Posterior Fossa Arachnoid Cysts as Findings in an Ataxia Clinic

Marie-Catherine Boll; Rolando Aburto Méndez; Emiliano Antonio Gómez Rodríguez; Alejandro Monroy Calderón; Dianela Gasca  Saldaña

Posterior Fossa Arachnoid Cysts as Findings in an Ataxia Clinic

Authors: Marie-Catherine Boll^1,2*, Rolando Aburto Méndez^1,2, Emiliano Antonio Gómez Rodríguez^1,2, Alejandro Monroy Calderón^1,2, Dianela Gasca Saldaña¹

^*Corresponding Author: Boll MC , Clinical research laboratory, division of neurology, rare movement disorders, Institutional National Neurology and Neurocirculation Manuel Velasco Suarez, Insurgentes Sur 3877, La Fama, Tlalpan, 14269. Mexico City, Mexico

¹Clinical research laboratory, division of neurology, rare movement disorders, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suarez, Mexico

²National Autonomous University of Mexico, Mexico

Received Date: 22 June 2022

Accepted Date: 25 June 2022

Published Date: 28 June 2022

Citation: Boll MC, Aburto Mendez R, Gómez Rodríguez EA, ,Monroy Calderón A, Gasca Saldaña D. (2022) Posterior Fossa Arachnoid Cysts as Findings in an Ataxia Clinic. Ann Case Report 7: 878. DOI: https://doi.org/10.29011/2574-7754.100878

Abstract

Arachnoid cysts are collections of cerebrospinal fluid surrounded by an arachnoid membrane. Most of them are asymptomatic and are detected incidentally on imaging studies. Others reveal themselves with a variety of clinical symptoms depending on their size and location. Although most located in the temporal fossa, cysts can be found in any compartment of the brain or spinal cord. Posterior fossa arachnoid cysts (PFAC) account for 5-48% of all arachnoid cysts. In this case series, we analyze relevant features of 27 PFAC reviewed in an ataxia and other rare diseases clinic.

Keywords: Arachnoid cysts, posterior cranial fossa, magnetic resonance imaging, ataxia, outcome assessment.

Introduction

The first description of arachnoid cysts was made by the English physician Richard Bright in 1827, under the name “serous cysts”. He described two cases, both discovered by autopsy, in his book “Reports of Medical Cases: Selected with a View of Illustrating the Symptoms and Cure of Diseases by a Reference to Morbid Anatomy”. Since then and due to the lack of consensus, these cysts have been variously named as “chronic cystic arachnoiditis”, “cisternal arachnoiditis”, “serous meningitis” among others [1]. Arachnoid cysts (AC) are malformations consisting of collections of cerebrospinal fluid surrounded by arachnoid membranes and located in the subarachnoid space. These malformations are benign, most often congenital, extra-axial and represent 1% of all intracranial lesions [2-4]. By location, they can be classified into two major groups: Supratentorial AC (46-90%) and Infratentorial AC (5- 48%) [5-9]. Supratentorial cysts are most commonly located in the middle fossa (32-60%), while posterior fossa arachnoid cysts (PFAC) are predominantly retro cerebellar (35-85%) [10,11]. AC can be classified as primary (congenital) and secondary [6,12]. The primary ones originate from the separation of arachnoid membranes during embryological development, due to a circumscribed increase in the pulsation of cerebrospinal fluid [7]. Secondary AC are not as common and can develop as a result of head injuries, hemorrhages or infections. Ultrastructural studies have classified them into 3 types: type 1, arachnoidlike morphology; type 2, fibrous morphology, which are thicker walls than normal arachnoids; type 3 of aberrant morphology, which can contain hair cells in its luminal part, and the presence of microvilli and glial cell processes. [13] An ectopic arachnoid plexus has also been found within arachnoid cysts [14]. Different classifications of posterior fossa cysts (PFAC) have been proposed (Table1). Also, different surgical techniques have been proposed in symptomatic cases (Table 2). Most cases are asymptomatic and are detected incidentally on imaging studies performed for another not associated causes [11,15]. The symptomatology depends on the location of the cysts [16,17]. Headache is the most prevalent clinical manifestation followed by increased intracranial pressure, seizures, hydrocephalus, ataxia or gait instability, hemiparesis, dyskinesias, altered mental status, blurred vision, and hearing loss [5,8,11,18]. In posterior fossa AC, imbalance and dizziness represent cardinal symptoms, in addition to presenting hearing loss or facial palsy [4]. The most relevant imaging study to analyze these cysts is volumetric magnetic resonance imaging, due to its better definition of the posterior fossa, although ultrasound is used in intrauterine screening. In the MRI study well defined lesions are observed, which displace adjacent structures, which do not contain lipidic or protein substances in their interior, and which have the same intensity as the cerebrospinal fluid, in all sequences. They may cause cranial deformities in some cases. AC can be confused with epidermal cysts, but the difference is usually found on diffusion-weighted imaging (DWI) where epidermal cysts appear hyperintense, due to their protein components, also hyperintense on FLAIR, as opposed to arachnoid cysts, which are hypointense on both sequences. Most arachnoid cysts are asymptomatic and have no changes over time, so conservative treatment in these cases is recommended [19]. Few cases have been reported in the literature that have varied in size or even disappeared in subsequent control studies [20-22]. Rare complications have also been reported, such as herniation of the cyst through the foramen magnum, sudden loss of visual acuity, intracystic hemorrhage [23-25], subdural hematomas [26], and intracranial hypertension. It is important to identify complications due to compression, which causes alteration first of the structures adjacent to the cyst, and then of distant structures [27]. Patients who have undergone surgery show improvement in language, motor symptoms and neuropsychological status [28,29]. The risk of recurrence varies according to series and procedures with an average of 30%. After excision of the cyst, and 30-50% after endoscopic procedure. Other post-surgical complications include spasticity, hemiparesis, headache, CSF leakage, hydrocephalus, subdural hygroma [Pradilla], hemorrhage, tonsillar and craniocervical herniation [30,31]. In the case of placing a shunt, it may malfunction or become infected [32] while relatively good results have been described using marsupialization or endoscopic cisternostomy in children with PFAC [33].

