H Foyaca-Sibat, L Ibañez-Valdés
dysphagia, electrocardiographic changes, epilepsy, insular epilepsy, insular lobe, neurocysticercosisncc, neurogenic heart
H Foyaca-Sibat, L Ibañez-Valdés. Insular Neurocysticercosis: Our Findings And Review Of The Medical Literature. The Internet Journal of Neurology. 2005 Volume 5 Number 2.
Fourty six patients with radiographically proven NCC primarily involving the right insula lobe, the left insular lobe or both, attending to neurocysticercosis clinic and/or neurology clinic at Umtata General Hospital or Nelson Mandela Academic Hospital (South Africa) between January 1999 and January 2005 were selected for this study. All patients were assessed for neglect, dysphagia, dysphasia, cardiac disturbances and insular epilepsy among other disorders. CT scan, Elisa test for cysticercosis, ECG, and EEG tests were done.Commonest problems found were functional dysphagia, visual and somesthetic neglect, neurogenic heart, ECG abnormalities such as: ST segment depression and QT interval prolongation. Insular epilepsy was characyterized by laryngeal discomfort, thoracic oppression, unpleasant paresthesia, and sensation of levitation. Similar findings about insular NCC were not reported before.Insular neurocysticercosis should be listed among causes of sudden death, SUDEP, and neurogenic heart.
One day, somebody asked to our medical students: “How large of the different lobes of the brain relative to each other?” And the most advantaged one answered: “The percentages of total cerebral cortex volume for the different lobes are: frontal lobe = 41%, temporal lobe = 22%, parietal lobe = 19%, and occipital lobe = 18%” therefoe he answered correctly 1 but as you can see many peoples refer to cerebral lobes as: frontal, parietal occipital and temporal. Nevertheless, in addition to these four lobes, a fifth one exists called the insular lobe (IL ) the IL or the island of Reil was first referred to by Vic d'Azyr in 1786 as the “circonvolutions situated between the sylvian fissure and the corpus striatum” 2 the first description was done by j. C. Reil in 1809 and further detailed anatomic descriptions of this structure were made independently by Guldberg and Eberstaller in 1887 3 . Remembering the lost island of Atlantis this lobe remains hidden and lies submerged beneath the parietal, frontal, and temporal opercular cortices, buried under a tangled web of middle cerebral artery branches.IL is internal and is not visible from the surface of the brain, its the best protected region of the whole cerebral cortex, and the poorest studied region all over brain; IL represents a remarkable challenger for further researchers among new generations of neurologists, neurophysiologists, neuroinmunologists, and neuropathologist among others 3 . Some functions of the right insular lobe are little bit known such as its role in taste perception its intensity and recognition for the ipsilateral tongue (rostrodorsal insula) and some fuctions of the left insular cortex for intensity of the stimulus ipsilateral to the tongue and taste recognition bilaterally, 4 gustatory mechanism, movements of the mouth, and oropharyngeal swallowing (anterior insular) 5 are not well known neither, and almost nothing has been demonstrated about the role of insular lobe over the amygdala complex and emotional behavior.
The human IL is also considered as paralimbic cortex, because of its connections with limbic and sensorimotor cortices, the IL is believed to play a role in affective and attention aspects of human behaviour as well. Paralimbic insular regions have functional specialization for behaviours requiring integration between extra personal stimuli and the internal milieu. Based on these connections, one might expect that lesions of the insular cortex may result in disorders of neglect 6 . This was recently observed in a right-handed individual who developed severe multimodal neglect after injury to the right insular lobe, adjacent white matter, and the inner face of the overlying operculum 7 .
The incidence of neglect in patients with isolated insular infarctions due to ILNCC has not been previously investigated 8,9,10,11,12 Previous studies showed greater severity of somesthetic, audition, and visual neglect among patients with right compared with left insular damage. These findings are consistent with anatomic connections that have been identified between insular cortex and various cortical regions from animal studies. 13,14
The present findings also provide empirical support for observations of neglect associated with right insular infarction reported in case studies. 8
Scant information is available about the role of the human insular cortex in cognitive processes. Altered behavior following insular damage in humans has previously been described in case reports and associations between right insular lobe damage and neglect 8 and left insular damage and aphasia 15,16 have also been reported. Berthier et al 12 reported the case of a right-handed patient who, after an ischemic infarction that involved the entire right insular cortex and adjacent white matter, developed a severe neglect syndrome, oral apraxia, mutism, and ideomotor apraxia on the right hand.
