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Chiari Malformation in otology practice
Auris Nasus Larynx 37 (2010) 95–99 www.elsevier.com/locate/anl
Chiari Malformation in otology practice Hilla Levo a,*, Erna Tapani b, Atte Karppinen c, Erna Kentala a a
Department of Otorhinolaryngology, Helsinki University Central Hospital, Helsinki, Finland b Department of Radiology, Helsinki University Central Hospital, Helsinki, Finland c Department of Neurosurgery, Helsinki University Central Hospital, Helsinki, Finland Received 20 August 2008; accepted 7 February 2009 Available online 5 May 2009
Abstract The purpose of the study was to evaluate prevalence, characteristic symptoms, and management of Chiari Malformation 1 (CM1). A retrospective chat review was made in Otology Tertiary Department including 439 otologic patients referred to the Helsinki University Hospital Radiology Department for head magnetic resonance imaging (MRI) during 2005 and also among 42 patients seen at the Department of Neurosurgery in years 2001–2005 with a diagnosis of CM1. We made a structured analysis of medical records focusing on patient history, neurologic symptoms, and radiologic findings. For surgical patients, information was collected on symptoms, treatment, and operative outcome. The prevalence of CM1 in the 439 otologic patients was 0.9%. Most CM1 patients sent to the Neurosurgery Department were operated on. Two months postoperatively, 26 patients (68%) had benefited from the surgery, but 12 patients (32%) experienced no change to symptoms. The possibility of CM1 should be borne in mind in patients presenting with atypical benign positional vertigo or recurrent facial paresis. # 2009 Elsevier Ireland Ltd. All rights reserved. Keywords: Vertigo; Otology
1. Introduction Chiari Malformation (CM) described 1891 by Hans von Chiari [1], is a congenital malformation of the hindbrain. CM is divided into different types according to the degree of prolapsed cerebellar amygdalae through the foramen magnum [2]. Chiari Malformation Type 1 (CM1), also known as adult-type Chiari Malformation, is the least severe form and also the predominant one [3]. CM1 has variable clinical presentation and onset [3]. The symptoms vary [4], neck pain or cough headache (headache worsened by cough) are common, but audiovestibular symptoms are rarely the sole primary symptoms [5]. Numerous different symptoms make the diagnosing difficult. On the other hand many are symptom less. The natural course of CM1 is unknown. The prognosis and long* Corresponding author at: Department of Otorhinolaryngology, Helsinki University Central Hospital, P.O. Box 220 (Haartmaninkatu 4 E), 00029 HUS, Finland. Tel.: +358 50 427 1492; fax: +358 9 471 75010. E-mail address: [email protected] (H. Levo).
term response to surgery is also variable [3]: some authors even question the benefit of surgery [3]. Vertigo and headache are common complaints among otologic patients. In autumn 2004 we found two patients in otoneurologic clinic who had CM1. The aim of this study was to evaluate the prevalence of CM1 in otologic patients and their characteristic symptoms as well as the benefit of the surgical care.
2. Materials and methods After finding two patients with CM1 we conducted a retrospective chart review of the otologic patients referred to the Helsinki University Hospital Radiology Department for head magnetic resonance imaging (MRI) during 2005. All images were reviewed and a neuroradiologist (ET) was consulted. Although the sagittal imaging of the craniocervical junction was not routinely included in the scan, the craniocervical junction could be evaluated. A diagnosis of CM1 was given when the cerebellar tonsils were located at
0385-8146/$ – see front matter # 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.anl.2009.02.004
96
H. Levo et al. / Auris Nasus Larynx 37 (2010) 95–99
Table 1 The indications for MRI in otology practice year 2005. Patients may experience more than one symptom at a time. Indication
% of patients
Hearing loss Tinnitus Vertigo Acoustic neuroma control Facial pain Osteoma, Sarcoidosis, Cholesteatoma, Anosmia Facial paresis Meningeoma control Head trauma Diplopia Mastoidal problems Breathing difficulties Meningitis
72 29 29 6 4 4 3 2 1 1 1 1 1
least 5 mm below the foramen magnum. We looked through the medical records of all the patients who underwent imaging, focusing on symptoms and clinical findings linked to the radiological findings. Finally, we did a retrospective chart review of CM patients seen at the Department of Neurosurgery over a 5year period (2001–2005); we analyzed their medical records and reviewed radiological findings, symptoms, treatment, and operative outcome.
