Functional impairments caused by chiasma syndromes prior to and following transsphenoidal pituitary adenoma surgery

PURPOSE

To describe the functional impairment caused by chiasma syndromes (CS) prior to and following transsphenoidal pituitary adenoma surgery.

METHODS

Pertinent data of a successive series of patients operated transsphenoidally for the first time for pituitary adenoma were retrospectively analyzed. The degree of functional impairment caused by the impairment of vision was quantified according to the resulting degree of disability (DOD). A DOD of > or =30 is considered substantial.

RESULTS

None of the 197 of 304 (64.9%) patients without preoperative chiasma syndrome (CS) experienced postoperative worsening of their visual acuity or their visual fields. Thus, no change of their vision-related DOD (V-DOD) did occur. One hundred and seven (35.1%) of the patients presented preoperatively with CS. Postoperatively, 42.9% of the CS remitted completely, 38.3% improved, 11.2% remained unchanged, and 7.4% worsened. Accordingly, the median V-DOD improved significantly from 30 (0; 100) to 0 (0; 100). The prevalence of patients with V-DOD > or =30 dropped significantly from 51.4% preoperatively to 16.4% postoperatively. Postoperatively, the median V-DOD improved significantly up to 3 months postoperatively. Thereafter, no further significant changes occurred. However, in patients with preoperative CS, the median V-DOD as well as the prevalence of patients with a V-DOD > or =30 remained postoperatively significantly higher compared to patients without preoperative CS.

CONCLUSIONS

Visual impairments due to CS frequently caused substantial DOD preoperatively. Postoperatively, the median degree of V-DOD as well as the prevalence of substantial V-DOD improved significantly. However, in patients with preoperative CS, V-DOD remained postoperatively significantly higher than V-DOD of patients without preoperative CS.

[Case of traumatic chiasmal syndrome]

BACKGROUND

Traumatic neuropathy of the optic chiasm is a rare finding which occurs after severe blunt head trauma. It is often accompanied by dysfunction of the pituitary gland and hypothalamus and called traumatic chiasmal syndrome. We report a patient with traumatic chiasmal syndrome caused by a severe traffic accident.

CASE

A 25 year-old woman was referred for bitemporal visual field defects caused by a traffic accident two months before. Corrected visual acuity was 0.05 in the right eye and 1.2 in the left eye. Bilateral optic atrophy and relative afferent pupillary defect in the right eye were found. Magnetic resonance imaging revealed an enlarged optic chiasm. Computed tomography disclosed many fractures in the skull including the back wall of the sphenoid sinuses. She also suffered from diabetes insipidus and anosmia.

CONCLUSION

Traumatic optic neuropathy of the optic chiasm is a rare condition which can be differentiated from neuropathy in the optic canal by considering the patterns of visual field defects and their accompanying signs.

Subarachnoid Hemorrhage and Vasospastic Stroke After Self-Enucleation

A 31-year-old intoxicated woman self-enucleated her left eye during an acute psychotic episode. CT revealed avulsion of the intracranial optic nerve, chiasmal edema, and adjacent subarachnoid hemorrhage. Exploration via transconjunctival orbitotomy was performed, and the globe and 4.8 cm of contiguous optic nerve were removed. The patient developed postoperative contralateral visual loss followed by middle cerebral artery vasospasm and bilateral cortical infarcts.

Brain & chiasmal herniations into sella after medical treatment of prolactinoma

BACKGROUND

Dopamine agonists are widely used in the treatment of pituitary prolactinomas. We report a case of inferior mesial frontal lobe (gyrus rectus) and chiasmal herniations into an enlarged sella following successful medical treatment of a pituitary macroadenoma.

METHOD

A 71-year-old healthy man presented to medical attention with visual complaints. On examination, he was found to have bitemporal hemianopsia. Endocrine evaluation revealed an elevated prolactin level. He was treated medically with a dopamine agonist (bromocriptine).

RESULTS

Evaluation after one year of medical treatment revealed stabilization of the patient's vision, with a significant bitemporal field loss. Serum prolactin levels normalized (5.16 ng/ml). The MRI of the sella showed almost complete disappearance of the tumor, resulting in right mesial frontal lobe herniation inferiorly into an enlarged sella with associated chiasmal deformation.

