B ritish Journal of Neurosurgery 1999;13(5):500± 503 SHORT REPORT Peduncular hallucinosis: an unusual sequel to surgical intervention in the suprasellar region R. KUMAR, S. BEHARI, J. WAHI, D. BANERJI & K. SHARMA Departments of Neurosurgery and Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India Abstract Peduncular hallucinations are formed visual images often associated with sleep disturbance, and are caused by lesions in the midbrain, pons and diencephalon. In the present study, we report two patients who developed peduncular hallucinations following surgery in the suprasellar region. In one of these, the peduncular hallucinations were a sequele to endoscopic third ventriculostomy, while in the other, they were due to diencephalon and mid-brain compression by a postoperative clot following excision of a hypothalamic astrocytoma. Key words: Peduncular hallucinosis, visual hallucinations, suprasellar astrocytoma. Introduction fu ndoscopy showed bilateral secondar y optic atrophy. She also had bilateral abducent paresis Peduncular hallucinations are formed, coloured, visual and gait ataxia. images.1 They have been reported in vascular and Computed tomography (CT) revealed aqueductal infective lesions2± 4 of the thalamus,5 the pars reticu- stenosis, and dilated lateral and third ventricles with lata of the substantia nigra,1 midbrain,6 pons7 and periventricular lucency.Therefore, an endoscopic third basal diencephalon,8 as well as by extrinsic compres- ventriculostomy was perform ed to relieve the sion of the midbrain.9 We report the occurrence of hydrocephalus. The rigid endoscope was negotiated peduncular hallucinosis in two patients after endo- via a right frontal burr hole, through the lateral scopic third ventriculostomy in one, and to dien- ventricles and the foramen of Monro. Holes were cephalon and m idbrain com pression by a made in the third ventricular ¯ oor just anterior to the postoperative clot that developed following surgical mamillary bodies to establish a communication excision of a hypothalamic astrocytoma in the other. between the third ventricle and basal cisterns. Post- The pertinent literature is reviewed. operatively, the patient remained drowsy, but was To the best of our knowledge, peduncular halluci- obeying simple commands. She started having formed nosis occurring after an endoscopic third ventriculos- tomy has not previously been reported. visual hallucinations, where occasionally she would start talking to an imaginary dog and, at other times, she imagined that she was in a classroom talking to Case report her teacher. A repeat CT on the third postoperative day revealed bilateral subdural hygrom a. The Case 1 ventricular size had decreased considerably indicating An 11-year-old girl presented with a 6-month history a functioning ventriculostomy (Fig. 1). Following of impaired memory and gait ataxia. Four months drainage of the hygroma through bilateral frontal burr prior to admission, she was having progressive holes, her level of consciousness improved. She bilateral visual loss. T here was no history of became alert and started responding to commands headache, vomiting, seizure or unconsciousness. briskly, but the formed visual hallucinations persisted. N eurolog ical exam ination revealed that she She had a disturbed sleep rhythm, would remain had im paired shor t-term m em ory. Her visual awake during the night and nocturnal visual hallucina- acuity was 1/60 in the right eye, 6/24 in the left and tions were more frequent. The hallucinations Correspondence: Dr Raj Kumar Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow- 226014 , Uttar Pradesh, India. Tel: 91 (522) 440700/4400/04± 8, Extn 2157 (Office) & 2158 (Residence), Fax: 91 (522) 440973 /440017. Email: [email protected] Received for publication 5th May 1998. Accepted 26th June 1998. ISSN 0268± 8697 print/ISSN 1360-046 X online/99/050500± 04 ½ The Neurosurgical Foundation Peduncular hallucinosis 501 FIG. 1. Case 1: postoperative CT scan showing bilateral subdural collection with signi® cant decompression of ventricular systems (in comparision to preoperative CT scan). FIG. 2. Case 2: enhanced CT scan showing a hypodense spontaneously subsided gradually over the next 2 hetrogenous m ass with specks of calci® cation, non-enhancing on contrast in sellar-suprasellar region with weeks. hydrocephalus. At follow-up of one-and-a-half months, she was well orientated, alert and asymptomatic. At 10 months follow-up her vision had improved to 6/60 in right Tumour excision was performed by a bifrontal eye and 6/18 in left eye. craniotomy and interhemispheric, lamina terminalis approach.The tumour was vascular, could be partially Case 2 aspiraled and displayed calci® cation.The optic nerves A 10-year-old