full article Prevalence of Sacral Spinal (Tarlov) Cysts in Persistent Genital Arousal Disorder

Prevalence of Sacral Spinal (Tarlov) Cysts in Persistent Genital
Arousal Disorderjsm_2765 1..10
Barry R. Komisaruk, PhD*† and Huey-Jen Lee, MD†
*Department of Psychology, Rutgers, The State University of New Jersey, Newark, NJ, USA; †Department of Radiology,
University of Medicine and Dentistry of New Jersey, Newark, NJ, USA
DOI: 10.1111/j.1743-6109.2012.02765.x
A B S T R A C T
Introduction. Neither consistent etiology nor treatment have been established for Persistent Genital Arousal
Disorder (PGAD), which is characterized by uninvited, unwelcome, and distressing genital sensation. Sacral (Tarlov)
cysts, which form on dorsal (sensory) roots, most commonly of S2 and S3 in the sacral spine, are reported to produce
genital symptoms that bear similarities to those described for PGAD.
Aims. The present study ascertained the incidence of Tarlov cysts in the sacral spine of women with PGAD
symptoms.
Methods. Women in a PGAD internet support group were asked to submit MRIs of their sacral region to the
investigators, who evaluated the MRIs for the presence or absence of Tarlov cysts.
Main Outcome Measures. The presence or absence of Tarlov cysts at the level of the sacral spine.
Results. Tarlov cysts were present in 12 of the first 18 (66.7%) MRIs submitted to the investigators by women who
suffer from PGAD symptoms. By contrast to this incidence, that of Tarlov cysts reported in the literature for large
samples of the population observed for various disorders (e.g., lumbosacral pain) is 1.2–9.0%.
Conclusion. Tarlov cysts have been described in the literature as producing paresthesias and genital sensory disturbances.
Hence, at least some cases of PGAD might be considered to be a Tarlov cyst-induced paresthesia. Based on
the relatively high occurrence of Tarlov cysts currently observed in women who suffer from PGAD symptoms, it
would seem advisable to suspect Tarlov cysts as a possible organic etiological factor underlying PGAD. Komisaruk
BR and Lee H-J. Prevalence of sacral spinal (Tarlov) cysts in persistent genital arousal disorder. J Sex Med
**;**:**–**.
Key Words. PGAD; Persistent Genital Arousal Disorder; Tarlov Cysts; MRI; Genital Sensory Nerves; Restless
Genital Syndrome
Introduction
Origin of a Clue
This study began serendipitously. A colleague
mentioned to one of us (BRK) that his wife,
diagnosed with Persistent Genital Arousal Disorder,
showed an incidental MRI finding of Tarlov
cysts, and asked if they might produce pelvic vasocongestion
and hence her discomfort. Sacral cysts,
first described by I.M. Tarlov in 1938 [1] are occasionally
found incidentally in the course of radiological
examination of the lumbosacral spine for
various disorders. Review of literature on Tarlov
cysts (also termed, “sacral cysts” [2]) indicated that
they form characteristically at the S2 and S3 dorsal
root ganglia, ballooning out as a result of filling
with cerebrospinal fluid, contain dorsal root nerve
fibers in the wall and/or internal portion of the
cyst, and generate paresthesias. Because the S2
and S3 dorsal roots convey the sensory pudendal
and pelvic nerves, which innervate the external and
internal genitalia (for review, [3]), could they generate
the abnormal sensations characteristic of
PGAD?
What Is Persistent Genital Arousal Disorder?
PGAD is a complex pathology with multiple etiologies
and with variably effective therapies. It is a
1
© 2012 International Society for Sexual Medicine J Sex Med **;**:**–**
perplexing condition characterized by high levels
of genital arousal occurring in the absence of subjective
interest or desire. PGAD sufferers are
women who experience intrusive, unsolicited and
seemingly spontaneous genital arousal that can be
unrelenting. This arousal can persist for hours,
days or even longer, despite attempts to relieve it
with sexual activity or orgasm, which, at best,
provide only brief relief from the symptoms.
Attempts to quell the genital arousal by engaging
in masturbation or sexual activity may lead to brief
relief, no relief, or even more arousal and activation.
