INTRODUCTION
Cerebrospinal fluid fistula (CF) is a complication present in 30% of the skull base surgeries and should be correctly diagnosed in order to prevent severe complications, such as for example, meningitis. In the past decades, Otorhinolaryngologists have played an important role in the diagnosis and treatment of such entities through the correction of fistula by means of extracranial techniques that are considered less complex surgeries when compared to intracranial procedures, reducing postoperative morbidity and mortality.
The purpose of the present study was to report a case of pseudo CSF fistula as a postoperative complication of a skull base surgery, its probable pathophysiology, diagnosis and treatment.
REVIEW OF LITERATURE
Cerebrospinal fluid (CSF) rhinorrhea is defined as the presence of CSF in the nasal cavity and implies existence of a bone or dural opening placing in communication the subarachnoid and the contaminated cavities of the upper airway tract. It is manifested especially by unilateral hyaline rhinorrhea, which can progress to meningitis. Lewin (1954) reported that the incidence of meningitis in cases of CSF rhinorrhea is 25%, even in those in which it has ceased spontaneously1. Leech and Paterson (1973) reported an incidence of 9% of meningitis in CSF rhinorrhea 2.
CSF leaks (CF) can be classified as traumatic and non-traumatic. Traumatic leaks are the most common ones and they are normally associated with cranial facial trauma. They can also be secondary to surgical access to the skull base or microendoscopic surgeries for the treatment of nasosinusal diseases. Despite the development of neurosurgical techniques, CF are observed in about 30% of the skull base surgeries3. Non-traumatic leaks are less frequent. They can be caused by CSF hypertension or can be present in normal pressure CSF as a result of congenital factors4.
The symptoms of patients with CSF leak are clear, hyaline rhinorrhea, usually unilateral, which worsens with physical exercises, cough, sneezes and changes in head position. Repetitive meningitis without apparent cause can be part of the clinical manifestation5.
Complementary exams are important for the correct diagnosis. Head and paranasal sinuses computed tomography with CSF contrast (cisternotomography) can demonstrate the leak site in 46 to 81% of the cases, according to various authors6, 7.
The glucose dosage in nasal secretion presents high diagnostic acuity for CSF rhinorrhea. If glucose concentration is greater or equal to 30mg/dl in the tested liquid, it confirms the presence of CSF rhinorrhea in patients with normal glucose levels5, 8, 9. The test with glucostrips, conversely, is not recommended, since it presents a great number of false positive results. According to Calcaterra (1980), glucostrips can have positive reaction in face of a small amount of glucose, leading to misclassification of CSF, such as for lachrymal secretion or nasal discharge9.
In case of suspicion of CSF rhinorrhea, it is important to consider the differential diagnosis of the pathology, such as for example, vasomotor rhinosinusitis that can simulate a CSF leak and if not correctly diagnosed, it can lead to invasive procedures and even surgical interventions for the correction of the pseudo leak. The glucose dosage in nasal secretion is always below 30mg/dl in cases of pseudo fistula.
Vasomotor rhinitis results primarily from an autonomic dysfunction. The prevalence of the parasympathetic system can be induced by central or peripheral stimulation. It is important to know the anatomy and physiology of the nasal autonomic innervation for the identification of the possible cases of vasomotor rhinitis. Parasympathetic pre-ganglionar fibers of the nasal mucosa arise from the cellular bodies of the upper salivary nucleus and emerge from the brainstem via intermediate nerve. The fibers leave the geniculate ganglion to form the superficial major petrous nerve, and upon emerging from the temporal bone, they are gathered in the profound petrous nerve to form the vidian nerve. The parasympathetic fibers make synapses in the pterygoidpalatine ganglion and are distributed to the nasal mucosa and lachrymal glands, in which they supply the secretory-motor system. The sympathetic fibers arise from the lateral horns of the gray matter of the first and second thoracic segments of the medulla and make synapses in the upper cervical ganglion. The demyelinized post-ganglion fibers form the periarterial plexus around the internal carotid artery and form the profound petrous nerve that is gathered at the superficial major petrous forming the vidian nerve. These fibers pass by the pterygoidpalatine ganglion in which they do not make synapses and are distributed by the nasal mucosa. The nasal sympathetic supply is directed especially to the vascular system and in small amounts to the glands3, 10.