3. Results 3.1. Radiological data A large number of otologic patients today are submitted to MRI of the head and posterior fossa for a variety of symptoms. In 2005, a total of 439 otologic patients underwent MRIs of the head/posterior fossa due to symptoms presented in Table 1. Mean age of these patients was 54 (range 1–90) years. All images were reviewed to identify possible CM, and a neuroradiologist (ET) was consulted. For six patients, the MRI series did not allow cerebellar tonsillar ectopy to be evaluated. The prevalence of CM1 in otology practice was 0.9%. Minor tonsillar ectopy failing to fulfill the criteria of CM1 was excluded. The symptoms and findings of the four patients who had CM1 in MRI are presented in Table 2.
Table 3 Symptoms and findings of CM1 patients visiting the Neurosurgery Department 2001–2005. Patients could have more than one symptom simultaneously. Symptoms
% of patients
Headache with exertions Numbness of limbs Vertigo Syringomyelia Hydrocephalus Chest pain Fainting Nystagmus Memory difficulties Sleep apnea Breathing difficulties Dysphagia Ataxia
86 50 38 36 12 10 7 7 7 5 5 5 2
3.2. Data from the Neurosurgery Department During 2001–2005 a total of 42 patients with a diagnosis of CM1 were referred to the Neurosurgery Department for possible surgery. The patients were found from the database by using the International Classification of Diseases (ICD10) diagnosis of Chiari Malformation Q07.7. The prevalence of CM1 seen at the Neurosurgery Department of our University district, with a population of about 2 million people, is 0.42/100,000 patients a year, but probably not all CM1 patients are referred for consultation. Of these 42 CM1 patients, 12 were male and 30 female. The mean age of male patients was 19 (range 3–40) and female 39 (range 6–77) years. The mean symptoms and preoperative findings are listed in Table 3. The symptoms had lasted for 0.2–30 (mean 4.9) years. Cerebellar tonsillar herniation varied from 5 to 30 (mean 13.1) mm. Syringomyelia was found in 15 patients preoperatively and hydrocephalus in 5. All but three patients were operated on. Suboccipital craniectomy and C1 laminectomy were performed as is typical in posterior fossa decompression [3]. The postoperative improvement was slow, and headache usually resolved during the first two months. Two months postoperatively, 26 patients (68%) had benefited from the surgery, 12 patients (31%) had no change in symptoms, and one patient (1%) was lost due to fatal dislodgement of the
Table 2 Findings of the four CM1 patients found from the radiological data. Patient
Age (years)
Sex
Other diseases
Symptoms
Headache
Tonsillar ectopy (mm)
1 2
24 30
Female Female
No No
Unknown Unknown
7 8
3 4
64 35
Female Male
RAa, ca mammae Congenital hip luxation, asthma
Recurrent facial paresis Recurrent facial paresis, numbness around mouth, loss of taste Sudden deafness, vertigo Meniere’s disease-like symptoms
Yes Neck pain
7 6
a
RA, rheumatoid arthritis.
H. Levo et al. / Auris Nasus Larynx 37 (2010) 95–99
traceostomy cannula. Difference appeared to be present in postoperative results of patients with syringomyelia and other CM1 patients. Only 43% of patients with syringomyelia improved after the surgery, whereas 80% of CM1 patients operated on because of headache or other neurologic symptoms felt better postoperatively. The three patients who were not operated on had stable symptoms. Conservative management was the patient’s preference in two cases, and one patient was not offered surgery due to a very high anesthesia risk. No follow-up data were available.
97
examinations no deviant otoneurologic findings could be seen. Eye movements were studied with 3D VOG, and only a few beats of nystagmus could be provoked by lateral extension of the neck, although the patient experienced strong vertigo, which lasted for several minutes. An MRI revealed CM1 (Fig. 1); the cerebellar tonsils clearly extended below the foramen magnum. The patient was referred to the Neurosurgery Department, but symptoms eased while waiting for the operation, and he is currently being followed up conservatively.
