Resolution of optic nerve edema and improved visual function after optic nerve sheath fenestration in a patient with osteopetrosis

Update on the application of optic nerve sheath fenestration

BACKGROUND

With the ongoing development of surgical procedures and instruments, the safety of optic nerve sheath fenestration (ONSF) has been improved.

OBJECTIVE

Through the past three decades, progress has been made in preventing visual loss from chronic optic nerve swelling in idiopathic intracranial hypertension (IIH), secondary intracranial hypertension and local optic nerve diseases. We now review the updated application of ONSF in those diseases.

METHODS

The application of ONSF in papilledema due to IIH, secondary intracranial hypertension to cerebral venous sinus occlusion, Cryptococcal meningitis, and intracranial mass or tumors is reviewed. Additionally, the potential benefits of ONSF in local optic neuropathy from optic nerve sheath meningioma, optic nerve drusen, traumatic optic neuropathy and optic nerve/sheath biopsy are also described.

RESULTS

Although ONSF has little or no effect on intracranial pressure, it is a safe, relative easy and effective surgical procedure to prevent or reverse visual loss in IIH. When other treatment modalities fail to timely protect vision, ONSF can be useful in protecting visual function or delay visual loss in secondary intracranial hypertension.

CONCLUSION

We recommend that ONSF should be considered as a meaningful alternative or an adjunct therapy to reduce or delay the visual morbidity of these diseases, although the use of ONSF for some of them remains controversial.

Visual Function Improvement After Optic Nerve Sheath Fenestration in Osteopetrosis Patients with Optic Canal Stenosis: A Report of Two Cases

The outcome of two patients with visual loss from osteopetrosis who underwent an optic nerve sheath fenestration (ONSF) is reported. A 20-year-old male and 26-year-old female with osteopetrosis had optic nerve edema. Computed tomography and magnetic resonance imaging demonstrated optic canals stenosis. Both patients underwent unilateral ONSF. After ONSF, the patients experienced improvement in visual acuity and optic nerve appearance. Therefore, when papilledema is recognized in osteopetrosis patients, it may be reasonable to start with an ONSF even if the optic canal seems to be stenotic because of the lower morbidity that is associated with this procedure compared with other surgical options.

Diagnosis and Management of Osteopetrosis: Consensus Guidelines From the Osteopetrosis Working Group

BACKGROUND

Osteopetrosis encompasses a group of rare metabolic bone diseases characterized by impaired osteoclast activity or development, resulting in high bone mineral density. Existing guidelines focus on treatment of the severe infantile forms with hematopoietic cell transplantation (HCT) but do not address the management of patients with less severe forms for whom HCT is not the standard of care. Therefore, our objective was to develop expert consensus guidelines for the management of these patients.

METHODS

A modified Delphi method was used to build consensus among participants of the Osteopetrosis Working Group, with responses to an anonymous online survey used to identify areas of agreement and conflict and develop a follow-up survey. The strength of recommendations and quality of evidence was graded using the Grading of Recommendations Assessment, Development and Evaluation system.

RESULTS

Consensus was found in the areas of diagnosis, monitoring, and treatment. We recommend relying on characteristic radiographic findings to make the diagnosis and found that genetic testing adds important information by identifying mutations associated with unique disease complications. We recommend ongoing monitoring for changes in mineral metabolism and other complications, including cranial nerve impingement, anemia, leukopenia, and dental disease. We suggest that calcitriol should not be used in high doses and instead recommend symptom-based supportive therapy for disease complications because noninfantile osteopetrosis has no effective treatment.

CONCLUSIONS

Scarcity of published studies on osteopetrosis reduce the ability to develop evidence-based guidelines for the management of these patients. Expert opinion-based guidelines for this rare condition are nevertheless important to enable improved care.

Proliferation and arrest: the genetics of orbital disorders

PURPOSE OF REVIEW

Oculoplastic genetic diseases can be divided into eyelid, lacrimal, and orbital disorders. The purpose of this review is to develop a rational approach to the categorization of genetic diseases that affect the orbit and review the most recent developments.

RECENT FINDINGS

Genetic disorders that affect the orbit can simply be divided into whether they cause proliferation or arrest of orbital structures. Proliferative conditions include vascular, neural, bony, mesenchymal, and lymphoid. Conditions that cause arrest can be subcategorized into whether they cause soft tissue or bony arrest of development. The genetics of many of these conditions have been elucidated and novel treatments, based on the molecular defects, have been utilized with some success.

SUMMARY

Molecular advances may result in substitution of a molecular categorization scheme for the one proposed in this manuscript. Delineation of the underlying molecular causes of these disorders will result in earlier, less invasive procedures than those that are currently employed.

A unifying theory for the multifactorial origin of cerebellar tonsillar herniation and hydrocephalus in osteopetrosis

OBJECT

Osteopetrosis is a rare congenital metabolic bone disease. There are very few reports in the literature associating cerebellar tonsillar herniation (CTH) and hydrocephalus requiring neurosurgical attention. The authors present cases of osteopetrosis requiring neurosurgical intervention from their practice and offer a detailed account of the literature.

METHODS

A retrospective review was conducted at the authors' institution, and all children with osteopetrosis requiring neurosurgical attention were identified. Medical charts and radiographic studies were reviewed. Data including age at presentation, sex, symptoms at presentation, age at follow-up, the presence of any neurological comorbidities, and surgical procedures performed were recorded.

