Locus coeruleus syndrome as a complication of tectal surgery.

We describe a case of a 48-year-old woman who underwent a resection of a tectal pilocytic astrocytoma complicated by a sequence of fluctuating consciousness, psychosis with complex hallucinations and lasting sleeping disturbances in which she vividly acts out her dreams. Based on the clinical and anatomical evidence of this case, we propose the term locus coeruleus syndrome to describe this association of iatrogenic symptoms. Along with those of the locus coeruleus, lesions of the dorsal raphe nucleus, ventral tegmentum, substantia nigra pars compacta, the superior colliculus and other peduncular lesions (such as peduncular hallucinosis) are involved in the regulation of sleep-wake/arousal, behaviour, sleeping disorders and rapid eye movement atonia. However, iatrogenic lesion of the locus coeruleus could explain the complications on all levels in our patient.

Lateral inferior cerebellar peduncle approach to dorsolateral medullary cavernous malformation.

OBJECT: Brainstem cavernous malformations (BSCMs) present a unique therapeutic challenge to neurosurgeons. Resection of BSCMs is typically reserved for lesions that reach pial or ependymal surfaces. The current study investigates the lateral inferior cerebellar peduncle as a corridor to dorsolateral medullary BSCMs. METHODS: In this retrospective review, the authors present the cases of 4 patients (3 women and 1 man) who had a symptomatic dorsolateral cavernous malformation with radiographic and clinical evidence of hemorrhage. RESULTS: All patients underwent excision of the cavernous malformation via a far-lateral suboccipital craniotomy through the foramen of Luschka and with an incision in the inferior cerebellar peduncle. On intraoperative examination, 2 of the 4 patients had hemosiderin staining on the surface of the peduncle. All lesions were completely excised and all patients had a good or excellent outcome (modified Rankin Scale scores of 0 or 1). CONCLUSIONS: This case series illustrates that intrinsic lesions of the dorsolateral medulla can be safely removed laterally through the foramen of Luschka and the inferior cerebellar peduncle.

Interpeduncular arachnoid cysts in infants and children: insight into the entity based on a case series with long-term follow-up.

OBJECTIVE: Arachnoid cysts occupying the suprasellar region comprise 10-15% of intracranial distribution. Unlike large suprasellar cysts, pure interpeduncular cysts (IPCs) are rare, and their natural history is unknown. We describe a small series of children diagnosed with IPC and their long-term natural history. METHODS: A retrospective review was conducted of interpeduncular arachnoid cysts diagnosed over the years 2000-2010 at our center. Patients with clearly suprasellar cysts were excluded. Serial magnetic resonance imaging and long-term follow-up examinations were analyzed. Additionally, we conducted an extensive literature review focusing on the differences between suprasellar cysts and IPCs. RESULTS: We identified three pediatric patients with "pure" IPC; all of these had a follow-up of more than 5 years, and none was operated. Only six additional cases were identified in the literature. In both our experience and in the literature review, IPCs proved stable over the course of time, both radiologically as well as clinically. CONCLUSIONS: The clinical and radiological features of IPCs are not well defined. Variations in the relationship of arachnoid cysts in this area to Liliequist's membrane may explain the different subgroups that have been identified as well as the confusing nomenclature. IPCs are usually diagnosed as incidental findings or present with mild endocrine disorders. Associated findings of hydrocephalus, mass effect, and compression of neighboring structures, such as the chiasm, are not as frequent as with suprasellar cysts. Given the high likelihood of continuing stability, a conservative strategy of follow-up is recommended for pure IPCs that demonstrate preservation of the third ventricle.

Endoscopic treatment of the suprasellar arachnoid cyst.