3.3. Cases from the Otology Tertiary Department 4. Discussion The first patient was a 70-year-old woman with normal hearing and right sided tinnitus persisting for 15 years. She had complained of light vertigo and unsteadiness for years, and had been treated as a benign positional vertigo patient for six months without success, and therefore was referred to our Clinic. She also suffered from occipital headaches. In clinical examinations, hearing and electronystagmography with caloric stimuli were symmetric. On otoneurologic examination, her walking was ataxic and the tong deviated to the right. Right/left positioning test provoked right-beating nystagmus. Video-oculography (VOG) showed atypical nystagmus, which changed direction. MRI revealed CM1; the cerebellar tonsils extended to the level of the lower margin of the atlas. The patient was referred to the Neurosurgery Department, where she was operated on. Recovery was good and headaches and vertigo diminished. The second patient was 16-year-old student who had migraines with aura since the age of 12 years. Since the age of 15, he got short-lasting vertigo attacks accompanied by unsteadiness and was referred to our Clinic. In clinical
Fig. 1. The 16-year-old student with Chiari malformation.
CM1 is increasingly being recognized on MRI of asymptomatic subjects [6] and some patients with a wide variety of clinical symptoms. The likelihood of tonsillar ectopia occurring as a random event is 0.004% [7]. Elster and Chen [8] estimated the incidence of symptomatic CM1 to be 0.5%. They also extrapolated from the study conducted by Barkovich et al. [9] that the incidence of tonsillar ectopia in the general population is around 3.5% [8]. We found four patients with CM1, two of whom had complained of mild headache. Symptoms of CM1 usually manifest during early adulthood [6], although the age of onset can vary. The prevalence of CM1 in our otologic population of 439 patients was 0.9%. We did not include tonsillar ectopia in our study. Wu et al. [10] found 76 children with CM1 among 8262 (0.9%) head MRIs. Elster and Chen [8] identified 68 CM1 cases in a study of 12,226 head MRIs (0.6%). Meadows et al. [6] reported a radiographic diagnosis of CM1 for 0.77% of 22,000 unselected MRIs, but only 14% of these cases were asymptomatic. We had a female/male ratio of CM1 patients of 2.5:1 among our neurosurgical cases and 3:1 among our radiologic cases. The female/male ratio varies, but Elster and Chen [8] suggest that 40% more cases occur in female patients. Milhorat [4] found the symptomatic female/male ratio to be 3:1 (275/89). In another study [6], only a slight female predominance of symptomatic CM1 patients was observed. Whether this predominance manifests primarily as initial cerebellar ectopia or during subsequent progression of the disorder is unknown [6]. As tonsillar ectopy is seen in MRI from time to time, a radiological diagnosis is mandatory [11]. The criterion for radiological diagnosis of CM1 is extension of the cerebellar tonsils at least 3–5 mm below the foramen magnum [11]. In adults, radiological criteria for extent of tonsillar herniation are not absolute, and should be considered within the clinicopathological context [1]. We used the criterion of cerebellar tonsils extending at least 5 mm below the foramen magnum, which is also used in our Neurosurgery Department. There were altogether 10 children or adolescents within the age of 1–18 years and none of them had tonsillar ectopy. The cerebellar tonsils rise with age, and tonsil herniation below 5 mm in the 2nd and 3rd decade, and below
98
H. Levo et al. / Auris Nasus Larynx 37 (2010) 95–99
4 mm in the 4th to 8th decade is suggested for the diagnosis of CM1 [12]. According to these criteria, all four patients identified here had CM1. None of these four patients were identified in the routine MRI examination. When MRI of the posterior fossa is performed to look for potential acoustic neuroma, the sagittal imaging of the craniocervical junction is not routinely included in the scan, and thus, the possible malformation is not imaged. To find CM, the radiologist must specifically be asked to look for it. Despite these problems, only in six cases were the MR scans done such that tonsillar ectopy could not be evaluated. The frequency of MR scans has increased, and thus, more CM1 could be seen as an incidental finding. One-sided hearing loss and/or tinnitus and/or vertigo were the most common reasons for posterior fossa MRI in our department. In CM1 there can be only one symptom or many [3]. Headache is the most common