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Role of head and neck imaging in trigeminal neuralgia
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Role of head and neck imaging in trigeminal neuralgia




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Role of head and neck imaging in trigeminal neuralgia Role of head and neck imaging in trigeminal neuralgia Presentation Transcript

  • Role Of Head & Neck Imaging Preview In Patients With Trigeminal Neuralgia INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com 1
  • Contents • • • • • • • Course of Trigeminal nerve Trigeminal neuralgia History Clinical features Causes Diagn criteria Diff modalities of investigations www.indiandentalacademy.com 2
  • Trigeminal Nerve INFECTION & NEOPLASIA commonly www.indiandentalacademy.com Involve PERIPHERAL divisions (AJR 176,Jan 2001) 3
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  • Opthalmic branch www.indiandentalacademy.com 10
  • Maxillary Nerve • During its course- gives branches in 4 regions: Trigeminal N Maxillary 1. Middle cranial fossa • Middle Meningeal Nerve 2. Pterygopalatine fossa • Ganglionic • Zygomatic • PSA 3. Infraorbital groove & canal • MSA and ASA 4. On face • Inferior Palpebral • Lat/ Ext Nasal • Superior labial www.indiandentalacademy.com 11
  • Mandibular Nerve www.indiandentalacademy.com 12
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  • Subarachnoid Spaces/ Cisterns www.indiandentalacademy.com 14
  • Trigeminal Neuralgia • Also called tic douloureax • Distributed along 5th cranial nerve • As described by IHS: A painful, unilateral affliction of the face , characterized by brief electric shock lightening-like (lancinating) pain limited to distr. one or more div. of trigeminal nerve • 4 per 1,00,000 population www.indiandentalacademy.com 15
  • Trigeminal Neuralgia • • • • • >50 yrs > Women < Right side of face Pain is unilateral, most often in V2 & V3 Often misdiagnosed as dental pathology due to acute bouts of severe pain in the lower face evoked by perioral triggers, www.indiandentalacademy.com 16
  • • Bilateral Cases-3% • Division of involvement – Max - 66% - Mand - 49% - Opthal –16% - Both Max & Mand –19% - All 3 Divisions- 1% (Katusic et al -1990) www.indiandentalacademy.com 17
  • History • Aretaeus of cappadocia – at the end of 1st century - 1st clinical description of TN • John Locke in 1677 (american physician & philosopher) accurately identified clin features • Nicolaus Andre in 1756 – tic douloureux (painful jerking) • John fothergill in 1773- full & accurate description of TN {OOO medical management update, Vol. 100, No. 5 Nov 2005} www.indiandentalacademy.com 18
  • Etiopathogenesis • Focal demyelination at the site of compression may also allow electrical spread of excitation betwn. adjacent sensory axons (‘‘ephaptic’’ transmission). • An ephaptic short-circuit of this type within the trigeminal nerve might explain the sudden ‘‘electric’’ jolts of pain that characterize the disorder. {OOO 2005} • Central myelin replaced by - peripheral myelin. • Continued pulsatile pressure of the trigeminal nerve at the REZ may result in disordered conduction and “shortcircuiting” of impulses, producing trigeminal neuralgia {Robert et al, TN: MRI Features, Radiology 1989;172:767-70} www.indiandentalacademy.com 19
  • Sweet in 1967, diagnostic criteria for TN 1. 2. 3. 4. 5. The pain is paroxysmal. The pain may be provoked by light touch to the face (trigger zones). The pain is confined to the trigeminal distribution. The pain is unilateral. The clinical sensory examination is normal. www.indiandentalacademy.com 20
  • ICHD Criteria for Classical TN Classical Trigeminal Neuralgia: A. Paroxysmal attacks of pain lasting from a fraction of a second to 2 minutes, affecting one or more divisions of the trigeminal nerve and fulfilling criteria B and C: B. Pain has at least one of the following characteristics: 1. intense, sharp, superficial or stabbing 2. Precipitated from trigger areas or by trigger factors C. Attacks are stereotyped in the individual patient. D. There is no clinically evident neurological deficit. E. Not attributed to another disorder. www.indiandentalacademy.com 21