Materials and Methods

We present 20 patients with posterior fossa arachnoid cysts diagnosed in the ataxia clinic of a single neurological center, reviewed between 2014 and 2019. The study of this series focuses on the clinical characteristics, surgical indications, evolution of these patients and complementary examinations. For each patient, we collected data including family history, birth complications, head injuries, morbidities, age of onset, current age, surgeries, before performing a complete medical and neurological examination. We define ataxia as the loss of coordination of movements and loss of balance due to dysfunction of the cerebellum or its afferent and efferent pathways. We assessed the degree of ataxia with the SARA scale [42]. In addition, other neurological manifestations were recorded.

Patients

Of 123 patients with sporadic ataxia that we reviewed, 20 have posterior fossa arachnoid cysts evidenced by magnetic resonance imaging or computed tomography. Arachnoid cysts found in regions other than the posterior fossa, cystic lesions such as epidermoid cysts or other tumor lesions were excluded. It is worth mentioning that in all sporadic or recessive cases, the molecular diagnosis of Friedreich’s ataxia was performed. If possible and indicated, next-generation sequencing was requested. The morphological evaluation of the cysts was performed retrospectively through 3D magnetic resonance imaging with Carestream Vue Motion software, preferably using the FIESTA sequence. The anteroposterior and major transverse diameters were measured in axial images (d1 and d2) and the height in sagittal sections (H). While in 3 cases voxel-based volumetry was performed, in all cases the following formula was used [43]:

Tables

Reference	Classifications
Little JR, et al. 1973 [10]	Cerebellopontine Angle (CPA)	Midnline Inferior	Midline Superior	Hemispheric	Clivus	Tentorial Notch
Vaquero J, et al. 1981 [34]	Supracerebellar	Retrocerebellar	Laterocerebellar	Clival	Mixed Cysts
		Type A	Type B
Arai & Sato 1990 [35]	Retrocerebellar (Type A & B)	(Without maldeveloped rhombencephalic roof)	(With maldeveloped rhombencephalic roof)	Hemispheric	CPA
Al-Holou, 2013 [8]	Retrocerebellar	Supracerebellar	Laterocerebellar	CPA	Quadrigeminal Cistern	Ambient Cistern	Brainstem
		Group 2	Group 3	Group 4
de Carvalho, 2014 [7]	Group 1 AC of the CPA	AC of the CPA with extension in dorsal surface of the brainstem	AC located inside the internal auditory canal	AC located in the dorsal part of the cerebellum

Table 1: Classifications of arachnoid cysts of the posterior fossa.