CONCLUSIONS

We report a case where successful medical treatment of a large pituitary prolactinoma has resulted in inferior frontal lobe and chiasmal herniatons into an enlarged sella.

Endonasal endoscopic transsphenoidal chiasmapexy with silicone plates for empty sella syndrome: technical note

Silicone plates sutured together to form blocks were used for extradural elevation of the sella floor in two patients who underwent chiasmapexy for visual disturbance associated with empty sella syndrome. A 36-year-old woman had been treated for prolactinoma for about 19 years with bromocriptine and then presented with left visual disturbance. A 79-year-old man presented with right blurred vision of unknown cause other than empty sella. The sella turcica was accessed via the endonasal transsphenoidal approach under endoscopic guidance. The bony sellar floor was opened with a drill. Two or three pieces of 1-mm-thick silicone plate were sutured to make a block. Two or three blocks were inserted into the epidural space to elevate the sellar contents. Visual symptoms improved in both patients. Silicone is biocompatible and not absorbable. Silicone plates are elastic and easy to handle during insertion, but firm enough to support the sella. The elevation can be adjusted by changing the number of plates in the block. The endonasal endoscopic approach is minimally invasive and particularly suitable for transsphenoidal extradural chiasmapexy for empty sella syndrome.

Visual outcome of blind eyes in pituitary apoplexy after transsphenoidal surgery: a series of 14 eyes

BACKGROUND

To study the visual outcome of patients who became blind after an episode of pituitary apoplexy and who subsequently underwent emergency transsphenoidal decompression of the optic apparatus, and to identify factors that may have a bearing on the visual outcome in such patients.

METHODS

Twenty-three patients underwent transsphenoidal surgery for pituitary apoplexy over a 5-year period at the All India Institute of Medical Sciences. Among them, 8 (35%) presented with visual deterioration to monocular (n = 2) or binocular (n = 6) blindness after the apoplectic episode. There were 7 males and 1 female with the average age of patients being 43 years. The mean delay between the apoplexy and neurosurgical consultation was 10 days, with a range of 4 to 30 days. The adenoma was classified as "giant" in 4 and multicompartmental in 2 patients. After surgery, all patients had a minimum follow-up of 3 months.

RESULTS

Four patients (50%) had improvement in vision to greater than 2/60 (Snellen's), including 2 patients whose vision improved to 6/6. All patients in whom there was improvement in vision had been operated on within a week of the apoplectic episode.

CONCLUSIONS

This study shows that even completely blind eyes may have remarkable improvement in vision if surgical decompression of the optic apparatus is undertaken early. Awareness regarding pituitary apoplexy and reversibility of vision loss needs to be increased among the medical community, especially ophthalmologists and physicians, so that timely neurosurgical intervention can occur.

Giant Intrasellar Arachnoid Cyst Manifesting as Adrenal Insufficiency Due to Hypothalamic Dysfunction-Case Report-

A 67-year-old man first noticed loss of pubic and axillary hair in 1992 and then a visual field defect in 2001. He experienced loss of consciousness attributed to hyponatremia in April 2002. Magnetic resonance imaging showed a giant intrasellar cystic mass, 40 mm in diameter, that had compressed the optic chiasm. The patient complained of chronic headache, and neurological examination revealed bitemporal hemianopsia. Preoperative endocrinological examination indicated adrenal insufficiency, and hypothyroidism due to hypothalamic dysfunction. The patient underwent endonasal transsphenoidal surgery. The cyst membrane was opened and serous fluid was drained. Histological examination identified the excised cyst membrane as arachnoid membrane. The patient's headaches resolved postoperatively, but the bitemporal hemianopsia and endocrinological function were unchanged. This arachnoid cyst associated with hypothalamic dysfunction might have been caused by an inflammatory episode in the suprasellar region.

Delayed visual deterioration after pituitary surgery--a review introducing the concept of vascular compression of the optic pathways

BACKGROUND

Delayed visual deterioration after pituitary surgery has been attributed to secondary empty sella syndrome and downward herniation of the optic nerves and chiasm, but the pathophysiological basis of this condition is still a matter of debate.