  • ICHD Criteria for Classical TN Symptomatic trigeminal neuralgia: A causative lesion, other than vascular compression, has been demonstrated by special investigations and/or posterior fossa exploration. • Symptomatic TN has the same key features of TN but results from another disease process (such as multiple sclerosis or a cerebellopontine angle tumor). • Symptomatic TN is defined by IHS as: ‘‘Pain indistinguishable from classic TN but caused by a demonstrable structural lesion other than vascular compression.’’ www.indiandentalacademy.com 22
  • Clinical evaluation Diagnosis is of TN is based on a • Clinical history of pain attacks that fit accepted diagnostic criteria supplemented by • Physical exam findings and • Cranial imaging studies. www.indiandentalacademy.com 23
  • Clinical examination • Head and neck examination. • The sensory examination: careful search for cutaneous or intraoral trigger zones in addition to areas of focal sensory loss. • In majority - sensory examination will be normal, • In some patients - mild tactile sensory deficit (hypesthesia) www.indiandentalacademy.com 24
  • Clinical examination • Because the facial (VII) and auditory (VIII) nerves lie adjacent to the trigeminal nerve in the cerebellopontine angle (CPA), they also deserve particular attention during the examination. • A patient with symptomatic TN resulting from a CPA mass will often also show subtle facial weakness and hearing loss on that side. www.indiandentalacademy.com 25
  • Physical examination • Physical examination findings are normal; • In fact, a normal neurologic examination is part of the definition of idiopathic TN. • Perform a careful examination of the cranial nerves, including the corneal reflex. • Abnormality suggests that the pain syndrome is secondary to another process www.indiandentalacademy.com 26
  • History • In the past, clinical symptoms & signs – accurate means • Assessment of the patient consisted of Computed tomography (CT) and Angiography. CT: has limited value in the evaluation of Posterior fossa & the Trigeminal nerve • Normal T. Nerve - not typically visualized. • Abnormalities along the expected course of the nerve. www.indiandentalacademy.com 27
  • History Angiography: more successful in predicting - causative vessel • Invasive & fails to show exact relationship bet Vess & N {Robert et al, TN: MRI Features, Radiology:1989;172:767-70} • Conventional biplane angiography • Intraarterial Digital substraction angiography (DSA) (quicker & requires smaller amounts of contrast medium Venous abnormalities - detected more easily- better contrast in the venous phase) {Radiology 1986;158:721-27} DSA AP www.indiandentalacademy.com Towns DSA Towns 28
  • MRI • Directly depicts the course of the cisternal portion of T. nerve. • All portions of the nerve from the REZ to the cavernous sinus can be more easily evaluated with MR imaging than with traditional modalities. • The possible impingement of neighboring vascular structures is also readily suggested. {Robert et al, TN: MRI Features, Radiology:1989;172:767-70} www.indiandentalacademy.com 29
  • MRI • Provides accurate information on – the anatomical location & – course of ectatic vessel in CPA & – the caused mass effect on the brainstem www.indiandentalacademy.com 30
  • MRA • MRA- a more recent imaging technique, allows visualization of the vascular anatomy of the relevant region without the use of contrast media. {Shahrokh C et al, JADA, Vol 135, 2004} • Allows evaluation of: Vessel Anatomy & Blood flow rates www.indiandentalacademy.com 31
  • Subarachnoid Spaces/ Cisterns Sagittal T2W MRI www.indiandentalacademy.com 32
  • PONS Axial T1W MRI www.indiandentalacademy.com 33