symptom [3], but unfortunately, the occurrence of headache was poorly documented in the medical records of our patients. Facial nerve paresis is not uncommon in CM1, and trigeminal symptoms are also seen [13]. The proximity of the cranial nerves as they exit the pontomedullary junction make them susceptible to the compressive effects of cerebellomedullary malformation such as CM1. Compression of cranial nerves and the brainstem is considered to be the mechanism underlying the trigeminal pain and other cranial nerve symptoms [14]. Dyste et al. [13] reported trigeminal symptoms in 26% of their CM1 patients and facial nerve symptoms in 6% (Table 4). Trigeminal symptoms were present in one and facial nerve symptoms in two of our four cases. Downbeat nystagmus is associated with CM as well as other types of nystagmus, too [15]. Both clinical cases had atypical nystagmus, neither downbeat nystagmus. Unfortunately nystagmus as a finding was poorly documented on the medical records of our patients. The prognosis and long-term response of CM1 to surgery is variable [3]. Headache and pain generally respond well to surgery [3], although at least 25% of patients have declining clinical course postoperatively. On the other hand, syringomyelia is a poor prognostic sign [3]. Syringomyelia is a progressive disorder and the signs and symptoms manifest as the syrinx expands [16]. Also in our series patients with syringomyelia had a poorer outcome postoperatively. Syringomyelia seems to be connected to a more Table 4 Cranial nerve (brainstem) symptoms in 50 CM1 patients (based on Dyste et al. [13]). Cranial nerve involved
%
Glossopharyngeus Vagus Trigeminus Hypoglossus Facial Abducens
30 30 26 18 6 2
difficult form of the malformation since the response to the surgery is poorer. Some of the patients had had symptoms for many years, one for 30 years, before operation. Those, who became worse after surgery belonged to that group of patients. Some patients become spontaneously symptom-free, as was the case with patient 2. Bindal et al. [17] created a classification of the symptoms to predict surgical outcome. They found that early diagnosis and treatment were best, with symptoms secondary to brain stem compression being reversible with decompression surgery, but the results with syringomyelia were not as promising. Dyste et al. [13] stated that early surgery to stabilize progression of the disease is better for symptomatic patients, a conclusion supported by our Neurosurgery Department. The decision to operate on is not simple. Headache seems to ease in the most of the cases, but we had no long-term results. In the mechanism behind the pain is a scar formation the headache probably comes back later on.
5. Conclusion The possibility of CM1 should be borne in mind in patients with atypical positional vertigo and recurrent facial paresis. Questions about headaches, especially related to head positioning and ‘‘cough headache’’, should be asked.
References [1] Bejjani GK. Definition of the adult Chiari malformation: a brief historical overview. Neurosurg Focus 2001;11(1):1–8. [2] Galvez MJN, Rodrigo JJF, Liesa RF, Gonza´lez EAV, Garrido CM, Sampe´riz LC, et al. Otorhinolaryngologic manifestations in Chiari Malformation. Am J Otol 2002;23(2):99–104. [3] Meadows J, Guarnieri M, Miller K, Haroun R, Kraut M, Carson BS. Type I Chiari malformation: a review of the literature. Neurosurg Q 2001;11(3):220–9. [4] Milhorat TH, Chou MW, Trinidad EM, Kula RW, Mandell M, Wolpert C, et al. Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients. Neurosurgery 1999;44(5): 1005–17. [5] Sperling NM, Franco RA, Milhorat TH. Otologic manifestations of Chiari I malformation. Otol Neurol 2001;22(5):678–81. [6] Meadows J, Kraut M, Guarnieri M, Haroun RI, Carson BS. Asymptomatic Chiari Type I malformations identified on magnetic resonance imaging. J Neurosurg 2000;92(6):920–6. [7] Cavender RK, Schmidt JH. Tonsillar ectopia and Chiari malformations: monozygotic triplets. Case report. J Neurosurg 1995;82(3): 497–500. [8] Elster AD, Chen MYM. Chiari I malformations: clinical and radiologic reappraisal. Radiology 1992;183(2):347–53. [9] Barkovich AJ, Millen KJ, Dobyns WB. A developmental classification of malformations of the brainstem. Ann Neurol 2007;62(6):625–39. [10] Wu YW, Chin CT, Chan KM, Barkovich AJ, Ferriero DM. Pediatric Chiari 1 malformations: do clinical and radiologic features correlate? Neurology 1999;53(6):1271–83. [11] Garland EM, Robertson D. Chiari I malformation as a cause of orthostatic intolerance symptoms: a media myth? Am J Med 2001;111(7): 546–52.