First characterized and termed Persistent
Sexual Arousal Syndrome (PSAS) by Leiblum and
Nathan [4,5], the condition was later renamed
PGAD by Leiblum [6] to clarify that the disorder
was a problem of genital, rather than sexual,
arousal.
The following five diagnostic features of the
disorder were characterized by Leiblum and
Nathan [4,5]:
1. The physiological responses characteristic of
sexual arousal persist for an extended period
(hours to days) and do not completely subside
on their own;
2. The signs of physiological arousal do not
resolve with ordinary orgasmic experience, and
may require multiple orgasms over hours or
days to remit;
3. These physiological signs of arousal are usually
experienced as unrelated to any subjective sense
of sexual excitement or desire;
4. The persistent sexual arousal may be triggered
not only by sexual activity, but also by seemingly
nonsexual stimuli or by no apparent
stimulus at all; and
5. The physiological signs of persistent arousal are
experienced as uninvited, intrusive, and
unwanted.
A diagnosis of PGAD is made, based upon the
presence of all five of the previously mentioned
features, when distress is rated as moderate or
severe (a score of 2 or 3 on a scale, in which 0 = no
distress and 3 = extreme distress) [7].Women who
complain of PGAD can be severely distressed,
especially when the symptoms continue for an
extended duration without relief. This property of
PGAD predisposes some women to become
severely depressed and even suicidal [8]. As characterized
by Goldstein et al. [9].
“In our experience, women affected with the
condition are frequently suicidal, socially ostracized,
isolated, frustrated, miserable, embarrassed,
and extremely humiliated.” The shame and embarrassment
attached to the symptoms has likely contributed
to the phenomenon going previously
unrecognized and underreported to health care
providers, which could account, at least in part, for
the absence of reliable data on the prevalence of
PGAD.
In contrast, some women experience persistent
genital arousal as a normal, pleasant, and even
reassuring experience. However, those women
differ from the PGAD sufferers in that their
arousal is neither continuous nor unrelenting, and
does not cause them distress [10,11].
Sensations Associated with PGAD
Complaints by PGAD sufferers have been
described as clitoral tingling, irritation, vaginal
congestion, vaginal contractions, throbbing, pressure,
pain, and in some cases, spontaneous orgasms
[12].
Sensations Associated with Tarlov Cysts
Symptoms of Tarlov cysts include: pain in
perineum, vagina, penis, buttock, leg, lower back,
sacrum, or coccyx, dyspareunia, proctalgia,
bladder dysfunction, urinary incontinence, micturition
disorders, bowel incontinence, radicular
pain (neuralgia), loss of sensibility, muscle weakness
or paresis (partial paralysis), dysesthesias
(abnormal sensations experienced in the absence
of stimulation), paresthesias (burning, pricking
sensations) of thigh or foot, retrograde ejaculation,
and “impotence,” a description based on case
reports and a limited sample size [13–15]. Tarlov
cysts smaller than 1.5 cm diameter have been
reported as asymptomatic. It seems plausible that
despite differences in terminology, there is a
degree of congruence between these two sets of
symptomatology.
Characteristics of Tarlov Cysts
From the descriptions in the literature, Tarlov
cysts evidently develop at the distal limits of the
dural sheath, a thinned extension of the dura
mater, which encapsulates not only the brain and
the spinal cord, but also the dorsal and ventral
nerve roots. The thinned dural sheath, which
includes the epineurium, terminates just at, or
distal to, the dorsal root ganglia. At that point, the
perineurium, which is the distal continuation of
the pia/arachnoid, balloons out under pressure of
the cerebrospinal fluid (CSF), perhaps in part
because of the absence of constraint by the proximally
overlying dura mater. The perineurial wall
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contains spinal nerve root fibers and ganglion cells
[1,16] and the fibers may be present in the cyst
cavity itself [16]. It is described that the neck of
this fluid-filled balloon structure is constricted,
creating a one-way “ball-valve” structure that
allows CSF to enter, but not leave readily. As the
volume of CSF changes in response to postural
and positional changes, e.g., from supine to sitting,
or in response to the Valsalva maneuver, sensory
nerve root fibers in the cyst wall can stretch or
compress against adjacent bone or the nerve roots,
thereby producing abnormal sensations [16]. As
pointed out by Acosta et al. [16] “. . . a great deal of
confusion continues to exist over the precise definition
of Tarlov cysts and their distinction from
other spinal cysts. Tarlov cysts have been referred
to as perineurial cysts, nerve root diverticula,
meningeal cysts, sacral cysts, arachnoid cysts, and
arachnoid pouches.” For the present purpose, we
refer to them as Tarlov or sacral cysts.