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  • Causes I. Typical/ Classical/ Idiopathic and Essential TN. Sec. to a vascular loop that compresses the trigeminal nerve a few mm proximal to the pons. www.indiandentalacademy.com 35
  • Causes of TN II. • SECONDARY/ SYMPTOMATIC forms: Tumor (Acoustic neurinoma, pontine glioma, epidermoid chondroma, metastases, lymphoma) Amyloidoma of Meckel’s Cave: A Rare Cause of Trigeminal Neuralgia, Eugene Yu ,University of Toronto Canada, AJR:182, June 2004 • Vascular (pontine infarcts, Aneurysms of Arteries, Veins, AV malform) Vertebrobasilar ectasia rare cause of TN (MRI of vertebrobasilar ectasia in TN, Kirsch et al, April 2005) • • Inflammatory (MS, sarcoidosis) Paraneoplastic {Marc E. et al, trig neuralgia, march 2006} www.indiandentalacademy.com 36
  • Vascular loops • The main cause of trigeminal neuralgia is neurovascular compression (NVC) in the root entry zone (REZ) of the trigeminal nerve in the CPA cistern {Norio Yoshino, et al, Radiology 2003} • Sup Cereb A > Ant inf Cerebellar A > smaller pontine arteries > petrosal veins {Lawrence et al, 1990} • Superior cerebellar artery (SCA)> the ant infer cerebellar A. (AICA)> the basilar artery, or the vertebral antery. {Robert et al, TN: MRI Features, Radiology:1989;172:767-70} www.indiandentalacademy.com 37
  • BASILAR ARTERY www.indiandentalacademy.com 38
  • Axial T2W MRI SCA (arrow) Compressing PGS of V (open arrow) www.indiandentalacademy.com 39
  • Images of a 64-year-old man with left-sided V2 and V3 distribution of facial pain. a. Coronal T1W MR: Focal area of signal void (white arrow) deforming the left fifth nerve (black arrow) at REZ. www.indiandentalacademy.com 40 b. AP Angiogram: Ectatic distal vertebral artery.
  • Vascular loops • Magnetic resonance angiography has been reported to be effective in the detection of NVC in trigeminal neuralgia • Norio Y. et al, Radiology 2003; Three-dimensional MR imaging with constructive interference in steady-state (3D – CISS) sequence images provided more sufficient information than did MR angiography • Nerve & Arteries- identified by both (MRA & 3D CISS) • But Veins- on 3D CISS images www.indiandentalacademy.com 41
  • • • • • • MR angiography, Artery - fast blood flow - high signal intensity & Nerve - intermediate signal intensity, Contrast between the artery & nerve good Contrast resolution betn CSF & nerve is somewhat unclear Depiction of the vein is impossible –cause of slow blood flow. www.indiandentalacademy.com 42
  • ` 3D CISS images – • Provide high spatial resolution & excellent contrast resolution betn CSF & nerve • Clearly depict the veins • 3D CISS imaging offers high spatial resolution & excellent contrast resolution & depicts both artery & vein responsible for the NVC. www.indiandentalacademy.com 43
  • 3D CISS MR images • Superior cerebellar artery (short arrow) has compressed the REZ of the right trigeminal nerve (long arrow) at the medial site. www.indiandentalacademy.com 44
  • MR angiographic images • Superior cerebellar artery (short arrow) has compressed the right trigeminal nerve (long arrow) at the medial site. www.indiandentalacademy.com 45
  • • (a) Transverse 3D CISS MR image: both vein (curved arrow) & ant inf cerebellar artery (short straight arrow) have compressed left trigeminal nerve (long straight arrow) at the REZ. • (b) Transverse MR angiographic image does not depict the vein, although it shows the ant inf cerebellar artery (short arrow)- has compressed the REZ of the left trigeminal nerve (long arrow). www.indiandentalacademy.com 46
  • Cisternal portion of V compressed by: 1. Extra axial diseases: • • • • • • Schwannomas Meningiomas Epidermoids Lipoma Metastasis Inflam parocesses 1. Intra axial diseases: • • • • MS Infarct Metastasis Primary tumors www.indiandentalacademy.com 47
  • Basilar Artery Aneurysm. Postcontrast axial CT. Angiographic confirmation Tubular-shaped area of enhancement in left cerebellopontine angle (arrows) typical for fusiform basilar artery aneurysm. Left-to-right shift of fourth ventricle. www.indiandentalacademy.com David et al, AJR 135:93- 95 1980 48