Although the presence of neglect is usually considered a sign of parietal lobe dysfunction, it should not be surprising to find neglect in association with non-parietal lesions. A review of neglect syndromes in monkeys and humans suggests that several regions provide an integrated network for the mediation of directed attention. 2 The 3 cortical components of this network are the posterior parietal lobe, frontal eye fields, and the cingulate gyrus. Heilman et al 10 have described a neuroanatomic system involving cortical-limbic-thalamic-reticular components that lead to preparatory activation or arousal toward meaningful stimuli in the contra lateral hemi space. In humans, neglect is most commonly associated with lesions that involve the right inferior parietal lobe, which includes Brodmann's areas 40 and 39. However, there are other areas where lesions in humans have been reported to induce neglect, including the dorsolateral frontal lobes, the mesial frontal lobes including the cingulate gyrus, and the thalamic and mesencephalic reticular formation. 1 Moreover, several reports have clearly shown that lesions elsewhere in the right hemisphere may result in neglect. 12,16
Although clinical descriptions of cases with restricted insular lesions are rare, insular anatomy, connectivity, and physiology have been extensively studied in monkeys and humans 18 . The insular lobe sends neural efferent to cortical areas, from which it receives reciprocal afferent projections. Considering both afferents and efferent, the insular lobe has connections with principal sensory areas in the olfactory, gustatory, somesthetic (SI and SII), and auditory (AI and AII) modalities as well as the paramotor cortex (area 6 and perhaps MII), polymodal association cortex, and a wide range of paralimbic areas in the orbital, temporo-polar, and cingulate areas.
It should also be noted that the insular cortex has reciprocal connections with the anterior inferior parietal cortex, that produces classical parietal neglect when damaged. On the basis of the above data and anatomic connections, the present finding might be construed to indicate that insular lesions probably disrupt connections with areas that are normally involved in arousal, attention, and activation. Right insular damage, similar to right parietal lobe damage, may impair awareness of external stimuli and lead to neglect.
Neurocisticercosis (NCC) is a parasitic infection of central nervous system (CNS) caused by the larval stage (Cysticercus cellulosae) of the pig tapeworm Taenia solium. This is the most common helminthes to produce CNS infection in human being. The larvae of Taenia solium (
Material And Method
Fourty six patients with radiographically proven NCC primarily involving the insula,attending to neurocysticercosis clinic and/or neurology clinic at Umtata General Hospital or Nelson Mandela Academic Hospital (South Africa) between January 1999 and January 2005 were included in the study. The study consisted of a prospective analysis. Patients who could be included in this prospective group were identified on admission to the hospital and underwent a detailed evaluation. Once accepted into the study, subjects were scheduled for a subsequent visit for a computerized tomography (CT) scan of the brain, if the CT was confirmatory, they were evaluated both clinically and radiologically at each review visit. The serum from each patient was tested for cysticercus antibodies by enzyme linked immunosorbent assay (ELISA). For most of the patient a routine 12-lead electrocardiogram (ECG) was done. All patients underwent a full neurological examination with detailed seizure history. Dysphagia was confirmed when patients presented cough or swallowing disturbances after instillation of 5 ml of tap water into the mouth.
Impairment for recognition of fear or disguss on facial expression on selected photo were present in 2 patients but we were unable to confirm t therefore this aspect will not be considered for analysis.
Inter ictal EEG was performed in all epileptic patients: 28 males and 18 females. The mean duration of follow-up in the study was 27.8 (+/-20.86) months.
Commonest disturbances found in our serie are summarized in Table I, and medical reports about these issues are also reflected on that Table.In general, most relevant clinical manifestations from our serie were: neglect (n=6), disturbances of gustation (metallic taste as aura, n=4), functional dysphagia (n=8), cardiac asystole (n=3), signs of neurogenic heart (n=6), ECG abnormalities such as: Prolonged QT (QT interval in excess of 0.44 seconds) and ST depression (horizontal or down-sloping ST segment depression of 0.1 mV or more for 80 milliseconds),(n=4), ECG abnormalities were more commonly observed in patients presenting INCC on the right anterior or right posterior IL (Graphic 2) Disturbance of taste were confirmed almos exclusively in patients with INCC on the anterior left. (Table II)
Insular epilepsy was characterized by: pilomotor seizures (n=3), laryngeal discomfort and, thoracic oppression (n=3), unpleasant paresthesia, dysarthria and sensation of levitation without loss of concoiusness (n=3). Inter-ictal EEG done did not show remarkable abnormalities.
