure programmable shunt valve or a lower-flow-regulating shunt system be invented in order to cope with the cases like ours.

[Treatment of paralytic esotropia by botulinum type A toxin]

PURPOSE

The purpose of the present paper is to evaluate the therapeutic effect of a single injection of 2.5 U of botulinum Type A Toxin for paralytic esotropia resulting from unilateral abducens palsy.

MATERIAL

Patients were divided into 3 groups: acute group of 7 patients 3 to 4 months after onset, chronic group of 6 patients 5 to 11 months after onset, and a protracted group of 7 patients more than one year after onset. Patients less than 3 months after onset were excluded because of possible spontaneous recovery.

RESULTS

The amount of ocular deviation averaged 39.2 delta before and 16.3 delta after treatment. Following treatment, good motility and alignment were obtained in 10 patients, including 5 cases in the acute group, 4 in the chronic group, and 1 in the protracted group. The reduction of deviation averaged 82%, 74%, and 34% in the acute, chronic, and protracted groups, respectively. The therapeutic effect was also related to the degree of contracture of the medial rectus muscle. Six cases that failed to respond to the current therapy underwent surgery for recession/advancement of the horizontal muscles. The surgical outcome was not related to the maximum reduction obtained by injection of botulinum toxin.

CONCLUSION

We conclude that the injection should be administered at the end of 3 months after onset, if the deviation has not shown any improvement by then. It may be effective in chronic cases. Not much improvement can be expected if the condition has persisted for one year or longer.

Magnetic resonance imaging after surgical transposition defines the anteroposterior location of the rectus muscle pulleys

INTRODUCTION

Connective tissue pulleys serve as the functional origins of the rectus extraocular muscles (EOMs) and constrain the sideslip of the posterior EOM bellies after transposition surgery. Anterior to the pulleys, EOM paths appreciably displace to reach their transposed insertions. The inflection points in the EOM paths from minimal posterior displacement to maximal anterior displacement should define the anteroposterior location of the EOM pulleys after transposition.

METHODS

Contiguous cross-sectional magnetic resonance images were obtained in planes perpendicular to the long axis of the orbit over its entire anteroposterior extent before and after operation in 6 patients who underwent rectus muscle transposition surgery. Four patients underwent full tendon width transposition of the vertical rectus muscles laterally for lateral rectus palsy. Two of these patients had augmentation of the transposition with sutures that fixated the temporal margins of the transposed muscles posteriorly to the sclera adjacent to the borders of the lateral rectus muscle. One patient underwent full tendon width transposition of the horizontal rectus muscles superiorly for superior rectus palsy. One patient underwent full tendon width transposition of both lateral rectus muscles inferiorly for "A" pattern esotropia. Paths of EOMs were defined relative to the area centroid of the orbit. Pulley locations were inferred from EOM paths. The postoperative change in EOM pulley location was obtained by subtracting the preoperative pulley location from the postoperative pulley location for each image plane.

RESULTS

For all patients, the postoperative change in EOM belly location was relatively small posterior to the globe-optic nerve junction. The 2 patients with abducens palsy who underwent placement of posterior augmentation sutures, however, demonstrated a significantly larger displacement of the posterior vertical rectus paths compared with similar patients who did not receive augmentation sutures. For all horizontally transposed vertical rectus muscles and inferiorly transposed lateral rectus muscles, the inflection of the EOM path began 3 mm anterior to the globe-optic nerve junction. For the superiorly transposed medial rectus muscle and lateral rectus muscle, the inflection began 6 mm anterior to the globe-optic nerve junction.

CONCLUSIONS

The anteroposterior locations of the EOM pulleys can be defined by analysis of EOM displacement after transposition surgery. Augmentation of transpositions by posterior suturing displaces the EOM pulleys substantially more than nonaugmented transpositions.

[Four cases of abducens palsy caused by a vascular lesion of the vertebrobasilar system]

Several pathological conditions are responsible for abducens palsy, but a lesion of the vertebral artery (VA) has rarely been recognized as one of the causes. It has been reported that a high percentage of cases of abducens palsy are involved with ruptured dissecting aneurysms of the VA. We investigate the vertebrobasilar anatomy in 4 patients, suffering with abducens palsy. One patient revealed a fusiform dilatation of the vertebral artery on the same side as the abducens palsy. Three patients were noted to have stenosis of the vertebral artery from the origin of the posterior inferior cerebellar artery (PICA) to the union. Finally, four patients were found to have abnormal vertebrobasilar anatomy, which was on the same side as the abducens palsy. It is conceivable that changes of vertebrobasilar circulation may cause abducens palsy through direct compression, or ischemic events.

Peripheral-type primitive neuroectodermal tumor arising in the tentorium. Case report

The authors report the case of a peripheral primitive neuroectodermal tumor (PNET) arising in the tentorium in a 5-year-old boy who presented with frequent vomiting and mild palsy of the left abducent nerve. Following complete surgical excision of the tumor via a transpetrosal approach, the patient has thus far been disease free for 7 years. The tumor tissue was composed of small cells with uniform round nuclei and minimal identifiable cytoplasm. Homer-Wright rosettes were frequently observed. Immunohistochemical studies demonstrated a positive reaction to HBA-71, which recognizes the cell surface glycoprotein p30/32, a product of the MIC2 gene. Both the clinical and immunohistochemical characteristics of this tumor are consistent with a diagnosis of peripheral PNET, which is genetically distinct from the more common intracranial PNET.

A practice pathway for the initial diagnostic evaluation of isolated sixth cranial nerve palsies

PURPOSE

To define a practice pathway for the evaluation of sixth-nerve palsies (SNPs) and to determine its cost-effectiveness and validity in a retrospective chart review.

METHODS

A Medline search of the English-language literature from 1966 to 1995 was performed to define the available clinical evidence and develop the practice pathway. The authors retrospectively reviewed 407 charts with the diagnosis of SNP seen at three centers. Information obtained included: etiologic diagnosis if known; development of new neurologic or ophthalmologic findings; and results and costs of neuroimaging studies, if performed.

RESULTS

Of the 407 patients, 98 underwent computed tomography scans and 212 underwent magnetic resonance imaging of the head. Eighty cases were non-isolated, 317 were isolated SNP, and ten could not be classified from chart information. Of the 317 cases of isolated SNP, 49 were classified as traumatic; 5, congenital; 158, vasculopathic; 63, nonvasculopathic; and 42, progressive or unresolved. Following the recommendations of the practice pathway, the 158 patients classified as having vasculopathic SNP would not have undergone neuroimaging studies, realizing a savings of $100,000 in this study population of 407 patients.

CONCLUSION

The recommendations of the practice pathway are supported by review of the literature and the retrospective review of these cases. However, a prospective study with a matched control group is needed to demonstrate regional and specialty-specific variations in care and to strengthen the clinical certainty of the pathway recommendations.