H. Levo et al. / Auris Nasus Larynx 37 (2010) 95–99 [12] Mikulis DJ, Diaz O, Egglin TK, Sanchez R. Variance of the position of the cerebellar tonsils with age: preliminary report. Radiology 1992; 183(3):725–8. [13] Dyste GN, Menezes AH, VanGilder JC. Symptomatic Chiari malformations. J Neurosurg 1989;71(2):159–68. [14] Kanpolat Y, Unlu A, Savas A, Tan F. Chiari Type I malformation presenting as glossopharyngeal neuralgia: case report. Neurosurgery 2000;48(1):226–8.
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[15] Kumar A, Patni A, Charbel F. The Chiari I malformation and the neurologist. Otol Neurotol 2002;23:727–35. [16] Bogdanov EI, Mendelevich EG. Syrinx size and duration of symptoms predict the pace of progressive myelopathy: retrospective analysis of 103 unoperated cases with craniocervical junction malformations and syringomyelia. Clin Neurol Neurosurg 2002;104(2):90–7. [17] Bindal AK, Dunsker SB, Tew JM. Chiari I malformation: classification and management. Neurosurgery 1995;37(6):1069–74.
Chiari Malformation in otology practice Hilla Levo a,*, Erna Tapani b, Atte Karppinen c, Erna Kentala a a
Department of Otorhinolaryngology, Helsinki University Central Hospital, Helsinki, Finland b Department of Radiology, Helsinki University Central Hospital, Helsinki, Finland c Department of Neurosurgery, Helsinki University Central Hospital, Helsinki, Finland Received 20 August 2008; accepted 7 February 2009 Available online 5 May 2009
Abstract The purpose of the study was to evaluate prevalence, characteristic symptoms, and management of Chiari Malformation 1 (CM1). A retrospective chat review was made in Otology Tertiary Department including 439 otologic patients referred to the Helsinki University Hospital Radiology Department for head magnetic resonance imaging (MRI) during 2005 and also among 42 patients seen at the Department of Neurosurgery in years 2001–2005 with a diagnosis of CM1. We made a structured analysis of medical records focusing on patient history, neurologic symptoms, and radiologic findings. For surgical patients, information was collected on symptoms, treatment, and operative outcome. The prevalence of CM1 in the 439 otologic patients was 0.9%. Most CM1 patients sent to the Neurosurgery Department were operated on. Two months postoperatively, 26 patients (68%) had benefited from the surgery, but 12 patients (32%) experienced no change to symptoms. The possibility of CM1 should be borne in mind in patients presenting with atypical benign positional vertigo or recurrent facial paresis. # 2009 Elsevier Ireland Ltd. All rights reserved. Keywords: Vertigo; Otology
1. Introduction Chiari Malformation (CM) described 1891 by Hans von Chiari [1], is a congenital malformation of the hindbrain. CM is divided into different types according to the degree of prolapsed cerebellar amygdalae through the foramen magnum [2]. Chiari Malformation Type 1 (CM1), also known as adult-type Chiari Malformation, is the least severe form and also the predominant one [3]. CM1 has variable clinical presentation and onset [3]. The symptoms vary [4], neck pain or cough headache (headache worsened by cough) are common, but audiovestibular symptoms are rarely the sole primary symptoms [5]. Numerous different symptoms make the diagnosing difficult. On the other hand many are symptom less. The natural course of CM1 is unknown. The prognosis and long* Corresponding author at: Department of Otorhinolaryngology, Helsinki University Central Hospital, P.O. Box 220 (Haartmaninkatu 4 E), 00029 HUS, Finland. Tel.: +358 50 427 1492; fax: +358 9 471 75010. E-mail address: [email protected] (H. Levo).
term response to surgery is also variable [3]: some authors even question the benefit of surgery [3]. Vertigo and headache are common complaints among otologic patients. In autumn 2004 we found two patients in otoneurologic clinic who had CM1. The aim of this study was to evaluate the prevalence of CM1 in otologic patients and their characteristic symptoms as well as the benefit of the surgical care.
