LOW CEREBROSPINAL FLUID HEADACHE

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CHAPTER 62 LOW CEREBROSPINAL FLUID HEADACHE

BACKGROUND AND TERMINOLOGY

In 1938, Schaltenbrand used the term aliquorrhea to describe the spontaneous occurrence of an entity manifested by very low cerebrospinal fluid (CSF) opening pressures and orthostatic headaches, among other features.1,2 Sometimes referred to as Schaltenbrand’s headaches, this later came to be known as spontaneous intracranial hypotension.3 It is now realized that practically all cases of spontaneous intracranial hypotension result from spontaneous CSF leaks,4 often at the level of the spine (particularly the thoracic spine5) and only rarely at the skull base. CSF leak leads to CSF volume depletion. Terms such as spontaneous CSF leak, CSF hypovolemia, and CSF volume depletion have been used interchangeably with spontaneous intracranial hypotension, because some patients with this disorder have consistently normal CSF opening pressures.5,6 True hypovolemic state (reduced total body water), CSF shunt overdrainage, dural holes or tears as the result of lumbar puncture, epidural catheterization, surgery, and trauma all may lead to loss of CSF volume. In this chapter, we focus on spontaneous CSF leaks.

CLINICAL MANIFESTATIONS

Headache is the most common manifestation. It is “classically” orthostatic (present in upright position, relieved by recumbency).3,5 It is often not throbbing, but it may be throbbing; it is often bilateral, but it may be unilateral; and it is often aggravated or sometimes even triggered by Valsalva-type maneuvers. The headache may be frontal, fronto-occipital, holocephalic, or occipital. Not all headaches in CSF leaks are orthostatic, and variability is substantial (Table 62-1).5,1317 Furthermore, not all orthostatic headaches result from CSF leaks. For example, they can be the dominant clinical manifestation in some patients with postural tachycardia syndrome.18

TABLE 62-1 Headache Variations in Cerebrospinal Fluid (CSF) Leaks

MRI, magnetic resonance imaging.

CLINICAL MANIFESTATIONS OTHER THAN HEADACHES

Many of the patients with spontaneous CSF leaks have one or, often, more symptoms in addition to the headaches (Table 62-2).3,5,1932

TABLE 62-2 Clinical Features Other Than Headaches

Rare manifestations: facial numbness or weakness, diplopia due to third or fourth cranial nerve palsy,2023 galactorrhea,24 Menière’s disease–like manifestations,25 upper limb radiculopathy,26 encephalopathy,27 stupor,28 coma,29 parkinsonism,30 ataxia, incontinence, gait unsteadiness,31 frontotemporal dementia32

Proposed mechanisms of clinical manifestations in CSF leaks and intracranial hypotension are listed in Table 62-3.3,5,1934

TABLE 62-3 Mechanisms of Clinical Manifestations or Cerebrospinal Fluid Volume Depletion

Clinical Manifestation Proposed Mechanism
Headache Descent of the brain, stretch and distortion of pain-sensitive suspending structures of the brain3,5,33,34,34a
Cranial nerve palsies Stretching or compression of related cranial nerves1923
Dizziness, change in hearing Stretching of eighth cranial nerve or pressure changes in perilymphatic fluid of the inner ear5,25
Galactorrhea and increased prolactin Distortion of pituitary stalk24
Radicular upper limb symptoms Stretching of cervical nerve roots or irritation by dilated epidural venous plexus5,26
Encephalopathy, stupor, coma Diencephalic compression2729
Cerebellar ataxia, parkinsonism Compression of posterior fossa and deep midline structures30
Frontotemporal dementia Compression of frontotemporal lobes32
Gait disorder Spinal cord venous congestion31

DIAGNOSIS

Radioisotope Cisternography

Indium 111 is the radioisotope of choice. This is introduced intrathecally, typically through a lumbar puncture, and its movement is monitored by sequential scanning at various intervals, up to 24 or even 48 hours. Normally, by 24 hours (but often earlier), substantial radioactivity can be detected over the cerebral convexities. When a spinal CSF leak exists, the activity typically does not extend much beyond the basal cisterns. Therefore, images at 24 or even 48 hours reveal either absence or paucity of activity over the cerebral convexities.3537 This finding is the most common cisternographic abnormality in CSF leaks. Detection of parathecal activity that may point to the level or approximate site of the leak, although more desirable, is noted much less commonly (Fig. 62-1). Furthermore, meningeal diverticula, if large enough, may appear as foci of parathecal activity. Another cisternographic observation in CSF leaks is the early appearance of radioactivity in the kidneys and urinary bladder (<4 hours versus 6 to 24 hours), indicative of early entrance of extravasated isotope into the venous system and its early renal clearance and early appearance in the urinary bladder.