  • Multiple sclerosis • Prevalance: 1-8% in TN • Common cause of symptomatic TN, • Probably resulting from a demyelination plaque at the level of REZ • Frequently goes undiagnosed in patients who have relatively mild or infrequent MS exacerbations. • Should be considered in any person with TN symptoms, in younger TN patients or with bilateral TN. • A TN evaluation can be the first opportunity for the clinician to diagnose MS. www.indiandentalacademy.com 49
  • Multiple sclerosis • • • • • Neurologic symptoms seen in MS: Unexplained episodes of monocular blindness, Diplopia, Vertigo, Unusual clumsiness (ataxia), Weakness. • Routine brain CT scan - adequate to screen CPA tumor, • MRI scan - better demonstrates MS plaques & anatomic relationships of trigeminal root. www.indiandentalacademy.com 50
  • Multiple sclerosis • Axial T2W MRI • Plaques along intrapontine segments of both trig nerves Transient enhancement – resolution of enhancement occurs in 2 months in www.indiandentalacademy.com 51 contrast to neoplastic disease {Radiographics, Charles et al 1995}
  • Acoustic Schwannoma • • • • • • • Approx. 10 % of all intracranial tumors 80% -90% of all CPA tumors < 21 yrs Becomes symptomatic before 25 yrs Mostly arises within IAC If widening is >2mm – consider presence of tumour Clinical findings: – Tinnitus, – Hearing loss – Signs of cerebellar dysfunction www.indiandentalacademy.com 52
  • Acoustic Schwannoma T1W MRI Mass within the right www.indiandentalacademy.com into the CPA cistern 53 IAC with extension
  • Trigeminal schwannoma • 0.2% of all intracranial tumors • Majority – develop in gasserian ganglion • Clinical findings: – Sensory disturbance of T Nerve: – Numbness – Diminished/ absent corneal reflex – Hypesthesia – Hypalgesia – Weakness of muscles of mastication www.indiandentalacademy.com 54
  • Trigeminal schwannoma • The pressure exerted by the tumor leads to erosion of the underlying bone & enlargement of the foramen ovale, foramen rotundum, or the superior orbital fissure. • Small tumors are homogeneous; • Large tumors can have heterogeneous signal intensity due to degenerative changes, including cyst formation and fatty degeneration www.indiandentalacademy.com 55
  • Trigeminal schwannoma CE TI W Smoothly marginated tumors, Large, dumbbell- shaped enhancing tumor (arrows) in the left middle cranial fossa that follows the course of the trigeminal nerve and extends into the www.indiandentalacademy.com 56 pterygopalatine and posterior fossae.
  • Trigeminal schwannoma Most common Location: Gasserian ganglion T2W MRI T1W MRI High heterogeous signal intesity Smooth margins, low signal intesity www.indiandentalacademy.com 57
  • Trigeminal schwannoma www.indiandentalacademy.com 58
  • Meningioma • • • • 2nd most freq tumors occuring in CPA, 10- 15 % of all tumors Distinct female prediliction (2:1 to 4:1) Middle age www.indiandentalacademy.com 59
  • Meningioma • Signal intensity similar to acoustic schwannomas • Charac feature: Broad based attachment to adj dura matter www.indiandentalacademy.com 60
  • Epidermoid Cyst • • • • Rare - 0.2% to 1% of all intracranial tumors Most common location: CPA 5 – 9% of all CPA masses. 4th – 5th decade of life www.indiandentalacademy.com 61
  • Epidermoid Cyst • HP: composed of int layer of squam epith. covered by an ext fibrous capsule • These cysts grow by desquamation of epithelial cells that break down into keratin and cholesterol within the tumor capsule. • Grows slowly & is soft & very pliable www.indiandentalacademy.com 62
  • Epidermoid Cyst www.indiandentalacademy.com 63
  • Epidermoid Cyst www.indiandentalacademy.com 64
  • Trigeminal Epidermoid LOBULATED margins Axial T2W Axial T1W Moderately high heterogeneous signal intensity TE of Trig N & Meckel’s cave www.indiandentalacademy.com 65 Low signal intensity
