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EDITORIAL
Year : 2010  |  Volume : 58  |  Issue : 5  |  Page : 683-684

Idiopathic intracranial hypertension: Are false localising signs other than abducens nerve palsy acceptable?


Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India

Date of Web Publication28-Oct-2010

Correspondence Address:
Kurupath Radhakrishnan
Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum - 695 011, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.72160

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How to cite this article:
Menon RN, Radhakrishnan K. Idiopathic intracranial hypertension: Are false localising signs other than abducens nerve palsy acceptable?. Neurol India 2010;58:683-4

How to cite this URL:
Menon RN, Radhakrishnan K. Idiopathic intracranial hypertension: Are false localising signs other than abducens nerve palsy acceptable?. Neurol India [serial online] 2010 [cited 2019 Nov 21];58:683-4. Available from: http://www.neurologyindia.com/text.asp?2010/58/5/683/72160


Idiopathic intracranial hypertension (IIH) is possibly encountered more frequently now a days than in the past years in accordance with the current epidemic of obesity. Till recently, the term pseudotumour cerebri was used synonymously with IIH. While pseudotumor cerebri could be due to multiple causes including intracranial sinus-venous thrombosis, the term IIH should be restricted to patients in whom all causes of intracranial hypertension have been excluded. [1],[2] The currently proposed diagnostic criteria for IIH require the presence of (a) symptoms and signs of increased intracranial pressure (ICP) in an awake and alert patient; (b) no localising neurological signs, other than unilateral or bilateral sixth nerve paresis; (c) documented cerebrospinal fluid (CSF) opening pressure of ≥250 mm of water, but a normal composition of CSF, except for decreased CSF protein level; (d) no evidence of hydrocephalus, mass lesion or intracranial sinus-venous thrombosis on magnetic resonance imaging (MRI) and MR venography; and (e) every other cause of intracranial hypertension excluded. [2]

The typical patient with IIH is an obese but otherwise healthy woman of the childbearing age. [1] In a population-based sample of 81 IIH patients (76 females and 5 males), the age at presentation was in the range 8-55 years (mean, 28.6 years). [3] An atypical patient is a child or a man, or an elderly or thin individual, all distinctly uncommon profiles of IIH wherein hidden causes of increased ICP need to be excluded with certainty. In a case-control study, the symptoms most frequently reported by IIH patients were headache (94%), transient visual obscuration (68%), pulsatile tinnitus (58%), photopsia (54%), diplopia (38%), vision loss (30%), and retrobulbar pain on eye movements (22%). [4]

The sign of IIH is papilloedema with its resultant vision loss. [1] Although it is usually bilateral, unilateral and highly asymmetric papilloedema [5] has been documented in IIH. [1] Thus, it is important to recognise this association because it indicates that the fluid dynamics between the intracranial and subarachnoid space of the optic nerve need not necessarily be bi-directional and bilaterally symmetrical. Papilloedema may be absent in about 6% of IIH patients with proven IIH. [1] Mean CSF opening pressure, although above normal, has also been found to be lower in these patients compared with those with papilloedema. [6] On the other hand, rapid visual deterioration associated with florid papilloedema, also described as "fulminant" or "malignant" IIH, necessitates emergent surgical treatment. [7]

Abducens nerve palsy, either unilateral or bilateral, is the only currently accepted false localising sign in IIH. It is seen in about one-third of patients. [1],[2] Other patterns of ophthalmoplegia such as transient or established pupillary-sparing third nerve palsy, fourth cranial nerve palsy, internuclear ophthalmoplegia, skew deviation, and diffuse bilateral ophthalmoplegia have been described in isolated case reports of patients with presumed IIH, but are sufficiently atypical to raise concern of some other causes of intracranial hypertension. [1] A report by Rezazadeh and Rohani [8] a patient with IIH and third nerve palsy warrants sufficient attention, considering the presence of normal ancillary investigations including angiography and demonstration of pupillary involvement. The probable mechanism of third nerve (and other cranial nerves) involvement seems to be compression in the subarachnoid space in the setting of raised ICP. A reversal of the oculomotor palsy following serial lumbar punctures establishes its relation to raised ICP. While the authors have excluded all other causes, an autoimmune evaluation is mandatory, as conditions like systemic lupus erythematoses (a known cause of pseudotumour cerebri) can manifest similarly. Involvement of the fifth and seventh nerves has been recorded in the context of IIH. [1] Children with intracranial hypertension secondary to steroid administration or following infections like mycoplasma, have demonstrated signs that suggest a posterior fossa lesion, including ataxia, facial palsy, nuchal rigidity, malaise, irritability, torticollis, or Babinski sign. [1] Another interesting false localising sign of raised ICP is extensive radiculopathy, leading to areflexic quadriparesis mimicking Guillain-Barrι syndrome associated with intracranial sino-venous thrombosis. [9] These associations again emphasise the need to be vigilant while dealing with atypical presentations of IIH.