Authors	Year	Number of cases	Average age	Surgical technique	Results
Pradilla et al. [2]	2007	20	10.9 y	Endoscopic 73%, Open 27%: Craniotomy 5%, Fenestration 11%, Laminectomy 5%	Improvement in symptoms and stable cysts 60%, Complete resolution of symptoms 13%, ongoing symptoms 13%
Tunes et al. [4]	2015	4	42 y	Fenestration by craniotomy (4)	Asymptomatic 3, improvement 1
Al Holou et al. [8]	2013	661	> 19 y	Surgical 24 of 35 symptomatic	Increase in size: 5, reduction in size: 2, worsening of symptoms: 2
Helland et al. [9]	2007	156	39 y	Craniotomy and cystocisternal fenestration 122, shunt 34	Temporal: asymptomatic 50%, improvement 30.6%, equal 12%, worst 7.4%. Frontal: asymptomatic 54.5%, improvement 40.9% worst 4.6%. Posterior fossa:, asymptomatic 5, improvement 5, unchanged 2, worsening in 1
Boutarbouch et al. [5]	2008	32	32 y	Cleavage and marsupialization (17), stereotactic aspiration (4), Endoscopic fenestration (2), cystoperitoneal shunt 3 (2 due to recurrence). Conservative treatment (8)	Improvement 23, unchanged 6, worsening 1. Recurrence: 7.
Ciricillo et al. [15]	1991	40	4.3 y	Craniotomy and fenestration to the space SA (15), Shunt Cystoperitoneal (14), Shunt ventriculoperitoneal (6). Tx conservative (5).	Size reduction 34 of 35. Obliteration:10. Complication by fenestration: 6 of 15. Shunt revision : 9 of 28
Gui et al. [36]	2015	28	5 m- 42 y	Ventricle Endoscopic cystostomy 10, ventriculostomy of the third endoscopic ventricle 28	Total success (symptoms, size, hydrocephalus) in 25, endoscopic reintervention 1, posterior bypass placement 2. Reduction in size 22. Subdural collection 4
Karabatsou et al. [37]	2007	39	15.8 y	Endoscopic: Cystocisternotomy 27, cysto ventriculostomy 22, ventriculostomy of third ventricle 9	Improvement 35, symptoms 3, unchanged 1, slight improvement 1
Kim et al. [38]	1999	7	2- 62 y	Cystocisternotomy 4, cistoventriculostomy 1, ventriculocystostomy 1, ventriculocistocisternotomy 1	Intracisternal bleeding 1, Relief of symptoms 7, reduction of cyst 7
Raffael et al. [39]	1988	31	4.4 y	Craniotomy and Fenestration 29, cystoperitoneal shunt 5	Successful procedures 22 (76%), Subsequent placement of cystoperitoneal shunt 7. Reduction in size 30. 2 of 4 no longer require antiepileptic drugs
Zhang et al. [19]	2012	62	1-13 y	Cystoperitoneal shunt 62	Size reduction 59
Hayashi et al. [40]	1979	12	3 m-19 y	Frontotemporal craniotomy and fenestration 8, shunt VA 1, suboccipital craniotomy 1, cystoperitoneal shunt 1	No intervention 2, Improvement 9, No change 1
Yamakawa et al. [41]	1991	39	30-90 y	Resection 15, shunt 4. Conservative in the others	• Improvement in16 of 21 surgeries
Khan et al. [2]	2013	45	2m- 71 y	Fenestration by craniotomy, shunt, endoscopic fenestration and guided craniotomy	Cysts smaller than 2.50 cm have a better improvement than those who had a cyst larger than 5 cm.
Srinivasan US et al. [11]	2015	26	21-54 y	7 treated surgically	AC can be safely excised with an excellent long-term result except for the ventricular and retroclivial cysts. Midline AC require cystoperitoneal shunting or endoscopic fenestration due to risk of recurrence

Table 2: Surgical approaches to fossa posterior arachnoid cysts and outcome.