REVIEW

According to the literature, prior radiation therapy, previous visual impairment and transcranial surgery constitute risk factors for delayed visual deterioration. Radiation-induced vascular changes and/or strangulation of the optic nerves or chiasm are thought to compromise local blood flow. Downward herniation of the optic pathways was present in the majority of cases, but did not correlate with visual symptoms and signs, while dense scarring of the chiasm was a reproducable finding in all surgically explored cases. Indentations in the upper margin of the optic nerves or chiasm caused by the A1 segments of the anterior cerebral arteries have been reported repeatedly. As perichiasmal scarring constitutes the most consistent finding, the intimate relationship between artery and nerve with consecutive pulsatile pressure may constitute a causative factor in delayed visual dysfunction after pituitary surgery. The authors therefore introduce the concept of vascular compression, which is illustrated with a personal case of a successful decompression procedure with teflon interposition between the A1 segment and the non-herniated optic nerve to treat visual loss eight months following removal of a hemorrhagic pituitary adenoma.

CONCLUSIONS

Clinicians should be aware that surgical exploration via a transcranial approach is indicated in cases of progressive visual loss late after pituitary surgery, no matter whether downward displacement of the optic pathways is present on imaging studies or not. Special attention should be paid intra-operatively to the dissection of the intimate relationship between the anterior cerebral arteries and the optic nerves and chiasm.

Preliminary visual field preservation after staged CyberKnife radiosurgery for perioptic lesions

OBJECTIVE

The limited radiation tolerance of the optic nerves and the optic chiasm makes it a challenge to treat immediately adjacent lesions with radiosurgery. Staged or hypofractionated radiosurgery has the virtue of combining the accuracy and conformality of radiosurgery with the normal tissue-sparing benefits of fractionation. We describe a consecutive series of patients with meningiomas and pituitary adenomas abutting the anterior visual pathways who were treated with staged, image-guided radiosurgery.

METHODS

Thirty-four patients with either meningiomas (20 patients) or pituitary adenomas (14 patients) within 2 mm of the optic apparatus were treated. Several patients had previously been treated with conventional fractionated radiotherapy (5 patients) or subtotal surgical resection (23 patients). Radiosurgery was delivered in two to five stages to a cumulative average marginal dose of 20.0 Gy. Visual testing and clinical examinations were performed before treatment and at follow-up intervals beginning at 6 months after treatment.

RESULTS

The mean follow-up period was 29 months (range, 15-62 mo). Pre- and posttreatment vision was unchanged in 20 patients, improved in 10, and worse in 3. One patient died during follow-up as a result of an unrelated cardiac event. Visual loss was accompanied by tumor progression in two cases. In a third patient with a multiply recurrent adrenocorticotropic hormone-secreting pituitary adenoma, injury to one optic nerve occurred after both a prior course of radiotherapy and three separate sessions of radiosurgery.

CONCLUSION

Staged radiosurgery resulted in high rates of tumor control and preservation of visual function. Ninety-one percent of patients retained their presurgical vision. Staged radiosurgery may be a safe and effective alternative to either surgery or fractionated radiotherapy for selected lesions adjacent to the optic apparatus.

Traumatic dysfunction of the optic chiasm

BACKGROUND

Trauma of the optic chiasm has been reported but its incidence is low.

PATIENTS AND METHODS

Retrospective review of patients diagnosed with traumatic optic neuropathy between 1992 and 2002.

RESULTS

Among 91 patients with a diagnosis of traumatic optic neuropathy, 10 showed evidence of optic chiasm involvement. All were males, the average age was 32 years (range 22-43). Injuries resulted from a rapid deceleration in 8 cases (car or motorcycle accident or fall from a minimum height of 5 meters). Coma was present in 6 cases and neurologic disorders in 8 cases. Optic neuropathy was present in 8/10 cases. Visual improvement was noted in two patients who suffered from milder head trauma.

CONCLUSIONS

Optic chiasm dysfunction following head trauma is not that rare, as 11 % of our traumatic optic neuropathy group presented such a dysfunction. In some cases the visual field defect was obvious, but in some others it was more subtle. Visual prognosis was generally poor, probably related to the the severity of the impact.

Traumatic chiasmal syndrome: a series of 19 patients

PURPOSE

To present a clinical series of 19 patients with traumatic chiasmal syndrome.

METHODS

A retrospective study was performed. This included all patients with traumatic chiasmal syndrome seen in the neuro-ophthalmology clinic at the Royal Adelaide Hospital between January 1970 and January 2000.