Surgical options for suprasellar arachnoid cyst are cystoperitoneal shunt, craniotomy fenestration and endoscopic fenestration. Endoscopic management has been found to be safe and effective. We report our experience with endoscopic management in 12 (male five, female seven; age range 8 months to 42 years) patients with suprasellar arachnoid cyst. The endoscopic procedure included lateral ventricle puncture by precoronal burr hole and superior and inferior wall of the cyst was communicated with the lateral ventricle and the interpeduncular cistern respectively. All patients had hydrocephalus. Four pediatric patients had macrocephaly. All adult patients had visual disturbances. One adult patient presented with psychomotor disturbance along with features of raised intracranial pressure. All cases improved following endoscopic treatment. There were no complications or death. One patient required VP shunt. Postoperative MRI showed significant reduction in cyst volume in 11 patients. Follow-up ranged from 6 months to 6 and a half years. Our study suggests that endoscopic technique is a safe and effective alternative treatment for suprasellar arachnoid cyst. It prevents complications such as subdural effusion and intracranial hematoma, which are not uncommon with craniotomy fenestration.

Cavernous hemangioma of the mesencephalon: tonsillouveal transaqueductal approach.

OBJECTIVE: Recent advances in microsurgical techniques facilitate surgical resection of brainstem lesions that were previously considered inoperable. In this article we present, for the first time, the tonsillouveal transaqueductal approach to access a progressively symptomatic cavernoma within the depth of the tegmentum of the mesencephalon. METHODS: A 52-year-old woman presented with a history of slowly progressive right-sided hemiparesis and ataxia. On magnetic resonance imaging, a relatively large cavernoma involving the tegmentum of the mesencephalon was shown. The sylvian aqueduct was patent and there was no secondary ventriculomegaly. The patient underwent surgery via a suboccipital craniotomy and C1 laminectomy. The right tonsillouveal and medullotonsillar spaces were opened to the level of the choroidal point of the posteroinferior cerebellar artery. The tela choroidea was incised from the foramen of Magendie to the telovelar junction. Looking through the aqueduct and at a point 5 mm superior to its inferior inlet, there was a small cherry-like blister protruding into the aqueductal anterior surface. This was used as an entry point to access the cavernoma. The space around the cavernoma was gently dissected and the cavernoma was circumferentially coagulated to shrink it in a concentric manner toward its center. RESULTS: The total removal of the lesion was achieved and the histopathological findings were consistent with a cavernoma. As a result of noncommunicating hydrocephalus, the patient needed a ventriculoperitoneal shunt. The 1-year postoperative neurological examination was consistent with preoperative findings. CONCLUSION: This report shows, for the first time, direct surgical removal of a cavernous hemangioma in the mesencephalic tegmentum via the aqueduct. This approach adds to contemporary microneurosurgery, respecting functional anatomy and minimizing neurological deficits.

Endoscopic endonasal pituitary transposition for a transdorsum sellae approach to the interpeduncular cistern.

OBJECTIVE: The interpeduncular cistern, including the retroinfundibular area, is one of the most challenging regions to approach surgically. The pituitary gland and the infundibulum guard the region when an endonasal route is undertaken. Superior transposition of the pituitary gland and infundibulum is described as a functional means to access this complex region through a fully endoscopic, completely transnasal route. METHODS: Ten consecutive patients in whom a pituitary transposition was performed during an expanded endonasal approach at the University of Pittsburgh Medical Center for resection of retroinfundibular lesions were reviewed. The series consisted of seven men and three women with a mean age of 44.4 years. Pathology consisted of four craniopharyngiomas, four chordomas, and two petroclival meningiomas. RESULTS: Five patients (50%) underwent total resection of the tumor, three patients (30%) underwent near total resection ( > 95% removal), and two patients (20%) had partial resection of petroclival meningiomas with the goal of optic apparatus decompression. All four patients with visual deficits recovered their vision completely. There was no neurological deterioration. Eight patients had normal pituitary function preoperatively, seven of whom (87.5%) had confirmed function preservation postoperatively, with one of these patients experiencing transient diabetes insipidus. The remaining patient with a hypothalamic craniopharyngioma underwent complete resection with obligatory panhypopituitarism and diabetes insipidus. CONCLUSION: Endoscopic endonasal transposition of the pituitary gland and its stalk can provide a valuable corridor to the retroinfundibular space and interpeduncular cistern with pituitary function preservation in the majority of patients. This approach should only be pursued once significant experience with endoscopic endonasal approaches has been acquired.