The stimulation of the sympathetic cervical chain produces nasal mucosa vasoconstriction, which is abolished after the section of the vidian nerve. It demonstrates that the vidian nerve is the most important tract for the sympathetic innervation of the nasal mucosa. Conversely, the stimulation of parasympathetic fibers cause cavernous tissue nasal congestion and fluid secretion production11.
Abnormalities of emotional status, fatigue and pain can cause hypothalamic stimulation that causes an excess of parasympathetic stimulation producing a nasal vasomotor reaction. The other possible mechanism is the stimulation of the main parasympathetic ganglion: the pterygoidpalatine ganglion12. Krajina and Poljak (1975) suggested that vasomotor rhinitis could result from the stimulation of the ganglion even by external stimuli. Bleeding of the ganglion could be a possible stimulus13.
Nasal trauma resulting from septoplasty, rhinoplasty and nasal fractures could act as potential etiological factors to cause vasomotor rhinitis 12, 14. Segal et al. (1999) demonstrated a statistically significant difference in frequency of vasomotor rhinitis among patients that presented nasal trauma and the control group12. Beekhuis (1976) reported a 10% occurrence of vasomotor rhinitis in patients submitted to rhinoplasty 14.
CASE REPORT
NPS patient, aged 52 years, female, was admitted to Hospital das Clinicas, UFMG, in March 1998 with clinical picture of acromegalia for six years. The serum hormone dosage confirmed the increase in growth hormone (62 mg%) whereas the other hypophysis functions were preserved. Magnetic resonance imaging revealed hypophysis macroadenoma. The patient was submitted to surgical exeresis of the tumor. The transseptosphenoid access to the hypophysis was conducted by the Otorhinolaryngology team. During the surgical procedure, the tumor mass was removed, and there was no CSF leak, so we closed the fossa hypophysial with fat fragments and Surgicelâ and the sphenoid sinus with bone fragments.
The patient presented hyaline rhinorrhea in the early postoperative period, which led to the suspicion of CSF leak.
Skull base and hypophysial fossa CT scan with intrathecal contrast conducted then did not show CSF leak to the sinuses. The glucostrip test was positive, but the dosage of glucose in the nasal liquid was 10mg/dl, a value considered within the normal range. We also noticed that there was no increase in nasal liquid drainage with Valsalva maneuver. Owing to such findings, we suspected of a pseudo CSF leak and decided to follow clinical treatment with intranasal ipatropium bromide. The patient presented improvement of symptoms within 24 hours and remained asymptomatic in the control visits up to 2 months after treatment. From an endocrine perspective, she presented hypothyroidism, but the other hormones were within the normal serum levels. The last dosage of growth hormone was also normal (2.4 mg/dl). There was improvement of the characteristics of acromegalia. Magnetic resonance imaging showed preserved hypophysis and no tumor recurrence.
Discussion
CSF leak is a complication present in about 30% of the skull base surgeries3. Correct diagnosis and treatment are important to prevent complications. The symptoms of patients with CSF leak are clear, hyaline rhinorrhea, usually unilateral and worsened upon physical stress, cough, sneeze and change in head position. The patient in our case study presented symptoms simulating a fistula in the early postoperative period of hypophysis adenoma surgery.
Complementary tests in such case were important for the definition of the diagnosis. Paranasal sinuses CT scan with injections of CSF contrast can demonstrate the fistula site in 46 to 81% of the cases6, 12. In this case, the CT scan performed did not show a fistula, which did not exclude the diagnosis. Glucose dosage below 30mg/ml in nasal secretion is essential for the diagnosis of pseudo fistula since this test presents high diagnostic acuity and concentrations above or equal to 30mg/ml confirm the presence of CSF rhinorrhea in patients with normal glucose levels5, 8, 9.
There are few cases of vasomotor rhinitis related with surgical trauma reported in the literature. Segal et al. (1999) demonstrated statistically significant difference in frequency of vasomotor rhinitis between patients that had nasal trauma and the controls12. Beekhuis (1976) reported the occurrence of 10% of vasomotor rhinitis in patients submitted to rhinoplasty 14. The authors believe that the nasal trauma that caused surgical access in this patient had led to anatomical compromise of the nasal tissues, which resulted in direct stimulation of the parasympathetic system or sympathetic dennervation, causing the vasomotor rhinitis.
The treatment of pseudo leak is successfully made with parasympathetic blockers of atropine and ipatropium bromide that restore the autonomic balance of the nasal mucosa. A good response to treatment reinforces the correct diagnosis.