2. Materials and methods After finding two patients with CM1 we conducted a retrospective chart review of the otologic patients referred to the Helsinki University Hospital Radiology Department for head magnetic resonance imaging (MRI) during 2005. All images were reviewed and a neuroradiologist (ET) was consulted. Although the sagittal imaging of the craniocervical junction was not routinely included in the scan, the craniocervical junction could be evaluated. A diagnosis of CM1 was given when the cerebellar tonsils were located at
0385-8146/$ – see front matter # 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.anl.2009.02.004
96
H. Levo et al. / Auris Nasus Larynx 37 (2010) 95–99
Table 1 The indications for MRI in otology practice year 2005. Patients may experience more than one symptom at a time. Indication
% of patients
Hearing loss Tinnitus Vertigo Acoustic neuroma control Facial pain Osteoma, Sarcoidosis, Cholesteatoma, Anosmia Facial paresis Meningeoma control Head trauma Diplopia Mastoidal problems Breathing difficulties Meningitis
72 29 29 6 4 4 3 2 1 1 1 1 1
least 5 mm below the foramen magnum. We looked through the medical records of all the patients who underwent imaging, focusing on symptoms and clinical findings linked to the radiological findings. Finally, we did a retrospective chart review of CM patients seen at the Department of Neurosurgery over a 5year period (2001–2005); we analyzed their medical records and reviewed radiological findings, symptoms, treatment, and operative outcome.
3. Results 3.1. Radiological data A large number of otologic patients today are submitted to MRI of the head and posterior fossa for a variety of symptoms. In 2005, a total of 439 otologic patients underwent MRIs of the head/posterior fossa due to symptoms presented in Table 1. Mean age of these patients was 54 (range 1–90) years. All images were reviewed to identify possible CM, and a neuroradiologist (ET) was consulted. For six patients, the MRI series did not allow cerebellar tonsillar ectopy to be evaluated. The prevalence of CM1 in otology practice was 0.9%. Minor tonsillar ectopy failing to fulfill the criteria of CM1 was excluded. The symptoms and findings of the four patients who had CM1 in MRI are presented in Table 2.
Table 3 Symptoms and findings of CM1 patients visiting the Neurosurgery Department 2001–2005. Patients could have more than one symptom simultaneously. Symptoms
% of patients
Headache with exertions Numbness of limbs Vertigo Syringomyelia Hydrocephalus Chest pain Fainting Nystagmus Memory difficulties Sleep apnea Breathing difficulties Dysphagia Ataxia
86 50 38 36 12 10 7 7 7 5 5 5 2
3.2. Data from the Neurosurgery Department During 2001–2005 a total of 42 patients with a diagnosis of CM1 were referred to the Neurosurgery Department for possible surgery. The patients were found from the database by using the International Classification of Diseases (ICD10) diagnosis of Chiari Malformation Q07.7. The prevalence of CM1 seen at the Neurosurgery Department of our University district, with a population of about 2 million people, is 0.42/100,000 patients a year, but probably not all CM1 patients are referred for consultation. Of these 42 CM1 patients, 12 were male and 30 female. The mean age of male patients was 19 (range 3–40) and female 39 (range 6–77) years. The mean symptoms and preoperative findings are listed in Table 3. The symptoms had lasted for 0.2–30 (mean 4.9) years. Cerebellar tonsillar herniation varied from 5 to 30 (mean 13.1) mm. Syringomyelia was found in 15 patients preoperatively and hydrocephalus in 5. All but three patients were operated on. Suboccipital craniectomy and C1 laminectomy were performed as is typical in posterior fossa decompression [3]. The postoperative improvement was slow, and headache usually resolved during the first two months. Two months postoperatively, 26 patients (68%) had benefited from the surgery, 12 patients (31%) had no change in symptoms, and one patient (1%) was lost due to fatal dislodgement of the
Table 2 Findings of the four CM1 patients found from the radiological data. Patient
Age (years)
Sex
Other diseases
Symptoms
Headache
Tonsillar ectopy (mm)
1 2
24 30
Female Female
No No
Unknown Unknown
7 8
3 4
64 35
Female Male
RAa, ca mammae Congenital hip luxation, asthma
Recurrent facial paresis Recurrent facial paresis, numbness around mouth, loss of taste Sudden deafness, vertigo Meniere’s disease-like symptoms
Yes Neck pain
7 6
a
RA, rheumatoid arthritis.