  • Pontine Glioma • • • • 95% of neoplasms in brainstem are Astrocytomas In children betwn 5- 14 yrs M>F May be totally solid, – Solid with cystic, necrotic or hemorrhagic component • T1W: Isointense or hypointense If cystic: Hypointense • T2W: Hyperintense in both solid & cystic component • After Gd adminstration: solid comp - enhancement www.indiandentalacademy.com 66
  • Astrocytomas www.indiandentalacademy.com 67
  • Astrocytomas www.indiandentalacademy.com 68
  • Pontine Infarct • Pontine ischemia- due to bilateral ventral pontine infarction • Burning orofacial pain- early symptom • ‘Locked in Syndrome’- pt. is able to understand what is being said & happening, is imprisoned by inability to speak or move anything apart from eyes • Small infarcts – invisible in CT – Evident in MRI www.indiandentalacademy.com 69
  • Metastasis • Met. lesions involving CPA: 0.2% - 2% • Note obliteration of CSF in right Meckels cave by mass (large arrow) • Note expansion of convex dural margin by mass • Note normal cisternal portions of V bilaterally (small arrow) T2W MRI • Neoplastic lesions most commonly involve the extracranial branches • Spread by PNS www.indiandentalacademy.com 70
  • Conclusion • Diagnostic brain imaging should be part of the initial screening of all patient with TN symptoms - cause a significant % of patients have symptomatic TN • If TN identifiable cause, such as a tumor or mass compressing the nerve, the neurologist - elimination of the pathology or decompression of the nerve. • In cases of idiopathic TN, clinicians consider medical and surgical options. www.indiandentalacademy.com 71
  • • • • • MRI – useful in identification of MS or masses Gross Vascular changes: eg. Basilar A. dolichoectasia Magnetic resonance angiography- effective in NVC 3D CISS MR Imaging offers high spatial resolution & excellent contrast resolution & depicts both artery & vein responsible for the NVC. • Coronal MRI: PGS • Sagittal & Axial – detection of intraparenchymal lesions (MS) • AV malformation – Angiography {Lawrence et al, TN: MRI Assessment, Radiology1990} www.indiandentalacademy.com 72
  • Treatment • Medical – – – – – Carbamazepine + Baclofen / Clonezepam Phenytoin Gabapentin Valproate • Surgical – – – – – – – MV Decompression Peripheral injections Peripheral neurectomy Cryotherapy (Nitrous oxide cryo probe is used) Thermocoagulation (65°) Gasserian ganglion procedures Intracranial procedures www.indiandentalacademy.com 73
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  • 2. Pre-Trigeminal Neuralgia • • • Days to years before the first attack of TN pain, some sufferers experience odd sensations in the trigeminal distributions destined to become affected by TN. These odd sensations of pain, (such as a toothache) or discomfort (like "pins and needles", parasthesia), may be symptoms of pre-trigeminal neuralgia. Pre-TN is most effectively treated with medical therapy used for typical TN www.indiandentalacademy.com 75
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  • • Trigger zones may result from ephaptic coupling between partially damaged trigeminal axons that allows abnormal spread of excitation, facilitating a synchronous discharge of hyperexcitable trigeminal afferents that produce a pain attack. www.indiandentalacademy.com 79
  • • Pulsation of vessels do not visibly damage the nerve. • Irritation from repeated pulsations may lead to changes of nerve function, & deliver abnormal signals to the trigeminal nerve nucleus. • Causes hyperactivity of the trigeminal nerve nucleus, resulting in the generation www.indiandentalacademy.com 80 of TN pain
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  • • TN ‘‘trigger zone’’ is an area of facial skin or oral mucosa where low-intensity mechanical stimulation (such as light touch, an air puff, or even hair-bending) can elicit a typical pain attack. www.indiandentalacademy.com 82
  • Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com 83