Present Hypothesis:Tarlov Cysts Can Generate
PGAD Symptoms
Missing from all the previously mentioned literature
is that at least some cases of PGAD could be
due to pathology of the dorsal spinal roots, which
could generate abnormal, distressing genital sensations.
Therapeutic procedures focused on pelvic
organs or their innervation, e.g., clitoridectomy
[17] or surgical relief of nerve entrapment or
pudendal or pelvic nerve block [9,18] would not
provide relief if the symptoms are generated proximal
to these interventions, e.g., at the dorsal spinal
nerve roots near their entry to the spinal cord.
That is, even if the clitoris is removed or anesthetic
is administered as a nerve block to the distal
portion of the nerve, direct Tarlov cyst-produced
mechanical stimulation of the (unanesthetized
portion of ) the nerve where it enters the spine
could still generate afferent action potentials that
would be perceived as if originating in the genital
region.
Based upon these considerations, we hypothesized
that Tarlov cysts can generate PGAD. We
tested the hypothesis by contacting a specific
PGAD internet support group (Ms. Jeannie Allen,
pers. comm.), asking the women in the group to
send us MRIs of their lower back that they may
have had taken for diagnostic purposes; we then
evaluated the MRIs for existence of Tarlov cysts.
In the general population, the incidence of Tarlov
cysts has been reported as between 1.2% and
9.0%, based upon incidental findings of the cysts
in thousands of cases and in a variety of conditions
for which lumbosacral MRIs were obtained
[2,16,18].
Methods
Approval was obtained from the Institutional
Review Boards for the Protection of Human Subjects
in Research of Rutgers University and the
University of Medicine and Dentistry of New
Jersey (Newark) for evaluating existing MRI
records on a confidential basis, and each of the
women gave written permission for publication of
their MRI images to be made anonymously. We
requested of women in the Internet PGAD
support group hosted by Ms. Jeannie Allen to send
us, postage prepaid, diagnostic MRIs that they had
obtained of their sacral spinal region. Of the more
than 300 women in the internet support group, we
received 18 such MRIs, each of which we evaluated
for the presence or absence of Tarlov cysts, which
occur predominantly at the S2–S3 levels of the
spine, and because they are filled with cerebrospinal
fluid, appear bright on T2-weighted images
and dark on T1-weighted images.
Results
Of the 18 sets of MRIs of the spinal region that we
received from women suffering from PGAD,
Tarlov cysts were clearly evident in 12 (i.e., 66.7%)
(Figures 1 and 2). The MRIs of five women show
one cyst, those of six women show two cysts, and
those of one woman show three cysts. Consistent
with the classical location of Tarlov cysts, all of the
20 cysts in the 12 women were located at the S2
and/or S3 spinal levels; two of which (Figures 1a
and 2j) were at the S1 and/or S2 level. The
spheroidal-shaped cysts ranged in maximum diameter
from 3 mm to 20 mm with a group mean
maximum diameter of 9.6 mm  5.1 (s.d.). In the
13th woman, no Tarlov cyst was evident, but she
had a spondylolisthesis, i.e., the L5 vertebra slid
forward over the S1 vertebra by 25%, distorting
the spinal nerve roots of the cauda equina. In the
14th woman, there was a severe stenosis at L2–L3
compressing the cauda equina. No pathology was
evident in the MRIs of the other four women.
Discussion
Limitations of the Present Methodology
We recognize that the validity of conclusions
based on the present findings is tempered by the
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unconventional means by which the data were
obtained. There was a self-selection process in
which of more than 300 women in the PGAD
support group who were notified via the internet
of our request for MRI images of the lower back,
only 18 women sent us their MRIs that included
images of their sacral spinal region. Thus, we
could not evaluate the MRI images by a blind
procedure. We have no formal control group, but
rather for comparison with our “convenience
sample” of 18 women manifesting a 66.7% incidence
of Tarlov cysts, we rely on the literature that
reports a much lower incidence of Tarlov cysts
(1.2–9%) in the general population of thousands of
patients with MRIs analyzed for lower back problems.