H. Levo et al. / Auris Nasus Larynx 37 (2010) 95–99
traceostomy cannula. Difference appeared to be present in postoperative results of patients with syringomyelia and other CM1 patients. Only 43% of patients with syringomyelia improved after the surgery, whereas 80% of CM1 patients operated on because of headache or other neurologic symptoms felt better postoperatively. The three patients who were not operated on had stable symptoms. Conservative management was the patient’s preference in two cases, and one patient was not offered surgery due to a very high anesthesia risk. No follow-up data were available.
97
examinations no deviant otoneurologic findings could be seen. Eye movements were studied with 3D VOG, and only a few beats of nystagmus could be provoked by lateral extension of the neck, although the patient experienced strong vertigo, which lasted for several minutes. An MRI revealed CM1 (Fig. 1); the cerebellar tonsils clearly extended below the foramen magnum. The patient was referred to the Neurosurgery Department, but symptoms eased while waiting for the operation, and he is currently being followed up conservatively.
3.3. Cases from the Otology Tertiary Department 4. Discussion The first patient was a 70-year-old woman with normal hearing and right sided tinnitus persisting for 15 years. She had complained of light vertigo and unsteadiness for years, and had been treated as a benign positional vertigo patient for six months without success, and therefore was referred to our Clinic. She also suffered from occipital headaches. In clinical examinations, hearing and electronystagmography with caloric stimuli were symmetric. On otoneurologic examination, her walking was ataxic and the tong deviated to the right. Right/left positioning test provoked right-beating nystagmus. Video-oculography (VOG) showed atypical nystagmus, which changed direction. MRI revealed CM1; the cerebellar tonsils extended to the level of the lower margin of the atlas. The patient was referred to the Neurosurgery Department, where she was operated on. Recovery was good and headaches and vertigo diminished. The second patient was 16-year-old student who had migraines with aura since the age of 12 years. Since the age of 15, he got short-lasting vertigo attacks accompanied by unsteadiness and was referred to our Clinic. In clinical
Fig. 1. The 16-year-old student with Chiari malformation.
CM1 is increasingly being recognized on MRI of asymptomatic subjects [6] and some patients with a wide variety of clinical symptoms. The likelihood of tonsillar ectopia occurring as a random event is 0.004% [7]. Elster and Chen [8] estimated the incidence of symptomatic CM1 to be 0.5%. They also extrapolated from the study conducted by Barkovich et al. [9] that the incidence of tonsillar ectopia in the general population is around 3.5% [8]. We found four patients with CM1, two of whom had complained of mild headache. Symptoms of CM1 usually manifest during early adulthood [6], although the age of onset can vary. The prevalence of CM1 in our otologic population of 439 patients was 0.9%. We did not include tonsillar ectopia in our study. Wu et al. [10] found 76 children with CM1 among 8262 (0.9%) head MRIs. Elster and Chen [8] identified 68 CM1 cases in a study of 12,226 head MRIs (0.6%). Meadows et al. [6] reported a radiographic diagnosis of CM1 for 0.77% of 22,000 unselected MRIs, but only 14% of these cases were asymptomatic. We had a female/male ratio of CM1 patients of 2.5:1 among our neurosurgical cases and 3:1 among our radiologic cases. The female/male ratio varies, but Elster and Chen [8] suggest that 40% more cases occur in female patients. Milhorat [4] found the symptomatic female/male ratio to be 3:1 (275/89). In another study [6], only a slight female predominance of symptomatic CM1 patients was observed. Whether this predominance manifests primarily as initial cerebellar ectopia or during subsequent progression of the disorder is unknown [6]. As tonsillar ectopy is seen in MRI from time to time, a radiological diagnosis is mandatory [11]. The criterion for radiological diagnosis of CM1 is extension of the cerebellar tonsils at least 3–5 mm below the foramen magnum [11]. In adults, radiological criteria for extent of tonsillar herniation are not absolute, and should be considered within the clinicopathological context [1]. We used the criterion of cerebellar tonsils extending at least 5 mm below the foramen magnum, which is also used in our Neurosurgery Department. There were altogether 10 children or adolescents within the age of 1–18 years and none of them had tonsillar ectopy. The cerebellar tonsils rise with age, and tonsil herniation below 5 mm in the 2nd and 3rd decade, and below