RESULTS

Four patients were identified as having osteopetrosis requiring neurosurgical attention at the authors' institution between January 1, 2005, and January 1, 2014. There were 3 females and 1 male with an average age at presentation of 11.1 years; patients were observed for a mean of 4.4 years. All of the patients were identified as harboring jugular foraminal stenosis and CTH. Seventy-five percent of these patients developed hydrocephalus, and in those cases a triventricular pattern of dilation was noted. One patient developed syringomyelia. Three of the 4 patients underwent neurosurgical procedures. Cerebrospinal fluid diversion was performed in 2 patients via a ventriculoperitoneal shunt in one case and an endoscopic third ventriculostomy (ETV) in the other. The former patient required a proximal revision at 2 years for bony overgrowth at the site of the bur hole. Two patients underwent a suboccipital decompression. In patients undergoing CSF diversion, there was improvement in ventricle size.

CONCLUSIONS

Variable degrees of hindbrain crowding and/or CTH are mentioned throughout the literature, suggesting that this entity is nearly always present in this patient population. The progressive triventricular hydrocephalus seen in these cases results from a complex combination of both communicating and noncommunicating pathology, which may depend on the type of osteopetrosis, age at presentation, and the presence and degree of venous collateralization, and it appears that the hydrocephalus is more prevalent and more likely to be treated in infants and in the younger, school-aged population. The acquired hindbrain fullness in conjunction with the triventricular pattern of hydrocephalus has kept the authors enthusiastic regarding the use of ETV in these complicated cases.

Osteopetrosis

Osteopetrosis is a rare disease that occurs when a child has an unequal balance between new bone growth and elimination of old bone. Children with this entity are able to make new bone tissue, but are not able to break down and eliminate old bones, which is essential for normal bone growth. These thickened and enlarged bones are very weak. These children can exhibit: failure to thrive, macrocephaly, anemia, deafness, and blindness. We will present a case of osteopetrosis, esotropia, and amblyopia of a 7-year-old boy and will discuss the pathophysiology and treatment.

Osteopetrosis with Chiari I malformation: presentation and surgical management

Osteopetrosis is a heterogeneous group of rare, inherited disorders of the skeleton that results in neurological manifestations due to restriction of growth of cranial foramina and calvarial thickening. A 25-year-old woman with a history of autosomal dominant osteopetrosis presented to the authors' institution with headache worsened by exertion and radiating from the occipital region forward with episodes of choking/coughing when eating and a loss of gag reflex on physical examination. On MR imaging, she was found to have severe posterior fossa calvarial thickening resulting in a small posterior fossa and tonsillar ectopia of 9 mm and compression and deformation of the brainstem. She underwent posterior fossa craniectomy, foramen magnum decompression, and partial C-1 laminectomy with external durotomy. The patient did well postoperatively with resolution of symptoms. This case describes a new neurological manifestation of autosomal dominant osteopetrosis. To the authors' knowledge, this report represents the first described case of extreme posterior fossa calvarial thickening from autosomal dominant osteopetrosis with associated Chiari I malformation (CM-I) requiring posterior fossa decompression and extradural decompression. Given previously published MR imaging data that demonstrate the association of osteopetrosis and CM may be more common than in this case alone, the authors discuss the need for further investigation of the incidence of CM-I in patients with autosomal dominant osteopetrosis. Additionally, they review osteopetrosis and other diagnoses of calvarial hyperostosis presenting as CM-I.

[Albers-Schönberg's disease with ocular manifestation]

Albers-Schönberg's disease is a rare disease (one case in 100,000 inhabitants), asymptomatic in the majority of cases. It belongs to the four clearly individualized forms of human osteopetrosis and has an autosomal dominant transmission. It induces generalized osteosclerosis, and most symptoms result from complications such as fractures following mild injury, compression of cranial nerves, especially the optic nerve, by stenosis of extracranial ostia, but also osteomyelitis of the lower maxilla. The treatment of Albers-Schönberg's disease is disappointing and only symptomatic, although the responsible genetic anomaly was recently identified. We report here the case of a 54-year-old woman, whose diagnosis of the disease has been known since adolescence, who presented with unilateral loss of vision and perimetric deficit due to papilla edema resulting from stenosis of the optic canal and benign intracranial hypertension.

Optic nerve trauma with unilateral edema as a result of head injury

We encountered a patient who suffered a head injury that translated to the optic nerves, leading to dramatic unilateral right optic nerve edema. The decedent was a 20-year-old unsecured passenger in a convertible. The car collided with a pickup truck. The patient survived for 8 h. At autopsy, a comminuted skull fracture involving the right frontal bone including the right orbital plate was found. The right optic nerve measured 1.2 cm in diameter, compared to only 0.4 cm for the left optic nerve. Microscopically, the right optic nerve was markedly edematous, but the nerve fibers and nuclei were viable and intact. The dramatic difference in size between the right and left optic nerves can be attributed to several mechanisms. The survival interval was essential for the asymmetrical swelling to take place. Optic nerve trauma is relatively rare in head injuries, reported to be present in 0.5% of automobile accidents and assaults. Other causes of optic nerve trauma and edema include tumors, osteopetrosis, or reaction to a peripheral hemodialysis shunt.

Bilateral jugular foraminal stenosis in a patient with benign osteopetrosis associated with pseudotumor cerebri syndrome

One of the prominent causes of pseudotumor cerebri (PTC) syndrome is increased impedance of the venous outflow tracts of the brain. Theoretically, this is a justified mechanism for raised intracranial pressure; yet, there had been few cases of such a scenario reported in the literature, and to the authors' knowledge no case of PTC due to benign osteopetrosis has been reported to date. The present case occurred in a 19-year-old woman with a constellation of signs and symptoms compatible with PTC syndrome, whose radiological and laboratory studies confirmed the diagnosis of osteopetrosis. Magnetic resonance venography demonstrated bilateral jugular foraminal stenosis regarding the underlying disease process. The patient did well after she underwent a lumboperitoneal shunt insertion procedure.