RESULTS

Of the 19 study patients, most were young males involved in motor accidents. Two-thirds had skull fractures. Three-quarters of patients had a final visual acuity of 6/12 or better in at least one eye. Ten patients had a complete optic nerve palsy. The incidence of diabetes insipidus in this study was 37%. The incidence of cranial nerve lesions, hypopituitarism, carotid cavernous fistula, and other deficits were documented. Magnetic resonance imaging and surgical findings were consistent with known mechanisms of chiasmal injury.

CONCLUSIONS

Trauma is a rare cause of chiasmal syndrome. Patients with bitemporal field defects should be questioned about prior head injury. In the acute setting, magnetic resonance imaging is the most useful investigation. The treating practitioner should anticipate and treat associated endocrine, ocular motility, and other disorders. Mechanisms of damage to the optic chiasm after trauma include direct tearing, contusion haemorrhage and contusion necrosis. These mechanisms should not be considered mutually exclusive. Unilateral temporal hemianopia with a fellow blind eye is not necessarily the result of chiasmal disruption.

[A case of traumatic chiasmal syndrome presenting with bitemporal upper quadrantanopsia]

A 22-year-old woman was involved in a motor vehicle accident and suffered a craniofacial injury. The patient was treated conservatively with a diagnosis of cerebral contusion in the frontal base confirmed with MR images. When the patient regained consciousness one week after the accident, she had a complete form of bitemporal upper quadrantanopia. A bone window level CT scan showed a linear fracture in the middle of the frontal base running longitudinally and extending posteriorly down to the sella turcica and clivus. Axial MR images parallel to the optic pathway revealed a T2 bright lesion in the anterior half of the optic chiasm. The patient recovered gradually and returned to her previous life-style six months later without complaining of diplopia, but her visual field defect was left unchanged. Traumatic chiasmal syndrome is rare and usually presents bitemporal hemianopsia. Very rarely, bitemporal quadrantanopsia has been reported. Given the anatomical structure that the neural fibers from the lower nasal part of the retina run posteriorly in the optic nerve and cross the anterior half of the optic chiasm to enter the contralateral optic tract, the lesion in the optic chiasm seen in the MR images seemed to be the causative lesion of bitemporal upper quadrantanopsia in our patient. The optic chiasm appeared to be injured by a laterally stretching force exerted in an antero-posterior direction when the medial basal fracture occurred.

Translaminar differentiation of visually guided behaviors revealed by restricted cerebral cooling deactivation

The purpose of the present study was to test the hypothesis that superficial and deep layers within a single cerebral region influence cerebral functions and behaviors in different ways. For this test, we selected posterior middle suprasylvian (pMS) sulcal cortex of the cat, a suspected homolog of the area V5 complex of primates, because the region has been implicated in several visually guided behaviors. Cats were trained on three tasks: (1) discrimination of direction of motion; (2) discrimination of static patterns partially obscured by static or moving masks; and (3) visual detection and orienting. Cooling of cryoloops in contact with pMS sulcal cortex to 8+/-1 degrees C selectively and completely impaired performance on the two motion discrimination tasks (1 and 2), while leaving the detection and orienting task (task 3) unimpaired. Further cooling to 3 degrees C resulted in an additional complete impairment of task 3. The 8 degrees C temperature resulted in silencing of neuronal activity in the supragranular layers (I-III) and the 3 degrees C temperature silenced activity throughout the thickness of pMS sulcal cortex. The variation in behavioral performance with covariation of cryoloop temperature and vertical, but not lateral, spread of deactivation shows that deactivation of superficial cerebral layers alone was sufficient to completely impair performance on the two motion discrimination tasks, whereas additional deactivation of the deep layers was essential to block performance on the detection and orienting task. Thus, these results show a functional bipartite division of labor between upper and lower cortical layers that is supported by efferent connectional anatomy. Similar bipartite division into upper and lower layers may be a general feature of cerebral cortical architecture, signal processing and guidance of behavior.

Traumatic transection of the optic chiasm: magnetic resonance evaluation

Disruption of the optic chiasm is a rare complication of head trauma. We present the findings on MRI of this entity in a 40-year-old patient presenting with bitemporal hemianopia.

Intracranial penetrating injuries via the optic canal

Two cases of intracranial penetration of a plastic or wooden chopstick via the optic canal are described. CT scans showed the chopsticks as linear hypodense structures in the suprasellar cistern contiguous with the optic canal. In one case, MR imaging was performed, which clearly depicted the foreign body and adjacent brain structures. Although they are extremely rare, transorbital intracranial penetrating injuries via the optic canal require physicians' awareness.