With advances in neuroimaging techniques and a growing understanding of the pathophysiology of IIH, it is mandatory to exclude other causes of increased ICP without ventriculomegaly or mass lesions, such as gliomatosis cerebri, meningitis, and intracranial sino-venous thrombosis, which may not have computed tomography abnormalities. No clinical or auxillary findings help to differentiate intracranial sino-venous thrombosis from IIH, except for female gender and lower CSF protein level. [2] MR venography (preferably gadolinium-enhanced) is currently the study of choice. The use of this modality has revealed that the reported incidence of IIH might only be the tip of the iceberg, as many cases present, as headache without papilloedema and such cases could be potentially misdiagnosed as other headache syndromes. A recent prospective study utilised MR venography in 724 patients with recurrent headaches. [10] Of these, 49 patients (6.7%) had bilateral transverse sinus stenosis. Further, of the 49 patients, 28 underwent lumbar puncture and 19 (67.8%) were found to be suffering from IIH. Besides narrowing or stenosis of dural/cortical veins, other MRI signs include flattening of the posterior sclera, vertical tortuosity and elongation of the optic nerve, distension of the perioptic subarachnoid space and partially empty sella and these have been found to be reversible. [11] Although these MRI signs lack sensitivity in diagnosing IIH, a combination of signs in the context of a clinical picture is helpful.

There is thus a renewed interest in the unusual clinical and radiological manifestations of IIH. This basically reflects our currently nascent knowledge of an ostensibly understood disorder. It is evident that more atypical findings are bound to be reported, which could contribute to understanding the pathogenesis and treatment of IIH. Although false localising signs deviate the clinician away from the diagnosis of IIH, it may be considered after utilising the appropriate gamut of investigations to exclude other causes of increased ICP.

 
  References Top

1.Radhakrishnan K, Ahlskog JE, Garitty JA, Kurland LT. Idiopathic intracranial hypetension. Mayo Clin Proc 1994;69:169-80.  Back to cited text no. 1
    
2.Sylaja PN, Moosa NV, Radhakrishnan K, Sarma PS, Kumar SP. Differential diagnosis of patients with intracranial sinus venous thrombosis related isolated intracranial hypertension from those with idiopathic intracranial hypertension. J Neurol Sci 2003;215:9-12.  Back to cited text no. 2
    
3.Radhakrishnan K, Thacker AK, Bohlaga NH, Maloo JC, Gerryo SE. Epidemiology of idiopathic intracranial hypertension: A prospective and case-control study. J Neurol Sci 1993;116:18-28.  Back to cited text no. 3
[PUBMED]    
4.Giuseffi V, Wall M, Siegel PZ, Rojas PB. Symptoms and disease associations in idiopathic intracranial hypertension (pseudotumor cerebri): A case-control study. Neurology 1991;41:239-44.   Back to cited text no. 4
[PUBMED]    
5.Wattamwar PR, Baheti NN, Radhakrishnan A. Idiopathic intracranial hypertension presenting as unilateral papilledema. Neurol India 2010;58:818-9.  Back to cited text no. 5
  Medknow Journal  
6.Digre KB, Nakamoto BK, Warner JA, Langeberg WJ, Baggaley SK, Katz BJ. Comparison of idiopathic intracranial hypertension with and without papilledema. Headache 2009;49:185-93.  Back to cited text no. 6
    
7.Thambisetty M, Lavin PJ, Newman NJ, Biousse V. Fulminant idiopathic intracranial hypertension. Neurology 2007;68:229-32.  Back to cited text no. 7
[PUBMED]  [FULLTEXT]  
8.Rezazadeh A, Rohani M. Idiopathic intracranial hypertension with complete oculomotor palsy. Neurol India 2010;58:820-21.  Back to cited text no. 8
  Medknow Journal  
9.Moosa A, Kishore A, Gupta AK, Radhakrishnan K. Blindness, ophthalomoplegia and extensive radiculopathy: An unusual clinical syndrome in intracranial sinovenous thrombosis. Neurol India 2004;52:96-8.  Back to cited text no. 9
[PUBMED]  Medknow Journal  
10.Bono F, Messina D, Giliberto C, Cristiano D, Broussard G, Fera F, et al. Bilateral transverse sinus stenosis predicts IIH without papiloedema in patients with migraine. Neurology 2006;67:419-23.  Back to cited text no. 10
[PUBMED]  [FULLTEXT]  
11.Suzuki H, Takanashi J, Kobayashi K, Nagasawa K, Tashima K, Kohno Y. MR imaging of idiopathic intracranial hypertension. AJNR Am J Neuroradiol 2001;22:196-9.  Back to cited text no. 11
[PUBMED]  [FULLTEXT]  



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