girl presented with bilateral headache and chiasma were decompressed and the tumour and episodic bouts of vomiting for 7 months. There extension into the third ventricle and retrosellar was partial improvement in headache following regions were removed. Postoperatively, the patient vomiting after starting glycerol and acetazolamide. remained drowsy though she followed simple She also complained of bilateral visual deterioration commands, moving her limbs spontaneously and for three months that had progressed to interfere symmetrically. Repeat CT revealed an operative site with her scholastic performance. On examination, haematoma with persistent hydrocephalus (Fig. 3). she was conscious and oriented with bilateral visual As the patient’s neurological status did not further acuity of 6/24, normal fundi, left homonymous hemi- deteriorate, no attempt was made to evacuate the anopia and right superior temporal quadrantopia. Her haematoma and only an external ventricular drainage sleeping pulse rate and urine output were normal, was instituted, which was subsequently converted into and there were no signs of overt endocrinopathy. Her a right ventriculoperitoneal shunt on the ® fth laboratory investigation including serum and urine postoperative day following resolution of the haemor- osmolality and hormonal pro® le were within normal rhagic ventricular cerebrospinal ¯ uid. She also limits. developed a mild, transient diabetes insipidus, which CT revealed a hypodense mass with specks of did not require any antidiuretic hormone therapy. calci® cation, non-enhancing on contrast, in the sellar- Following placement of the external ventricular suprasellar region, with hydrocephalus (Fig. 2). MRI drainage, the patient became orientated and started revealed a sellar and suprasellar mass, hypointense responding briskly to commands. However, she on T1- and hyperintense on T2-weighted images. It started having visual hallucinations. She acted as if reached to the third ventricle and displaced the she was being slapped by her father, she talked to her chiasma inferiorly. There was retrosellar extension imaginary friends and reported seeing birds and an into the interpeduncular and prepontine cisterns. angel in the room. Her anxiety and restlessness were 502 R. Kumar et al. The clinical syndrome of `peduncular hallucinosis’ consists of formed, vivid, visual hallucinations.These hallucinations are highly coloured, mobile and are composed of concrete, often animate objects. These are not stereotyped and vary from one occasion to the next, are more pronounced nocturnally and are often associated with disordered sleep. This was specially seen in our ® rst case. These visual hallucinations may be of two types. In one, the hallucinations are often detached from the patient’s own thoughts and actions, and thus are not mistaken for reality; in the other, which were seen in our second case, the hallucinations are mistaken for reality and are associated with agitation and delu- sion.4,10,12,15 Peduncular hallucinations occur in the brainstem and diencephalon region in the setting of vascular stroke,3 ,1 3 ,14 encephalitis,2 intoxication1 2 ,1 5,1 6 following vertebral angiography3 and by transient brainstem compression.9 The aetiology of the hallucinations in peduncullar hallucinosis is unknown. Van Bogaert stated that peduncular hallucinations are a state of ego dissolutions with the loss of the ability to distinguish external reality from imagina- FIG. 3. Case 2: plain CT scan showing an operative site tion.11 haematoma with persistent hydrocephalus. Damage to the ascending reticular activating controlled by a mild tranquilizer and by the end of system4± 6,14 has also been proposed to result in these week, the hallucinations had spontaneously subsided. hallucinations. Mackee et al. have suggested that Histopathology of the tumour tissue showed it to occlusion of the presenting paramedian branches of by an astrocytoma. At discharge and at subsequent the rostral basilar artery causes infarcts in the medial follow-up at 3 months, she remained asymptomatic. diencephalon especially pars reticulata of the There was subjective improvement in her visual acuity substantia nigra, and brain stem tegmentum.1 These and signi® cant reduction in the ® eld defect. regions are also connected to the pedunculopontine nuclei by efferent pathways.17± 19 Lesions in these Discussion regions produce disordered REM sleep that is linked 1,20 In 1922, L’ hermitte described the clinical syndrome to dreams. Thus, peduncular hallucinations are of visual hallucinations in a 72-year-old woman who due to release of dream activity that is normally 21 developed headache, vomiting and vertigo, followed suppressed during wakefulness. Evidence