DISCUSSION:
ISH is a rare complication of spinal
anesthesia. About 41 % of
postpartum ISH becomes chronic and the ratio of acute (31%) and
subacute (33%) subdural hematomas (SDH) are similar3.
While the exact incidence of ISH following spinal anesthesia is unknown,
as patients are usually treated conservatively without any
investigations and reporting, it
is known that the incidence of intracranial subdural hematoma following
this anesthesia is 1:500,000 – 1,000,000 5.
The mechanism of development of
ISH following spinal anesthesia is analogous to PDPH. It is postulated
that the orifice made in the dura mater after puncturing with the
cerebrospinal fluid (CSF) needle, remains open for several weeks after
the puncture. This leads to rapid loss of CSF which reduces the
intraspinal and intracranial pressure. This causes a caudal shift of the
brain, which causes traction of the structures sensitive to pain and
bridging veins in the subdural space leading to its rupture causing ISH
and headache 5,6. The time taken for diagnosis of ISH
following a dural puncture ranges from 4 h to 29 weeks2,4.
The time that is taken from CSF loss to progress to headache and develop
hematoma range from 2 hours to 44 days 5. Most often
when physicians come upon a case of headache following spinal
anesthesia, PDPH is assumed to be the cause 3,7.
Headache due to PDPH worsens or develops within 15 minutes after sitting
or standing up, and it improves within a similar period after laying
down. It appears within 5 days after the puncture and resolves
spontaneously within 1 week or up to 48 hours after epidural blood patch8,9. This distinguishing feature helps us to exclude
other causes of postpartum headache. However, in rare situations, the
headache may last for months or even years 10. ISH
should be suspected in a patient when PDPH changes its characteristics
to non-postural headache with possible accompanying features like focal
central nervous system (CNS) signs, impairment in consciousness level,
paresis, ptosis, vomiting, blurring of vision, drowsiness,
disorientation, prolonged unresolved headache 1,6.
Unlike these typical features, ISH may present only as a headache and
may be unrelated to PDPH 8.
Postpartum headaches are quite common (39%) 4,
majority of them are primary headaches such as (migraine, tension-type,
and cluster headache) and are therefore considered first in the
differential diagnosis 4. Secondary postpartum
headache can be fatal and includes PDPH, eclampsia/pre-eclampsia,
cerebral venous thrombosis, reversible cerebral vasoconstriction
syndrome, pituitary mass/hemorrhage 4. It is common
that these headaches coexist and simulate each other in the puerperium
causing difficulty in differentiation 8.
Predisposing factors for ISH following spinal anesthesia are pregnancy,
use of large-sized needles, multiple dural punctures dehydration, use of
anticoagulants, cerebral vascular abnormalities, and brain atrophy1,2,9. Increased susceptibility during pregnancy may
be due to differences in elasticity of the dura, hemostatic imbalance,
and possibly gender-based differences in cranial morphology1. Due to venous dilatation in pregnancy intracranial
vessels are prone to tear and bleed. Moreover, postpartum diuresis,
peripartum dehydration which could decrease the amount of CSF, sudden
reduction of intra-abdominal pressure, vena caval pressure at delivery,
hormonally-induced ligamentous changes 3, Valsalva
maneuver at labor 3,9, thrombocytopenia3,9 increases the susceptibility to develop cerebral
SDH.
Diagnosis of ISH is usually made by a CT scan of the head. However,
cranial Magnetic resonance imaging is more sensitive and specific for
iso-dense CSDH 7. Surgery is indicated if the
thickness of hematoma is more than 10 mm, midline shift is greater than
5 mm, or there is neurologic deterioration 4. In
absence of the above features, conservative management is recommended
which requires close neurological and radiological follow ups1,2. In addition, it is established that ISH caused by
dural punctures resulting in long-standing CSF leakage can also be
treated with epidural dural patching 4.
The incidence of ISH following spinal anesthesia and development of
related complications is preventable to some extent, vigilance regarding
procedure-related factors, prophylactic monitoring of susceptible
patients, and regular follow-up after discharge help in avoiding
potential morbidity and mortality6.
In the reported case the patient developed headache 13 days after LSCS.
Her headache did not have an association with PDPH and other neurologic
signs. As her symptoms were vague, there was a possibility of
misdiagnosis. Perhaps, the development of CSDH in her case was chiefly
due to the lumbar puncture during spinal anesthesia. Moreover, her
post-pregnancy status may have added up as a predisposing factor for the
progression of the CSDH.