Romanian Neurosurgery (2011) XVIII 3: 279 – 285 279 Intracranial hypotension Şt.M. Iencean Neurosurgery, Emergency Clinical Hospital “Prof. Dr. N. Oblu” Iaşi, Romania Abstract the case of chronic subdural hematomas). The intracranial hypotension is the The decrease in the volume of the decrease in the intracranial pressure caused cerebral parenchyma, by various by the decrease in the volume of the mechanisms – senile cerebral atrophy, cerebrospinal fluid secondary to the CSF surgical resection, etc., does not generate loss. The intracranial hypotension is first of all an intracranial hypotension characterized by an orthostatic cephalea, not syndrome, but there may be focal calmed by antalgics accompanied by nausea, neurological symptoms depending on the vomiting, vertigos, diplopia, etc. The suffering cerebral areas. The volume of the diagnosis is confirmed by a lumbar diminished cerebral parenchyma is manometry and by the performed progressively diminished by gliosis and/or paraclinical explorations (cerebral CT, by CSF; therefore, the intracranial pressure cerebral MRI). is maintained at normal values. The The intracranial hypotension treatment decrease in the intracranial sanguine is - etiologic, and it consists in closing the volume by arterial hypotension leads to the CSF fistula; pathogenic, which consists in decrease in the cerebral perfusion pressure recreating the normal CSF volume, and with ischemic phenomena; this may also symptomatic, which refers to the treatment lead to a decreased CSF secretion, but the of the symptoms related to intracranial intracranial pressure decrease seems to be hypotension. less important than ischemia. The surgical Keywords: cerebrospinal fluid, CSF removal of a pathologic volume produces a fistula, intracranial hypotension, intracranial sudden decrease in the endocranial volume pressure and in the intracranial pressure, also known as the surgical cerebral-ventricular collapse, Introduction and which is rapidly compensated from a therapeutic point of view. Once the The intracranial hypotension represents neurosurgical intervention has been the intracranial pressure decrease; it may be performed, the endocranial cavity is no generated by the decrease in the volume of longer a close environment, and there is no any of the intracranial components: the correspondence between the intracranial cerebral parenchyma, the cerebrospinal hypotension and the surgical cerebral fluid, and the sanguine content and/or by collapse. Therefore, of the three intracranial the rapid removal of a pathologic volume components, only the diminished volume under the circumstances of a pressure of the cerebrospinal fluid intervenes in the equilibrium achieved by the efficient generation of the intracranial hypotension. compensating mechanisms (especially in (Figure 1). 280 Şt.M. Iencean Intracranial hypotension Figure 1 Scheme of the meningeal layers Figure 2 The ventricular system – schematic drawing The intracranial hypotension is, coughing, laughing, the Valsalva maneuver, therefore, the decrease in the intracranial which is not calmed by antalgics and is pressure caused by the decrease in the accompanied by nausea, vomiting, vertigos, volume of the cerebrospinal fluid secondary diplopia, etc. The diagnosis is confirmed by to the CSF loss (Figure 2). The intracranial a lumbar manometry and by the performed hypotension is characterized by an paraclinical explorations (cisternography, orthostatic cephalea, exacerbated by cerebral CT, cranial-cerebral RMN). Romanian Neurosurgery (2011) XVIII 3: 279 – 285 281 From a clinical perspective, the the explorations prove the existence of intracranial hypotension may be several arachnoid fissures at the level of the represented as: spinal radicular sheath, or the case of the - an acute form, with a violent occult nasal CSF fistula. symptomatology present in clinostatism, • There have been cases of intracranial and which may evolve towards psychic hypotension without the identification of a disorders and the modification of the dural lesion in situations of dehydration, conscience state, diabetic coma, uremia, or severe systemic - a sub-acute form with absent illnesses. symptoms or of a reduced intensity in There are two theories concerning the clinostatism; they occur or they are mechanism leading to the intracranial exacerbated in orthostatism, hypotension symptomatology: - a chronic, frequent form, with a - the decrease in the volume of symptomatology occurred in orthostatism, cerebrospinal fluid leads to movements of of smaller, bearable intensity and a tiresome the endocranial structures with the traction feeling that may allow the development of of the formations that contain pain an activity, but with a reduced efficiency receptors: meninx, draining veins