Current age, yrs/sex	Age at onset	Background	Location	Vol. (ml)	First symptom	Cephalalgia	Ataxia (SARA)	MoCA	ICH	Pyramidal syndrome	Outcome
25/F	20	Down Syndrome	RV & RH	6.3	Pseudopapiloedema	no	+		No	No	Stability
31/M	1	Frontotemporal epilepsy	RV & RH	16.5	Seizures	no	Loss of balance, falls, mood changes	29	No	No	Stability
23/M	2	Febrile seizures	RV & RH	23.5	Cephalic and hands tremor/ Nystagmus	+++	+++ (14)	30	+++	Yes	Partial improvement
40/M	6	3 Traumatic head injuries	RV, H & CC	52.27	VA decrease	ocular	+++ (14.5)	30	No	No	Blindness
46/M	8	Slight psychomotor retardation	RV & H	43.18	Dysarthria	++	+++ (14)	27	No	No	Partial improvement
38/M	8	Right palpebral ptosis	RV-RH (L)	3.85	Right palpebral Ptosis	-	++ (10)	23	No	Yes	Negative FRDA and NPC
42/M	8	Brother with similar condition	RV & H	94	Ataxic gait	-	+		No	Yes	Intermittent headache- ARSACS
39/M	9	Brother with similar condition	RV	47.9	Ataxic gait	+	+++ (18)	15	No	Yes	Gait worsening- ARSACS
40/M	14	-	RV, RH (L) & CC	5.8	Ataxic gait/ pes cavus	-	+++ (11)		No	Yes	FRDA excluded
39/F	7	Seizures/ Traumatic head injury	RV, IV, CC, CM	41	Ataxic gait	-	+(28.5)	10	No	Yes	Unverricht- Lundborg disease diagnosed cyst fenestration programmed
32/M	17	Traumatic head injury	RV & CM	3	Scanning speech	+++	++	20	No	Yes	Surgery programmed
30/M	18	-	CM	3	Low amplitude rest tremor	++	++		No	Yes	Under study
25/M	18	Ataxia with spastic paraparesis	RV & RH(L)	27	Toe walking	++	+ spastic gait (8)	24	No	Yes	FRDA excluded
31/M	21	Schwannoma radiosurgery	RV (2 cysts)	3.9	Peripheral facial nerve palsy	-	-		No	No	Stability
32/F	21	-	RV (2 cysts)	3	Ataxic gait	-	+ (20.5)	12	No	Yes	Stability under treatment for SANDO
28/M	23	-	CM	3.24	Falls	-	++	.	No	Yes	Under physical and cognitive therapy
54/M	34	Nasal septum fracture/obstructive sleep apnea	CM	3	Diplopia	+	+	.	No	No	Spontaneous cyst regressing
57/M	50	-	RV & RH	18.34	Ataxic gait	+	+ (19)	25	No	Yes	-
64/M	57	Alcoholism	IV & CM	27	Dizziness, headache, scanning speech	+	+	25	Yes	-	Total improvement with cysto cisternal derivation
61/M	58	-	RV & IH	4.45	Falls		+	.	No	Yes	Dies by fall
25/F	22	-	Supratentorial, infratentorial & spinal	string of cysts	Headache	+++	-	25	No	No	Only tensional symptoms
14/F	8	Secondary hydrocephalus	CC	3	Intracranial hypertension	++	-	-	Yes	-	Asymptomatic after VP shunt + cystoventricular shunt
42/F	37	Treated for Multiple Sclerosis	CC	3.39	Loss of balance, falls, mood changes	++	+(4)	28	No	No	Asymptomatic
16/M	13	Dominantly-Inherited Spinocerebellar Ataxia	CM& RH (R)	7	Ataxic gait	no	+	27	No	No	SCA2
47/F	33	Dominantly-Inherited Spinocerebellar Ataxia	CM	7	Slow saccades/ muscle cramps	no	+++	MMSE 28	No	No	SCA2
53/F	31	Familial epilepsy	RV	7.5	Myoclonus, ptosis, weakness	+	+	-	-	-	Spontaneous improvement
17/M	12	Huntington Disease	RV	6.02	trunk and extremities dystonia	-	+	No	No	No	disease progression

RV: Retrovermian Cyst; RH: Retrohemispheric Cyst; CC: Quadrigeminal Cistern Cyst (Quadrigeminal Plate Region); IV: Intraventricular Cyst; CM: Cisterna Magna Cyst; R: Right; L: Left; SARA: Scale For The Assessment And Rating Of Ataxia; Moca: Montreal Cognitive Assessment; ICH: Intracranial Hypertension; FRDA: Friedreich Ataxia; NPC: Nieman Pick Type C; SCA2: Spinocerebellar Ataxia Type 2; SANDO: Sensory Ataxic Neuropathy, Dysarthria, Ophthalmoparesis: ARSACS: Autosomal Recessive Spastic Ataxia Of Charlevoix-Saguenay.

Table 3: Clinical characteristics of the series of patients.