Answer for BIR CoW 24 Oct 2021
IDIOPATHIC INTRACRANIAL HYPOTENSION
Findings
T2 / FLAIR hyper intensity noted in Bilateral subdural regions overlying both cerebral hemispheres No evidence mass effect / midline shift noted. On contrast administration ,enhancement noted in bilateral thin subdural effusion. Enhancing Bilateral Pachymeningeal thickening noted around bilateral cerebral and tentorium cerebelli region .
Discussion
Intracranial hypotension (IH) is a benign, self-limiting condition caused by low cerebrospinal fluid (CSF) pressure, usually due to CSF leakage. The dominant clinical finding is an orthostatic headache. Other common clinical features include fever, nausea, vomiting, and tinnitus. Intracranial hypotension is of either primary (spontaneous intracranial hypotension – SIH) or secondary origin e.g. iatrogenic or traumatic. Spontaneous intracranial hypotension is believed to occur as a result of trivial trauma and weakness in the dural sac due to spontaneous dural dehiscence and dural tears caused by degenerative causes. There is also an association with connective tissue disorders such as Marfan and Ehlers-Danlos syndromes . Secondary intracranial hypotension may be caused by injury of the dura mater, e.g. following cranial or spinal surgery, lumbar puncture, spinal anaesthesia, placement of ventriculo-peritoneal shunts, and craniospinal trauma . PATHOLOGY : The typical abnormalities that are found in IH can be explained by the Monro-Kellie hypothesis, which states that the sum of volumes of the brain tissue, CSF, and intracranial blood is constant in an intact cranium . Therefore, low CSF pressure can be compensated for by an increase in the intracranial blood volume through enlargement of dural arteries or dilatation of cortical and medullary veins and dural venous sinuses , including the inferior inter cavernous sinus . This causes non-nodular enhancement of pachymeninges and sometimes also of dura mater of the spinal cord without leptomeningeal involvement. When compensatory dilatation of blood vessels is insufficient, contrast enhancement of pachymeninges may not occur . Unless enlargement of vessels is sufficient to maintain balance of the intracranial volume, subdural effusions may appear, and they occur most commonly in the fronto-parietal region, are bilateral, crescentic, thin, and do not cause a mass effect. They arise due to CSF extravasation through permeable microvessels of the dura mater To confirm the diagnosis of IH, at least 1 of the following signs must be present low CSF pressure, evidence of CSF leakage (on CT myelography, conventional myelography or radionuclide cisternography) or diffuse pachymeningeal enhancement on brain MRI imaging . Magnetic resonance imaging in patients with IH reveals brain and spinal abnormalities caused by low CSF pressure. The main MRI finding is a characteristic diffuse pachymeningeal enhancement. MRI may also show sagging of the brain Pituitary enlargement Subdural fluid collections (usually hygromas, less commonly haematomas) , posterior lobe pituitary haematomas Diffuse dural enhancement of the spinal canal, spinal epidural fluid collection , distension of the spinal epidural venous plexus, and abnormal intensity around the root sleeves .
REFERENCES : 1. Schaltenbrand G. Normal and pathological physiology of the cerebrospinal fluid circulation. Lancet. 2. Forghani R, Farb RI. Diagnosis and temporal evolution of signs of intracranial hypotension on MRI of the brain. Neuroradiology. 3. Schievink WI, Nuno M, Rozen TD, et al. Hyperprolactinemia due to spontaneous intracranial hypotension. 4. Sainani NI, Lawande MA, Pungavkar SA, et al. Spontaneous intracranial hypotension: A study of six cases with MR findings and literature review.
Findings
T2 / FLAIR hyper intensity noted in Bilateral subdural regions overlying both cerebral hemispheres No evidence mass effect / midline shift noted. On contrast administration ,enhancement noted in bilateral thin subdural effusion. Enhancing Bilateral Pachymeningeal thickening noted around bilateral cerebral and tentorium cerebelli region .
Discussion
Intracranial hypotension (IH) is a benign, self-limiting condition caused by low cerebrospinal fluid (CSF) pressure, usually due to CSF leakage. The dominant clinical finding is an orthostatic headache. Other common clinical features include fever, nausea, vomiting, and tinnitus. Intracranial hypotension is of either primary (spontaneous intracranial hypotension – SIH) or secondary origin e.g. iatrogenic or traumatic. Spontaneous intracranial hypotension is believed to occur as a result of trivial trauma and weakness in the dural sac due to spontaneous dural dehiscence and dural tears caused by degenerative causes. There is also an association with connective tissue disorders such as Marfan and Ehlers-Danlos syndromes . Secondary intracranial hypotension may be caused by injury of the dura mater, e.g. following cranial or spinal surgery, lumbar puncture, spinal anaesthesia, placement of ventriculo-peritoneal shunts, and craniospinal trauma . PATHOLOGY : The typical abnormalities that are found in IH can be explained by the Monro-Kellie hypothesis, which states that the sum of volumes of the brain tissue, CSF, and intracranial blood is constant in an intact cranium . Therefore, low CSF pressure can be compensated for by an increase in the intracranial blood volume through enlargement of dural arteries or dilatation of cortical and medullary veins and dural venous sinuses , including the inferior inter cavernous sinus . This causes non-nodular enhancement of pachymeninges and sometimes also of dura mater of the spinal cord without leptomeningeal involvement. When compensatory dilatation of blood vessels is insufficient, contrast enhancement of pachymeninges may not occur . Unless enlargement of vessels is sufficient to maintain balance of the intracranial volume, subdural effusions may appear, and they occur most commonly in the fronto-parietal region, are bilateral, crescentic, thin, and do not cause a mass effect. They arise due to CSF extravasation through permeable microvessels of the dura mater To confirm the diagnosis of IH, at least 1 of the following signs must be present low CSF pressure, evidence of CSF leakage (on CT myelography, conventional myelography or radionuclide cisternography) or diffuse pachymeningeal enhancement on brain MRI imaging . Magnetic resonance imaging in patients with IH reveals brain and spinal abnormalities caused by low CSF pressure. The main MRI finding is a characteristic diffuse pachymeningeal enhancement. MRI may also show sagging of the brain Pituitary enlargement Subdural fluid collections (usually hygromas, less commonly haematomas) , posterior lobe pituitary haematomas Diffuse dural enhancement of the spinal canal, spinal epidural fluid collection , distension of the spinal epidural venous plexus, and abnormal intensity around the root sleeves .
REFERENCES : 1. Schaltenbrand G. Normal and pathological physiology of the cerebrospinal fluid circulation. Lancet. 2. Forghani R, Farb RI. Diagnosis and temporal evolution of signs of intracranial hypotension on MRI of the brain. Neuroradiology. 3. Schievink WI, Nuno M, Rozen TD, et al. Hyperprolactinemia due to spontaneous intracranial hypotension. 4. Sainani NI, Lawande MA, Pungavkar SA, et al. Spontaneous intracranial hypotension: A study of six cases with MR findings and literature review.
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!