As to whether small sacral cysts might have
been be overlooked in those studies, a coauthor of
the present study (H-JL) was also a coauthor on
one of the previously mentioned studies [18] and
counted even small sacral cysts, finding only 7
cysts among 584 MRIs (1.2%). Despite the limitations,
we believe that the present findings indicate
a sufficiently plausible etiological basis for
PGAD to warrant further investigation.
PGAD Not Previously Linked to Tarlov Cysts
A review of the literature on Tarlov cysts reveals no
mention whatsoever of PGAD, despite multiple
papers published on properties and surgical treatment
of the cysts since 2001, when Leiblum and
Nathan first characterized PGAD. On the other
hand, a review of the literature on PGAD reveals
no mention whatsoever of Tarlov cysts, even
though physiological, as well as psychological, etiologies
have been proposed.
Although multiple clinical reports claim that
Tarlov cysts are asymptomatic unless they are at
least 1.5 cm in diameter, perhaps a less stringent
criterion is required in the case of PGAD symptoms,
which may be paresthetic rather than
painful, and because of the potential underreporting
factor related to social factors. Leiblum
et al. [10] pointed out that PGAD patients often
feel ashamed and embarrassed about revealing
their symptoms. Embarrassment has been emphasized
as a major factor in underreporting of sexual
dysfunctions [19]. Tarlov cysts are frequently
reported as just incidental findings, for they can be
asymptomatic. However, if they produce PGAD,
women may under-report the symptoms due to
embarrassment, thus rendering the cysts only
apparently asymptomatic. This could account, at
least in part, for the lack of previous complaints of
women diagnosed with Tarlov cysts reporting
symptoms of PGAD, by contrast with the current
finding that women who report PGAD symptoms
have a relatively high incidence of previously undiagnosed
Tarlov cysts. Thus, it should not be
assumed, a priori, that a Tarlov cyst less than
1.5 cm diameter would be too small to generate
PGAD symptoms. At present, we cannot relate
size of the cysts to individual women’s symptoms
because we have only reviewed existing MRI
records. Future research will evaluate the possible
relationship between specific spectra of PGAD
symptoms and the presence/size of Tarlov cysts.
Hypotheses of PGAD Etiology
Leiblum [6] postulated that there may be two
subtypes of PGAD: one more closely related to
physiological factors (e.g., neurovascular or
neurochemical), and the other to psychological
factors. In the literature review by Leiblum et al.
[7] the authors concluded that there are multiple
hypotheses, but no consensus, regarding the etiology
of PGAD. They summarized the hypotheses
as: central neurological changes (e.g., postsurgical,
post-injury brain lesion, seizure disorder),
peripheral neurological changes (e.g., pelvic nerve
hypersensitivity or entrapment), vascular changes
(e.g., pelvic congestion or dilatation, or vascular
pathology associated with chronic fatigue syndrome
[20], mechanical pressure against genital
structures, medication-induced changes (e.g.,
upon either initiation or cessation of SSRI or
mood stabilizer therapy), psychological factors
Figure 1 MRI images submitted by 12 different women (a–l) showing evidence of sacral (Tarlov) cysts, out of 18 women with
PGAD symptoms who submitted their sacral MRIs to us. All the images except (g) are T2-weighted; T1-weighted images are
(also in some cases) shown in (g, h, i, and k). The arrows point to the cysts: Image a) sagittal view of three different cysts
at the S1 and S2 levels; b) sagittal and transaxial views of two different cysts at the S2 and S3 levels; c) sagittal and coronal
views of one cyst at the lower S2 level; d) sagittal and transaxial views of one cyst at the S2-S3 junction; e) sagittal and
transaxial view of a double cyst at the S2 and S3 levels; f) sagittal and coronal views of a pair of cysts at the lower S2 and
upper S3 levels; g) T1-weighted images of sagittal and coronal views of three cysts. The T2-weighted images that were
submitted did not include these sacral levels, so are not shown. The first two panels on the left show one cyst at the S2-S3
junction. The three panels on the left show two additional cysts, one (left side) at lower S2 and the other (right side) at upper
S3. Continued in Figure 2.