No significant correlation between INCC and Elisa for NCC was found. Dysphagia was observed in patients presenting NCC on the left IL (Table I) and most of those patients presented simple focal seizures (Graphic 1).
Calcified NCC on IL was confirmed only in epileptic patients (Figure 1) while CT showing active NCC in colloid or granular stages on the IL were found in patients presenting ECG abnormalities, neurogenic heart, SUDEP,neglect and dysphagia (Figure 2).
In our opinion, except epilepsy almost all neurologic manifestations to be discussed thereinafter arise from ILNCC when the encysted worm is on the way of death by natural cause or other conditions causing an irrititative/inflammatory response due to events such as: polarizing the immune response to Th2, suppressing interleukin 2, 5 and 6, and TH1 cytokine 24 . Increased IgG, interleukin-2-5 in serum and interleukin 5-6 plus neopterin in the CSF, accumulation and phenotype heterogeneity of mast cell with increased secretion of numerous powerful mediators such as endorphins, serotonine, histamine, heparin, kinins, leukotriens, prostaglandin, vasoactive intestinal peptide, proteolytic enzymes, cytokines and phospholipases which are well known to have significant pathophysiogical effects on vascular and neuronal tissues. among other problems
In 2004, Isnard et al 90 studied fifty patients performing video and stereoelectroencephalographic ictal recordings and direct electric insular stimulation of the insular cortex for presurgical evaluation of temporal lobe epilepsy and they found an ictal sequence of event in fully concious patients characterized by a sensation of laryngeal constriction and paresthesiae, often unpleasant, affecting large cutaneous territories, most often at the onset of a complex partial seizure (five of the six patients). It was eventually followed by dysarthric speech and focal motor convulsive symptoms. The insular origin of these symptoms was supported by the data from functional cortical mapping of the insula by using direct cortical stimulations and they concluded saying: “ This sequence of ictal symptoms looks reliable enough to characterize insular lobe epileptic seizures. Observation of this clinical sequence at the onset of seizures on video-EEG recordings in TLE patients strongly suggests that the seizure-onset zone is located not in the temporal but in the insular lobe; recording directly from the insular cortex should occur before making any decision regarding epilepsy surgery”. Other authors a year later were able to characterize insular onsets in the following set of symptoms—memorization of which may benefit all epileptologists. A fully conscious patient with laryngeal discomfort, dyspnea, unpleasant perioral or somatic paresthesias, and dysarthric speech, followed by somatomotor symptoms, implies an insular onset. The final proof is in the response to surgery. The authors provide both positive and negative evidence, that is, two patients who underwent only insular ablation were cured, whereas two who underwent only temporal ablation had persistent seizures 91 .
IENCC has not been well described before probable because little is known about insular seizures, because most of the symptoms and signs did not recall attention from patients and relatives, because these type of seizures are not very common and because other manifestations like disturbances of cardiac function, gastrointestinal symptoms, asociated behavioral disorders, and major complications including SUDEP are more relevant even for the attention of health professionals. We would like to enphasized that if these clinical features are not in mind, its diagnosis never going to be done. Based in our observations ILE can be differenciated from TLE if patients remains fully conscious during the attack but when epileptic activity spread from IL to temporal lobe or vice versa that clinical differentiation can be almost impossible to perform. If CT shows calcified NCC on the IL, final diagnosis can be supported by it(Figure 4)
A few weeks ago a comprehensive estimate of the monetary burden of cysticercosis in our region is published 92 obviously this interesting study did include IENCC and its desvastating consequences,Nevertheless, we hope after a better understanding of this problem more patients will be early diagnosed and the mortality rate due to NCC will be dramatically decreased contributing to alleviate poverty from this region.Insular neurocysticercosis should be listed among causes of sudden death, SUDEP, and neurogenic heart.