98
H. Levo et al. / Auris Nasus Larynx 37 (2010) 95–99
4 mm in the 4th to 8th decade is suggested for the diagnosis of CM1 [12]. According to these criteria, all four patients identified here had CM1. None of these four patients were identified in the routine MRI examination. When MRI of the posterior fossa is performed to look for potential acoustic neuroma, the sagittal imaging of the craniocervical junction is not routinely included in the scan, and thus, the possible malformation is not imaged. To find CM, the radiologist must specifically be asked to look for it. Despite these problems, only in six cases were the MR scans done such that tonsillar ectopy could not be evaluated. The frequency of MR scans has increased, and thus, more CM1 could be seen as an incidental finding. One-sided hearing loss and/or tinnitus and/or vertigo were the most common reasons for posterior fossa MRI in our department. In CM1 there can be only one symptom or many [3]. Headache is the most common symptom [3], but unfortunately, the occurrence of headache was poorly documented in the medical records of our patients. Facial nerve paresis is not uncommon in CM1, and trigeminal symptoms are also seen [13]. The proximity of the cranial nerves as they exit the pontomedullary junction make them susceptible to the compressive effects of cerebellomedullary malformation such as CM1. Compression of cranial nerves and the brainstem is considered to be the mechanism underlying the trigeminal pain and other cranial nerve symptoms [14]. Dyste et al. [13] reported trigeminal symptoms in 26% of their CM1 patients and facial nerve symptoms in 6% (Table 4). Trigeminal symptoms were present in one and facial nerve symptoms in two of our four cases. Downbeat nystagmus is associated with CM as well as other types of nystagmus, too [15]. Both clinical cases had atypical nystagmus, neither downbeat nystagmus. Unfortunately nystagmus as a finding was poorly documented on the medical records of our patients. The prognosis and long-term response of CM1 to surgery is variable [3]. Headache and pain generally respond well to surgery [3], although at least 25% of patients have declining clinical course postoperatively. On the other hand, syringomyelia is a poor prognostic sign [3]. Syringomyelia is a progressive disorder and the signs and symptoms manifest as the syrinx expands [16]. Also in our series patients with syringomyelia had a poorer outcome postoperatively. Syringomyelia seems to be connected to a more Table 4 Cranial nerve (brainstem) symptoms in 50 CM1 patients (based on Dyste et al. [13]). Cranial nerve involved
%
Glossopharyngeus Vagus Trigeminus Hypoglossus Facial Abducens
30 30 26 18 6 2
difficult form of the malformation since the response to the surgery is poorer. Some of the patients had had symptoms for many years, one for 30 years, before operation. Those, who became worse after surgery belonged to that group of patients. Some patients become spontaneously symptom-free, as was the case with patient 2. Bindal et al. [17] created a classification of the symptoms to predict surgical outcome. They found that early diagnosis and treatment were best, with symptoms secondary to brain stem compression being reversible with decompression surgery, but the results with syringomyelia were not as promising. Dyste et al. [13] stated that early surgery to stabilize progression of the disease is better for symptomatic patients, a conclusion supported by our Neurosurgery Department. The decision to operate on is not simple. Headache seems to ease in the most of the cases, but we had no long-term results. In the mechanism behind the pain is a scar formation the headache probably comes back later on.
5. Conclusion The possibility of CM1 should be borne in mind in patients with atypical positional vertigo and recurrent facial paresis. Questions about headaches, especially related to head positioning and ‘‘cough headache’’, should be asked.
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