CLOSING REMARKS
Otorhinolaryngologists and neurosurgeons should be attentive to the fact that postoperative hyaline rhinorrhea can be a vasomotor rhinitis, characterizing a CSF pseudo leak. The differential diagnosis can prevent invasive procedures and even unnecessary surgeries.
Nasal secretion glucose dosage in suspected cases of CSF leak is an important diagnostic tool and should be, whenever possible, conducted before the corrective surgery. The therapeutic trial should be conducted for diagnostic confirmation in case of suspicion of vasomotor rhinitis.
ReferENCES
1. Lewin W. Cerebrospinal fluid rhinorrhea in closed head injuries. Br J Surg 1954;42:1-18.
2. Leech PJ, Paterson A. Conservative and operative management for cerebrospinal-fluid leakage after closer head injury. Lancet 1973;12:1013-6.
3. Cusimano MD, Sehkar LN. Pseudo-cerebrospinal fluid rhinorrhea. J Neurosurg 1994;80:26-30.
4. Ommaya AK, Di Chiro G, Baldiwin M, Pennybacker JB. Non traumatic cerebrospinal fluid rinorrhea. J Neurosurg Phys 1968;31:214-25.
5. Hubbard JL, Mc Donald TJ, Pearson BW, Laws ER. Spontaneous cerebrospinal fluid rhinorrhea evolving concepts in diagnosis and surgical management based on the experience from 1970 through 1981. Neurosurgery 1985;16:314-21.
6. Manelfe C, Cellerier P, Sobel D, Prevost C, Bonafe A. Cerebrospinal Fluid Rhinorrhea: evolution with metrizamide cisternography. AJR 1982;138:471-6.
7. Prere J, Puech JL, Derroover N, Arrue Ph et al. Rhinorrhea and meningitis due to post-traumatic osteo-meningeal defects in the anterior cranial fossa. Diagnosis with water - soluble CT cisternography. J Neuroradiology 1986;13:278-85.
8. Beckhardt R N, Setzen M, Carras R. Primary spontaneous cerebrospinal fluid rhinorrhea. Otolaryngol Head Neck Surg 1991;104:425-32.
9. Calcaterra TC. Extracranial surgical repair of cerebrospinal rhinorrhea. Ann Otol Rhinol Laryngol 1980;89:108-16.
10. Lang J. Clinical Anatomy of the Nose, Nasal Cavity and Paranasal Sinuses. 1ª ed. Stuttgart: Thieme Medical Publishers; 1989. p. 112-5.
11. Malcomson KJ. The vasomotor activies of the nasal mucous membrane. J Laryngol Otol 1959;73:73-98.
12. Segal S, Berenholz L, Shlamkovitch N et al. Vasomotor rhinitis following trauma to the nose. Ann Otol Rhinol Laryngol 1999;108:208-11.
13. Krajina Z, Poljak Z. Relationship between the vegetative inervation and the sensibility of the nasal mucosa. Acta Otolaryngol (Stockh) 1975;79:172-5.
14. Beekhuis GJ. Nasal obstrucion after rhinoplasty: etiology and techiniques for correction. Laryngoscope 1976;86:540-8.
1 Joint Professor, Department of Ophthalmology, Otorhinolaryngology and Speech and Language Pathology and Audiology,
Medical School, University of Minas Gerais UFMG.
2 Joint Professor, Department of Ophthalmology, Otorhinolaryngology and Speech and Language Pathology and
Audiology, Medical School, University of Minas Gerais UFMG.
3 Master in Neurosurgery. Neurosurgeon of Hospital das Clínicas, UFMG.
4 Doctorate studies in Otorhinolaryngology under course. Preceptor of Hospital das Clínicas - UFMG.
5 Assistant Professor, surgeon of the Department of Ophthalmology, Otorhinolaryngology and Speech and
Language Pathology and Audiology, Medical School, University of Minas Gerais UFMG.
6 Resident Physician, Otorhinolaryngology, Hospital das Clínicas- UFMG.
Department of Ophthalmology, Otorhinolaryngology and Speech and Language Pathology and Audiology, Medical School, University of Minas Gerais UFMG.
Address correspondence to: Roberto Eustáquio Santos Guimarães - Avenida Pasteur, 88 4º Andar Belo Horizonte MG 30150-290
Tel/fax: (55 31) 3222-2891 - E-mail: rguimaraes@ alcance.com.br
Article submitted on February 19, 2002. Article accepted on April 24, 2002.
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