[Temporal hemianopia and diabetes insipidus following head injury]

Bitemporal hemianopia and diabetes insipidus following head injury are caused by a lesion in the center of the optic chiasm, together with injury to the adjacent pituitary stalk or the hypothalamus. This combination was thought to be a rare complication of severe head injury. The case of a 16-year-old male is presented, which together with recent reports suggests that this relatively under-recognized syndrome is not infrequent, that it may follow even minor head injury, and that magnetic resonance imaging can demonstrate the chiasmal lesion.

A sellar misadventure--imaging considerations

This report describes a patient with a headache and a bitemporal hemianopsia immediately following endoscopic ethmoid and sphenoid sinus surgery. Computed tomographic imaging revealed tension pneumocephalus caused by surgical interruption of the boundaries between the sinus(es) and the anterior cranial cavity. The delineation of the central chiasmal injury required follow-up magnetic resonance imaging.

Anterior chiasmal optic nerve avulsion

In a case of traumatic avulsion of the optic nerve at the anterior chiasm, MR imaging provided highly specific images of the injury site, including the absence of the optic nerve within the optic canal and the point of transection at the anterior portion of the chiasm. This was confirmed clinically and histopathologically. MR imaging should be considered in cases of suspected chiasmal injury.

Traumatic chiasmal syndrome: a feature photograph

Traumatic chiasmal neuropathy results from injury to the face, sphenoid and clivus. Its pathogenesis remains enigmatic. Because of its close relationship to the pituitary gland, hypothalamus and internal carotid artery, a neuro-ophthalmic evaluation and imaging is needed in such cases. We present a patient who developed traumatic chiasmal syndrome after an automobile accident. Computed tomographic scan showed fracture of the sella turcica. A carotid angiography showed a traumatic pseudoaneurysm of the internal carotid at the base of the skull.

Traumatic neuropathies of the optic nerve, optic chiasm, and ocular motor nerves

This review focuses on traumatic chiasmal syndrome and traumatic neuropathies of cranial nerves II, III, IV, and VI. The review highlights common anatomical sites of injury to the above structures. Special emphasis is placed on review of recent literature. Other review of related material include.

[Ophthalmological symptoms of visual tract lesions in craniocerebral injuries]

Craniocerebral injuries are known to involve the visual tract in 2-5% of cases. Fifty-nine patients aged 5 to 68 with visual tract involvement in craniocerebral injury were examined in N. N. Burdenko Institute of Neurosurgery of the Russian Academy of Medical Sciences. Unilateral optic nerve involvement was found in 48 patients, involvement of the chiasm and/or both optic nerves in 11. Involvement of a single optic nerve was associated with vision acuity reduction, 30 patients becoming blind or virtually blind, and with various defects of the visual field. Traumatic injury to the chiasm manifested as a rule by the asymmetric chiasmal syndrome. Follow-up of the patients in the acute period of craniocerebral injury showed that paling of the optic disc manifested in various periods after the moment of the injury, from 3-4 days to 1 month, this depending on the localization of the injury and its distance from the posterior pole of the eye. Besides visual disturbances and ophthalmoscopic changes, oculomotor disorders were found which were caused by traumatic impairment of the oculomotor nerves (in the orbit or skull) and muscles. Transcutaneous electrostimulation of the injured optic nerves was sufficiently effective, its efficacy directly depending on the period elapsed since the injury, excepting blind or virtually blind patients.

Electrodiagnostics of chiasmal compressive lesions

Recording of visual evoked potentials (VEPs) is not yet a routine test in patients with suspected chiasmal compressive lesions, but has proved useful to a clinician in assessing and following-up visual pathway dysfunctions. Abnormalities of VEPs can be found even in patients without clinical evidence of the visual impairment: VEP delays and alterations of the waveform, asymmetric distribution in one eye or in both eyes (crossed asymmetry) can indicate chiasmal compressive lesion. Simultaneous recording of pattern electroretinograms (PERGs) can additionally provide useful information about the patient's cooperation as well as about eventual retrograde degeneration of the ganglion cells. Electrophysiologic tests can be regarded as an integral part of diagnostic procedures--ocular diagnostic tests and neuroimaging--in suspected compressive lesions of the optic chiasm.