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Figure 2 Continuation of Figure 1: h) sagittal T1 and T2-weighted images of the same cyst at S2 and a T2-weighted
transaxial view of this cyst (right panel); i) T1- and T2-weighted images of a large cyst at S2 (upper panels) and transaxial
T1- and T2-weighted images of this cyst (lower panels); j) axial T2-weighted image of a cyst at the S1-2 level; not visible in
sagittal view k) T1- and T2-weighted images of a cyst at the S2 level (upper panels) and coronal S2 and “STIR’ images of
the two cysts in this woman (bottom panels); l) sagittal T2-weighted image of a cyst at the S2 level.
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(e.g., severe stress, the perception and persistence
of symptoms, anxiety and obsessive vigilance about
physical symptoms, overall lower levels of sexual
satisfaction, lower desire, and greater pain), beginning
menopause, physical inactivity [7], some
combination of these, and/or idiopathic factors.
Other types of physical etiology were suggested
byWaldinger and Schweitzer [17]; they observed a
close association of PGAD with “restless legs syndrome
(RLS)”, and characterized PGAD as
“. . . the expression of a nonsexually driven hyperexcitability
of the genitals and subsequent attempts
to overcome it by genital manipulations”, the latter
of which are an “. . . imperative urge to suppress
dysesthesias and paresthesias.” Waldinger et al.
[21] related PGAD-like symptoms in two men to
genital hypersensitivity, which they attributed to
“small fiber sensory neuropathy” of the pudendal
nerve. In light of the possible involvement ofTarlov
cysts in producing PGAD symptoms, and the fact
that the S1 and S2 spinal nerve roots control the
posterior dermatomes of leg sensation and movement
(e.g., [22]), the possibility should be considered
thatTarlov cyst-induced irritation of the spinal
nerve roots S1 and S2 could interact with, and
contribute, at least in part, to the cerebral component
of RLS. In a follow-up study, we plan to
ascertain whether specific symptoms of PGAD,
e.g., RLS, are correlated with the existence or
absence of Tarlov cysts, at least in the women who
comprise the sample in the current analysis.
Goldstein et al. [9] observed that “. . . persistent
sexual arousal syndrome has much in common
with stuttering or recurrent [clitoral] priapism” in
women with idiopathic symptoms of the syndrome,
and hypothesized an “unusual genital
tissue biochemistry” as the etiology. But ultimately,
they suggested that most patients with
“persistent sexual arousal syndrome” should be
classified into the category “idiopathic” because,
“. . . for the most part, clearly recognized causes
for the syndrome are limited” [9] and in their own
survey of 76 women who fulfilled all the criteria of
PGAD, Leiblum et al. [7] found “no evidence of
specific major medical illness or pharmacological
agents effects associated with the report of
PGAD.” Thus, there appears to be no known
unitary etiology for PGAD.
Current PGAD Therapies
In a comprehensive literature review and recommendations
for management of PGAD, Goldmeier
et al. [11,23] emphasized taking: (i) a psychiatric
history; (ii) a full medical history including medications;
(iii) a comprehensive genital and pelvic
examination; and (iv) a pelvic ultrasound. They
emphasized this approach in order to exclude local
pathology, such as genital dermatosis and genital
prolapse, and to exclude conditions such as pelvic or
cerebral pathology. Regarding the latter, a speculation
of a neurological epileptic basis for PGAD [9]
was followed by a finding that epileptic activity was
temporally associated with a patient’s symptoms,
and anti-epileptic treatment suppressed both her
orgasmic seizures and symptoms of PGAD [24].
Using a different approach, repeated sessions of
electroconvulsive shock were reported to ameliorate
PGAD symptoms [25]. Waldinger et al. [26]
reported, in two clinical cases, good therapeutic
effects against PGAD and restless legs symptoms
by using TENS stimulation. Perhaps in
Waldinger’s two cases, the effectiveness against the
symptoms was due to an effect originating at the
same sacral region as that affected pathologically by
Tarlov cysts.
Other therapeutic PGAD interventions have
focused on symptom management. “Psychoeducation”
and social support impress on the patients
that they are not alone in their experience with
PGAD. Patients were trained to distract themselves
from focusing on their genital sensations
and to become aware of the triggers that worsen
symptoms. Cognitive–behavioral interventions
have been used to enhance coping skills and assist
in interrupting the cycle of anxiety and catastrophizing
of the symptoms [7]. Anesthetizing agents
have been applied to numb the genital area.