Intracranial epidermoid cyst: case report.

Intracranial epidermoid cysts are estimated to constitute 0.2 to 1.8% of brain tumours (4) and they can be divided into four categories describing their anatomic origin and frequent primary location: retro-sellar-cerebellopontine angle, parasellar-sylvian fissure, suprasellar-chiasmatic and basilar-posterior fossa. We describe an unusual case of pre-pontine epidermoid cyst arising in the temporal lobe and in inter-peduncles cistern: development and surgical treatment are discussed.

Primary intracranial hydatid cyst in the interpeduncular cistern.

Cerebral involvement in hydatid disease occurs in 1-4% of cases. There are few documented cases in the literature of intracranial hydatid cysts in unusual locations such as pons and thalamus. In this report, a case of 33-year-old male with primary intracranial hydatid cyst in the interpeduncular cistern is reported. This is the first such case in the literature.

Status dissociatus after surgery for tegmental ponto-mesencephalic cavernoma: a state-dependent disorder of motor control during sleep.

After surgery for a tegmental ponto-mesencephalic cavernoma, a patient developed sleep-related excessive fragmentary myoclonus, diffuse myoclonic jerks, simple quasipurposeful movements of the limbs, and rapid eye movement (REM) sleep behaviour disorder as motor features of status dissociatus, a condition in which elements of one state of being (wake, NREM and REM sleep) pathologically intrude into another.

Syringocephaly.

Syringomyelia is associated with Arnold-Chiari Type I malformations. Syringobulbia describes the phenomenon of syrinx extension into the brain stem. Syringocephaly is the further dissection of the fluid-filled cavity into the cerebral peduncles and cerebrum. In this case report, we describe a patient who presented with bulbar, sensory, motor, and coordination deficits both ipsilateral and contralateral to the lesion. This is most likely attributable to the wandering course the syrinx takes as it dissects through the spinal cord and into the internal capsule. This ill-defined syrinx disrupts various nuclei and fasciculi, both pre- and post-decussation, thus explaining the multiple deficits on each side. We initially treated this patient with a suboccipital craniectomy, C1 laminectomy, and duraplasty, which mildly improved his deficits. During follow-up, the patient was then found to have an exacerbation of his symptoms, at which time we performed a VP shunt revision (the patient had a history of hydrocephalus treated by a functioning VP shunt). Approximately 2 weeks after revision of the VP shunt, the patient had worsening of his symptoms, which we treated with a syringopleural shunt. This proved to be the most effective treatment with the greatest clinical improvement. Several months later, however, the patient died secondary to pulmonary disease exacerbated by VP shunt infection. In this paper, we also review the literature regarding the formation and treatment of syringocephaly, a rare and poorly understood entity.

Impairment of two-way active avoidance after pedunculopontine tegmental nucleus lesions: effects of conditioned stimulus duration.

It was investigated whether the disruptive effects of bilateral lesions of the pedunculopontine tegmental nucleus on two-way active avoidance might vary depending on variations of task demand. The animals were either subjected to bilateral electrolytic lesions of the pedunculopontine tegmental nucleus (Lesion groups) or were sham-operated (Control groups). All the rats were subjected to two 30-trial sessions of two-way active avoidance (separated by ten days), using either a 10-s conditioned stimulus (low task demand) or a 3-s conditioned stimulus (high task demand). The lesions induced a significant disruption of two-way active avoidance in the two conditions tested, but, in both lesioned and control rats, the number of avoidance responses was higher when the 10-s conditioned stimulus was used. In lesioned animals, the condition of high task demand was associated with a significant increase of escape failures. Lesions did not affect locomotor activity during the period of adaptation to the conditioning apparatus, but induced training-specific motor deficits (a decrease of intertrial crossings and an enhancement of escape latencies) regardless of the specific training conditions used. The results are discussed in terms of the influences of the pedunculopontine tegmental nucleus in thalamocortical and striatal systems.