Traumatic chiasmal syndrome associated with midline basilar skull fractures

We studied two young males who had visual field defects consistent with optic chiasmal injury after blunt frontal head trauma. One patient also had a unilateral optic neuropathy. Long-term follow-up disclosed complete bi-temporal hemianopsias in these patients. Both patients had midline basilar skull fractures that traversed the midclivus through the sella turcica floor, dorsum sellae, and sphenoid sinus. Magnetic resonance images did not identify intrachiasmal hemorrhage as the cause of the visual field defect. We believe this fracture pattern, in conjunction with the magnetic resonance image findings, suggests tearing of the optic chiasm on a microscopic, if not macroscopic, scale as the cause of the complete bitemporal hemianopsia.

Chiasmal trauma: clinical and imaging considerations

This report presents a patient who sustained closed head injury with chiasmal trauma. This uncommon injury may not be apparent on routine imaging studies. It is significant, not only from the visual standpoint, but also because of the association with serious conditions, such as panhypopituitarism, traumatic carotid aneurysm, carotid cavernous fistulae, and meningitis associated with leakage of cerebrospinal fluid. This report demonstrates that magnetic resonance imaging (MRI) is the best method for identifying chiasmal abnormalities.

[Traumatic avulsion of the optic nerve in the chiasm region]

Avulsion of the optic nerve in the chiasmal region is a very rare injury. The authors presented a case of such avulsion with concomitant temporal visual field defect in the other eye. The pathomechanism of this type of optic nerve injuries is discussed.

Post-traumatic chiasmatic disruption

Ten patients with traumatic disruption of the optic chiasm are presented. The clinical sequence of fronto-facial trauma and CSF rhinorrhoea, followed days later by diabetes insipidus and discovery of a bi-temporal visual field loss constitute a characteristic syndrome which should be recognized by the attending medical staff. Magnetic resonance imaging, not previously reported, and post-mortem evidence point to a physical disruption of the chiasm and infundibulum as the cause of the visual and hypothalamic signs. The resulting field defect is permanent but the diabetes insipidus is transient in 50% of patients and can be adequately managed with manipulation of the patient's fluid intake.

Traumatic lesions of the suprasellar region: MR imaging

The authors studied nine patients with injuries to the suprasellar region with 1.5-T magnetic resonance (MR) imaging. Five patients had chiasmal injuries diagnosed by means of clinical examination. MR imaging demonstrated complete transection in two of these five patients, contusion of the chiasm by inferior herniation of the gyrus rectus in one, and a normal chiasm in two. Two patients had large tears of the floor of the third ventricle resulting in wide communication between the third ventricle and the prepontine cistern. One of these patients also had an avulsed third nerve. Transection of the pituitary stalk was seen in two patients. MR imaging can demonstrate injuries to the suprasellar structures. The MR imaging appearance of optic chiasm correlates with different types of injury to the chiasm described in the clinical literature and may alleviate the need for additional diagnostic studies to help explain the patient's symptoms.

Visual abnormalities with multiple trauma

The diversity of pathogenetic mechanisms involved in posttraumatic visual impairment was reviewed in a study of the hospital records of 24 patients admitted with multiple injuries. Most major visual abnormalities occurred in young people (average age 33 years) who presented with a wide range of overall severity of injury (injury severity score 13-47) and involvement of the central nervous system (Glasgow coma scale 5-15). Bilateral or monocular blindness developed in 63% of patients. Seventy percent of the injuries involved the anterior visual pathways with damage to the optic nerve alone accounting for 35%. Fractures of the sphenoid bone, particularly of the body, accompanied optic nerve and chiasmal injuries and some cases of traumatic carotid-cavernous fistulas. Pathogenetic mechanisms varied according to the site of injury and included vitreous hemorrhage and optic atrophy secondary to raised intracranial pressure, retinal hypoxia from carotid-cavernous fistulas, shearing and compression injuries of the optic nerve, traumatic chiasmal syndrome, temporoparietal and occipital contusions, and transtentorial herniation with occipital infarction. Visual abnormalities varied in severity from moderately reduced visual acuity and diverse hemianopias and scotomas to blindness. The incidence of posttraumatic residual visual abnormalities is likely to increase in the wake of improved acute care of the traumatized victim.