Neither clitoridectomy [27], local anesthesia, nor
peripheral pudendal nerve block would be
expected to alleviate PGAD symptoms if the
symptoms were generated proximally at the spinal
level, e.g., by Tarlov cysts. Pelvic massage or
stretching exercises provided by a specialist in
pelvic floor physical therapy have been applied to
reduce or eliminate the pelvic tension and break up
connective tissue strictures that might contribute
to the condition [6,8]. Medication has been
applied by trial and error, as certain medications
may be associated paradoxically with either alleviation
or activation of the symptoms. Mood stabilizing,
antiseizure medications such as valproic acid,
or SNRIs (Selective Norepinephrine Reuptake
Inhibitors) have been tried [6,8]. In light of the
current findings, it would seem advisable to add a
diagnostic sacral spinal MRI to the PGAD therapy
armamentarium. To our knowledge there are no
reports in the literature of amelioration of PGAD
symptoms by treatment of Tarlov cysts.
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Potential Value of MRI to Test for Presence of
Tarlov Cysts in Cases of PGAD
The present finding that 66.7% of the 18 women
with PGAD who sent us their spinal MRIs have
one or more Tarlov cysts in their sacral spine far
exceeds the population average, which has been
reported to range from 1.2% to 9% [2,6,18,28].
Langdown et al. [2] found that 54 of 3,535 (1.5%)
patients showed Tarlov cysts in MRI scans for
lumbosacral symptoms; 70% were women. Similarly,
Oaklander et al. [28] reported that 1.8% of
1,305 lumbosacral scans showed Tarlov cysts, of
which 75% were in women. In an international
survey of persons with Tarlov cysts, women outnumbered
men by 9:1; the predominant age of all
respondents was 40–60 [29,30]. While PGAD is
likely to have a variety of etiologies, the prevalence
of Tarlov cysts in the present population indicates
that in the absence of any other identified pathology
related to a woman’s PGAD symptoms, it
would seem reasonable and advisable to test
whether a Tarlov cyst is generating the PGAD
symptoms.
Therapy for Tarlov Cysts
Probably the most convincing evidence as to
whether a Tarlov cyst is generating the PGAD
symptoms would be administration of an epidural
anesthetic block at the sacral spinal level, which, if
the Tarlov cyst is responsible for the PGAD symptoms,
should eliminate the symptoms for the brief
duration of the block, with return of the symptoms
thereafter. If the PGAD symptoms are reversibly
blocked by this epidural procedure, there are a
number of long-term surgical procedures that
could then be applied, although variable success
has been claimed for surgical treatment of Tarlov
cysts. As the most recent example, Murphy et al.
[31] surgically treated symptomatic Tarlov cysts by
CT fluoroscopic-guided needle aspiration of the
cerebrospinal fluid, followed by fibrin “glue” injection;
they claim they have not had any case of
aseptic meningitis as a potential side effect of this
procedure [31]. Other techniques for treating
Tarlov cysts include subarachnoid drain, cyst fenestration
and imbrication, muscle graft over the
fenestrated cyst, cyst wall resection, and closure
with myocutaneous flap reinforcement to prevent
cyst recurrence or CSF leakage. A more drastic
procedure is resection of the cyst and adjacent
nerve roots, but this can result in neurological
deficit [16]. For a concise summary of surgical
treatments of Tarlov cysts, see Young [32]. A relatively
recent procedure used in chronic pain
patients is intrathecal catheterization with an
implanted pump whose dose and timing of medication
delivery is controlled by the patient [30].
This procedure has apparently not been reported
to be used in the case of Tarlov cysts, but it would
appear to be feasible if the cyst is situated superior
to the filum terminale. There are risks associated
with the procedure, e.g., movement of the catheter,
CSF leakage, infection, etc. [30].