The role of the pedunculopontine tegmental nucleus in experimental parkinsonism in primates.

To clarify the role of the pedunculopontine tegmental nucleus (PPN) in motor behavior, we have conducted a series of experiments in primates. In the first part, PPN was damaged locally with kainic acid, which resulted in mild hemiparkinsonism in the contralateral limbs. In the second part, muscimol (a GABA agonist) was locally injected into the PPN area in monkeys who had been trained to perform a lever-pull movement with an arm, resulting in a slowness of movement and a delay of the movement onset. In the third part, a dopaminergic neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was systemically injected in monkeys with prior PPN lesioning. These monkeys developed no, or if any, very mild parkinsonism. PPN lesioning was supposed to have protected the nigral neurons from the MPTP- toxicity. The PPN facilitates the motor system through its nigral projection. The decreased activity of the PPN may underlie the pathophysiology of parkinsonism.

Lesions of the pedunculopontine tegmental nucleus increase sucrose consumption but do not affect discrimination or contrast effects.

Pedunculopontine tegmental nucleus (PPTg) lesions block place preferences to drugs or food only when animals are nondeprived. PPTg lesions also disrupt operant responding, but lesioned rats cannot discriminate active from inactive levers. It is not clear, therefore, whether PPTg lesions block reward or disrupt the ability to differentiate changes in reward magnitude. These hypotheses were tested by measuring sucrose consumption, choice, and contrast effects after PPTg lesions. Both sham and lesioned rats consumed greater amounts of a sucrose solution as the concentration and level of deprivation were increased. Given a choice between 2 solutions, all rats consumed more of the higher concentration. Both groups exhibited contrast effects when the concentration was shifted from 32% to 4% within a session. Somewhat surprisingly, lesions increased sucrose intake when rats were food-restricted. These results suggest that PPTg lesions do not disrupt primary motivation or the ability to evaluate and respond to changes in reward strength.

Long-lasting increase in anxiety after electrolytic lesions of the pedunculopontine tegmental nucleus.

This study examined the effect of electrolytic lesions of the pedunculopontine tegmental nucleus (PPTg) on emotionality in rats. Rats with PPTg or sham lesions were tested in the elevated plus-maze, the social interaction test, the open-field test, and the conditioned fear paradigm. Histology showed that lesions were concentrated on the caudal half of the PPTg. In the plus-maze, behavioral scores were biased toward increased "anxiety" on the 1st testing day. Five consecutive exposures to the apparatus led to marked habituation in sham-lesioned but not in PPTg-lesioned rats. On the 5th day, most indexes of emotionality indicated elevated anxiety in PPTg-lesioned rats. Increased anxiety was also found in PPTg-lesioned rats in the social interaction test. In the conditioned fear paradigm, movement suppression during the postconditioned stimulus period was found in both groups on the 1st day of extinction but only in PPTg-lesioned rats on the 2nd extinction day, indicating extinction was slower in PPTg-lesioned rats. Lesions of the caudal PPTg appear to produce long-lasting anxiety in rats.

Nicotine affects the occipital theta rhythm after lesion of the pedunculopontine tegmental nucleus in rats.

The pedunculopontine tegmental nucleus (PPTg) is assumed to be one of the brainstem sites for eliciting the theta rhythm that is expressed in rat hippocampal and occipital EEG in high arousal states. Unilateral lesions of the PPTg in rats induced a hemispheric asymmetry in the expression of occipital theta waves during exploratory sniffing with a significantly lower mean power in the lesioned hemisphere. Acetylcholine was found to be the main neurotransmitter used by the PPTg neurones. Therefore, the present study was conducted to determine if nicotine was effective in counteracting the lesion-induced hemispheric asymmetry of the theta waves in the occipital EEG of freely moving rats. In 12 rats the PPTg was unilaterally lesioned by ibotenic acid. The occipital EEG was recorded from both hemispheres in three waking states and after intraperitoneal nicotine and physostigmine application. Nicotine reversed the lesion-induced hemispheric asymmetry of the theta rhythm during exploratory sniffing in a dose-dependent manner. Physostigmine did not reverse the hemispheric asymmetry of the theta waves. The present study indicates that a nicotinic component may be involved in the reinforcement or elicitation of the theta rhythm by the pontomesencephalic tegmentum.