to though. sinuses, trigeminus, glossopharyngeal and vague nerves, as well as the first cervical Etiology and pathogeny spinal nerves. Orthostatism increases the The decrease in the normal CSF traction of these structures, emphasizing quantity in the cranial-spinal space may be the symptomatology. generated by: - the decrease in the CSF volume leads • the persistence of a dural continuity to the intracranial pressure decrease and, solution and the most frequent causes are therefore, according to the Monro–Kellie the following ones: theory, a dilatation of the intracranial - operations involving the lumbar vascular structures is produced, which puncture: the exploratory lumbar puncture, generated the accentuated cephalea in myelography, myelo-CT, rachianesthesia, orthostatism. Moreover, there is a dilatation - cranial-spinal traumatisms with the of the spinal epidural veins, explaining the generation of a CSF fistula, spinal radicular pains. - cranial-cerebral neurosurgical or spinal It is currently considered that these two interventions, mechanisms are concomitant, they act - extremely rarely, by a spinal anterior- together and they justify the lateral CSF fistula in thoracic surgery, symptomatology. • decrease in the CSF secretion by various mechanisms (after radiotherapy, Clinical presentation senile, etc.) The main symptom of the intracranial • reduced CSF quantity by a hypotension is the orthostatic cephalea: a ventricular-peritoneal drainage, cephalea that occurs or is emphasized in • the so-called “spontaneous” orthostatism. The characteristics of the intracranial hypotension, when none of the cephalea vary from one patient to another, above-mentioned causes is underlined, but but the common element is the fact that it 282 Şt.M. Iencean Intracranial hypotension is exacerbated in the orthostatic position, at may exclude other pathology and confirm a coughing effort, when laughing, etc., and the intracranial pressure decrease. In the it is not influenced by antalgics. context of certain maneuvers that include Vertigo is the nest symptom from the the lumbar puncture (myelography, myelo- frequency point of view, vertigos that occur CT, rachianesthesia), the occurrence of a or are accentuated in orthostatism too. clinical syndrome that announces the There may also be feelings of nausea, intracranial hypotension does not require vomiting, tingles, facial paresthesias, and the performance of other investigations in radicular pains at the level of the superior the case of a patient who has already limbs, all of them being emphasized in undergone a cranial-cerebral exploration. orthostatism. In the case of cranial-cerebral or spinal The establishment of how severe the traumatisms, the investigations performed symptomatology is and of the etiology in order to establish the traumatic lesions makes the distinction between the clinical underline the dural lesion. forms: acute, sub-acute and chronic. The occurrence of the symptomatology In the chronic form of intracranial at temporal distance from a particular hypotension, symptoms are accentuated in situation, which suggests the existence of a orthostatism, and they diminish or persistent dural fistula, requires the disappear in clinostatism. Sometimes, performance of certain explorations that symptoms have a reduced intensity with the may establish the diagnosis. It is considered presence of an accentuated feeling of that the testing of a patient with chronic asthenia. Based on the dominating cephalea by arranging him or her in a symptom, there are forms which are mainly Trendelenburg position, followed by the cephalalgic, vertiginous, paresthesic, with improvement of the cephalea, suggests a vegetative disorders, etc. possible occult CSF fistula and it requires In the sub-acute form, symptoms are supplementary explorations. manifested in the horizontal position, and The intracranial pressure measurement they are exacerbated in orthostatism with an establishes the diagnosis, but it must be invalidating effect. performed after the cranial-cerebral The acute form is characterized by an explorations that exclude another accentuated symptomatology, which is pathology. The cerebrospinal fluid has a present in clinostatism, with vomiting, to quasi-normal composition; sometimes, dehydration, photophobia, sometimes even there may be an increase in the convulsive crises. Moreover, there may be cerebrospinal fluid proteins, lymphocytosis; psychic disorders or even modifications of erythrocytes may be present, with a the conscience state. The acute form is very xanthochromic aspect. rarely registered nowadays. The cranial-cerebral computer tomography may prove the erasure of the Explorations basal cisterns without the existence of a The intracranial hypotension diagnosis cerebral