Characteristics of Tarlov Cysts and Other
Spinal Pathologies
Tarlov cysts are just one of several types of spinal
cysts. While it is likely that the pathologies in the
MRIs in Figures 1 and 2 are indeed Tarlov cysts,
other intraoperative and/or histological procedures
are necessary for differentiation of the
several types of cyst. For example, Tarlov cysts
show delayed filling on myelography because of
their constricted, valve-like neck, which renders
them non-compressible when tested intraoperatively
[16]. They develop between the endoneurium
and perineurium at, or distal to, the dorsal
root ganglion. Their lining contains nerve fibers
and/or ganglion cells. By contrast, meningeal
diverticula freely communicate with the subarachnoid
space, are situated proximal to the dorsal root
ganglion, and possess a lining composed of arachnoid
mater and dura mater devoid of neural tissue
[16]. Histopathological examination of eight specimens
of Tarlov cysts demonstrated nerve fibers in
75%, ganglion cells in 25%, and evidence of old
hemorrhage in 50% [13].
It is important to note that Tarlov cysts can
occur in association with other spinal degenerative
pathologies that could produce the symptoms,
such as intervertebral disc prolapse or a stenosis
that compresses the nerve root, sacral bone
erosion which can produce an “insufficiency fracture,”
spondylolisthesis (vertebral displacement),
etc. [2].
Etiology and Mechanism of Action of
Tarlov Cysts
No definitive etiology or mechanism of action has
been established for Tarlov cysts; it has been suggested
that they form as a result of congenital
weakness of the meninges (perhaps more fundamentally
related to connective tissue abnormalities)
combined with subsequent acute physical
trauma [33]. Trauma to the sacrum in the form of
a skiing or motor vehicle accident, or heavy lifting
or straining, were reported in the history of 5 of 10
patients who developed Tarlov cysts [13]. Perhaps
the combination of the congenital and physical
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trauma factors can create a torsion defect specifically
in the unique “weak-spot” just where the
distal extension of the dura mater, i.e., the dural
sheath, ends at the dorsal root ganglion, thus
allowing the Tarlov cyst to form.
We are not aware of any direct evidence as to
the mechanism(s) by which Tarlov cysts produce
their symptoms. It would seem plausible that their
sensory and/or motor (including autonomic, thus
perhaps circulatory and/or vascular) effects could
be produced by the mechanical irritation of
sensory and/or motor nerve roots and/or the ganglion
cells in the wall and/or the interior of the
cyst, and/or by the cyst wall exerting force on the
surrounding nerve roots, bone, or other tissue.
Conclusion
The lack of clear understanding of the etiology
and mechanisms underlying PGAD has prevented
the application of a rationale-based therapy. While
PGAD may well be a complex pathology with
multiple etiologies, the present findings provide a
clue as to a plausible organic pathology—sacral
(Tarlov) cysts—that has evidently not been
reported in the literature previously. It is too early
to know whether, and if so which, symptoms of
PGAD can be accounted for by these aberrant
nerve fiber-containing cysts on the genital and leg
sensory nerve roots in the sacral spine, but in the
present study, the unusually high (66.7%) incidence
of the cysts in women suffering from
PGAD, much higher than the incidence of these
cysts in the general population (up to 9%),
strongly suggests that it would be worthwhile to
test their possible role. In seeking the etiology and
treatment for PGAD for a sufferer, it would seem
advisable to test for—at the very least to rule
out—Tarlov cysts.
Acknowledgment
We dedicate this study to the pioneer of PGAD—our
dear friend and colleague, Professor Sandra Leiblum—
whose tragic and untimely death is a terrible loss. We
gratefully acknowledge the excellent advice and helpful,
critical commentary byWalter Fanburg, MD, and Doctoral
Candidates Nan Wise and Eleni Frangos.
Corresponding Author: Barry R. Komisaruk, PhD,
Department of Psychology, Rutgers University, 101
Warren St, Newark, NJ 07102, USA. Tel: 973-353-
5834; Fax: 973-353-1191; E-mail: brk@psychology.
rutgers.edu; brk@andromeda.rutgers.edu
Conflict of Interest: None.
Statement of Authorship
Category 1
(a) Conception and Design
Barry R. Komisaruk
(b) Acquisition of Data
Barry R. Komisaruk
(c) Analysis and Interpretation of Data
Barry R. Komisaruk; Huey-Jen Lee
Category 2
(a) Drafting the Article
Barry R. Komisaruk; Huey-Jen Lee
(b) Revising It for Intellectual Content
Barry R. Komisaruk; Huey-Jen Lee
Category 3
(a) Final Approval of the Completed Article
Barry R. Komisaruk; Huey-Jen Lee
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