Hemianopic visual field defects in children with intracranial shunts: report of two cases.

OBJECTIVE AND IMPORTANCE: Intracranial shunts are commonly placed in children and frequently require replacement during the child's growing years. Severe signs of increased intracranial pressure often are the first indication of shunt displacement and malfunction. Subtle neuro-ophthalmic signs in children are usually overlooked. CLINICAL PRESENTATION: Two cases are described in which homonymous hemianopsia resulted from unsuspected movement of the shunt catheter in growing children. In one male patient, the catheter tip impaled the optic tract, and in the other male patient the shunt became embedded in the midbrain tegmentum and shunt failure led to compression of the posterior cerebral artery. INTERVENTION: In the presence of optic atrophy, papilledema may go unnoticed without serial examinations. This stresses the importance of detecting other early warning signs of shunt displacement and increased intracranial pressure, including visual field changes and subtle abnormalities of motility. CONCLUSION: Because early diagnosis and shunt revision may allow visual recovery, children with shunts should be followed with visual fields and serial disc photographs.

Pediatric midbrain tumors: a benign subgroup of brainstem gliomas.

The presentation, radiographic findings and course of 17 children with MRI-documented intrinsic midbrain lesions are reviewed. The anatomic centers of all the lesions were tectal, peritectal, or tegmental. Lesions centered at the pineal gland were excluded. Signs of increased intracranial pressure from hydrocephalus requiring shunt placement were present in 14 patients. Histopathological diagnosis was confirmed in three tumors; these were low grade astrocytomas and all received focal irradiation, as did one unbiopsied tumor. The remaining 13 patients with no histopathological diagnosis received no therapy other than shunt placement in 11. All but one of the lesions have remained clinically and radiographically stable, with a 4-year progression-free and total survival of 94 and 100%, respectively. We conclude that mass lesions originating in the upper midbrain are a subset of intrinsic brainstem tumors with a relatively benign course, usually presenting with hydrocephalus after infancy. They may remain stable for considerable periods and may require no further therapy after treatment of hydrocephalus. Surgical biopsy and/or resection can usually be reserved for progressive or atypical lesions which may also require further adjuvant therapy.

Subthalamic nucleotomy alleviates parkinsonism in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-exposed primate.

Research into the neural mechanisms underlying the symptoms of parkinsonism utilizing the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-exposed primate model have shown that the subthalamic nucleus (STN) occupies a central role. As a logical development of this theory, we have studied the effects of thermocoagulative lesions of the STN in the primate model. Such lesions can cause remarkable symptom reversal in the experimental primate model.

Regional effects of apomorphine on rat brain cholecystokinin-8 like immunoreactivity following electrolytic lesions of the ventral tegmental area.

After bilateral electrocoagulation of the ventral tegmental area (VTA) of rats, apomorphine (APO) was administered intraperitoneally to study the effect on the cholecystokinin-8 like immunoreactivity (CCK-8 IR) in the medial prefrontal cortex, the anterior and posterior part of the nucleus accumbens and the corpus striatum. In the medial prefrontal cortex and the posterior part of the nucleus accumbens, CCK-8 IR was markedly decreased by lesioning of the VTA. Then recovery of CCK-8 IR was noted in the APO treated rats following electrolytic lesioning of the VTA. This recovery corresponds to the response of CCK neurons not originating in the VTA or CCK interneurons to APO via DA receptors. In the anterior part of the nucleus accumbens and the corpus striatum, no significant decrease in CCK-8 IR was noted even following lesioning of the VTA. APO administration following the lesioning, however, resulted in a marked increase in CCK-8 IR in the anterior part of the nucleus accumbens and the corpus striatum. According to this result, in these sites, very few CCK neurons originating in the VTA exist and CCK neurons originating in sites other than the VTA or CCK interneurons react on APO via DA receptors.