Receptive field sizes and responsiveness to light in area 18 of the adult cat after chiasmotomy. Postoperative evolution; role of visual experience

Receptive field sizes to stimulation of the ipsilateral temporal retina were studied in area 18 of adult cats at different times after complete midsagittal section of the optic chiasm. A specific postoperative evolution could thus be noticed: immediately after section, the average area of the receptive fields was reduced, as compared to control preparations, owing to the disappearance of large fields located at more than 20 degrees of eccentricity. A progressive reappearance of these large fields occurred between 8 and 45 days after chiasmotomy, provided that the animal was placed in normal visual conditions during its postoperative period. No such recovery could be assessed after as long as 55 days, in animals kept in complete darkness after operation. Chiasmotomized cats also displayed a reduction of their percentage of light reactive cells with respect to controls, as expected from the suppression of the contralateral input. This percentage was at first very low and progressively increased, during postoperative recovery but again not when the animal had been kept in the dark. Finally, an increase of cells with "diffuse responses" was observed in the late postoperative recovery stage. This latter evolution also appeared to depend upon postoperative visual experience. On the other hand, no clear indication of an interhemispheric transfer could be obtained in these experiments, even at the 17-18 boundary.

Traumatic chiasmal syndrome

We studied 11 patients with the uncommon finding of traumatic chiasmal syndrome after closed head trauma. Visual field defects varied from complete monocular blindness and contralateral temporal hemianopia to subtle bitemporal arcuate scotomas. The degree of visual loss was not necessarily related to the severity of the craniocerebral trauma. Diabetes insipidus was present in half of these patients, but unlike the visual abnormalities, this complication was transient.

Visual abnormalities after severe head injuries

The authors studied 12 patients with major abnormalities of the afferent visual system following closed injury to the head. The anatomic sites of injury were the eye in five patients, the optic nerve in seven patients, the chiasm in four patients and the optic radiations in four patients. A technique for rapid evaluation of the afferent visual system in patients with multiple injuries is presented. Three representative examples of permanent visual loss following closed head injury are reported.

[Avulsio bulbi (author's transl)]

It is reported about a 14 year old girl, sustaining an avulsion of the left eye-ball by a coat-rack. The optic nerve was cutted 18 mm retrobulbarly. In perimetry of the fellow-eye a temporo-superior defect was found as proof of traumatisation of the anterior-loop-fibers in the chiasm.

Traumatic bitemporal hemianopsia: case report

Bitemporal hemianopsia due to trauma to the optic chiasm is uncommon following head injury. In the patient described, a hemianopic field defect was seen 12 days after frontal basilar skull fracture. We feel the cause is intrachiasmatic contusion, edema, and hemorrhage. Serial ophthalmologic examinations and possibly use of steroids are recommended.

Traumatic hypopituitarism associated with bitemporal hemianopia in a prepuberal child

The case of a boy affected by post-traumatic hypopituitarism associated with bitemporal hemianopia is described. While traumatic bitemporal hemianopia is not an extraordinary occurence, traumatic injuries have been rarely reported among the causes of hypopituitarism. This may be because the cranial trauma in most of the cases is too severe to permit survival. After having considered the diagnostic problems the authors briefly review the peculiar vascular supply to the chiasma and anterior diencephalon and try to consider the pathogenetic mechanism of the syndrome. Direct contusion necrosis and direct intraparenchymal hemorrage in the chiasma and in the hypophysis or hypothalamus are considered the most probable causal factors; however, the concomitant occurence of chiasmal and hypopituitary injury might be explained by a single transient compressive mechanism either on the tubero-hypophysial arteries or on the smaller vessels of the infundibular network. The difficulty of ascertaining both the pathogenetic mechanism and the seat of the endocrine lesions on the basis of the clinical signs is stressed.

[Traumatic lesions of the optic chiasma (author's transl)]

Traumatic lesions of the chiasma are few when one considers its anatomical position. They happen after severe direct or indirect traumas with or without skull fractures, and with or without macroscopic lesions. Microscopic lesions are characterised by contusion. Clinically the visual loss goes together with bitemporal defects and with bilateral hemorrhagic papillar oedema. Early complications are hematoma of the optochiasmatic space and perichiasmatic meningitis: among delayed complications optochiasmatic arachnoiditis prevails.