Intracranial hypotension due to shunt overdrainage presenting as reversible dorsal midbrain syndrome

Intracranial hypotension syndrome is an uncommon manifestation of shunt overdrainage; characterized by a triad of postural headache, diffuse pachymeningeal gadolinium enhancement and low cerebrospinal fluid opening pressure. We describe a young female with recurrent episodes of postural headaches and reversible dorsal midbrain syndrome due to intracranial hypotension as a complication of shunt overdrainage, and a subsequent improvement following shunt ligation. Neurology Asia 2014; 19(1) : 107 – 110 Address correspondence to: Dr. Meena Gupta, DM (Neurology), Director, Professor, Department of Neurology, 5th Floor, Academic Block, G.B. Pant Hospital, JLN Marg, New Delhi -110002 (India). Tel: 09718599301, 011232324242 ext.5501, 01123231298; Email: [email protected] INTRODUCTION Dorsal midbrain syndrome was first described by Parinaud H in 1883. Since then this syndrome has been also designated as Parinaud’s syndrome, Sylvian aqueduct syndrome, Pretectal syndrome, and Koerber-Salus-Elschnig syndrome.2 It is characterized by conjugate paralysis of upward gaze (occasionally down-gaze), abnormal pupillary reaction (large pupils with light-near dissociation), pathologic retraction of upper lid (Collier’s sign), and convergence-retraction nystagmus on upward gaze. The syndrome reflects damage to pathway involving vertical gaze; i.e., rostral interstitial nucleus of the medial longitudinal fasciculus, the interstitial nucleus of Cajal, the posterior commissure, and the nucleus of the posterior commissure. Stroke and tumors are the common causes of dorsal midbrain syndrome.2,3 Less common causes include hypoxia, trauma, multiple sclerosis, tuberculosis, neurocysticercosis, syphilis, sarcoidosis, Wilson’s disease, Whipple’s disease, lipid storage diseases, and certain drugs (barbiturates, carbamazepine, and neuroleptics). Dorsal midbrain syndrome has been described in obstructive hydrocephalus patients with shunt malfunction and rarely in patients with spontaneous intracranial hypotension. We describe a young female with recurrent episodes of postural headaches and reversible dorsal midbrain syndrome due to intracranial hypotension as a complication of shunt overdrainage, and a subsequent improvement following shunt ligation. CASE REPORT A 24 year old female presented with two year history of recurrent episodes of headaches associated with vomitings, excessive sleepiness, double vision, drooping of eyelids, with downward and inward deviation of eyes. There was no history of fever, loss of appetite or weight. The episodes were occurring 2-3 times per month, and most were precipitated by dehydration. All the episodes were reversible with hydration and antiemetics. Since last six months she also developed slowness in her activities of daily living, but there was no tremulousness, abnormal posturing, or falls. She had history of tubercular meningitis with communicating hydrocephalus for which she underwent ventriculoperitoneal (VP) shunting ten years back. Two of her episodes were observed during her hospital stay. Her general physical and systemic examination was unremarkable. On neurological examination during the episodes she was conscious, oriented; had bilateral complete ptosis, downward and inwards deviated eyes, impaired vertical and horizontal gaze, with middilated reacting pupils (Figure 1a,b). Rest of the cranial nerves including fundus examination was normal and there were no signs of meningeal irritation. Motor system examination revealed mild axial and limb rigidity, bradykinesia, generalized hyperreflexia and mild postural instability, without any limb weakness. Sensory system and cerebellar examination was normal. A clinical diagnosis of dorsal midbrain syndrome with parkinsonism (probably drug induced) was considered. Neurology Asia March 2014 108 Her routine hematological and biochemical investigations, x-ray chest and abdominal ultrasound all were normal. Magnetic resonance imaging (MRI) brain revealed normal brain parenchyma, slit ventricles, flattening of the midbrain and pons, and mild diffuse pachymeningeal enhancement (Figure 2a,b,c,d). Lumbar puncture and intracranial pressure monitoring was not done because of risk of clinical worsening. With hydration and antiemetics her eye deviation and postural instability improved within 4-5 days; however her upgaze limitation and mild parkinsonian symptoms persisted (Figure 3a,b). In view of clinical and MRI findings a possibility of VP shunt overdrainage as a cause of intracranial hypotension leading to postural headaches and reversible dorsal midbrain syndrome was considered and she underwent ligation of shunt to reduce overdrainage. For Parkinsonian symptoms she was started on tab Syndopa 125 mg four times a day. On follow up after one year she showed significant improvement with only four such episodes. All the episodes were less severe, not requiring hospitalization and all remitted within 2-3 days with hydration. Her Parkinsonian symptoms were also improved and she resume back to her work. Follow up MRI brain at one year revealed mild communicating hydrocephalus with hemosiderin deposits in lentiform nuclei bilaterally (Figure 4a,b). Figure 1 a,b. During the episode, bilateral complete ptosis; eyes deviated downward and inwards with impaired vertical and horizontal gaze. Figure 2 a,b,c,d. MRI brain (T2 axial and sagittal; T1 contrast axial and sagittal images) showing slit ventricles, flattening of the midbrain and pons, and mild diffuse pachymeningeal enhancement. Figure 3 a,b. After recovery persistent upgaze limitation. Figure 4 a,b. Follow up MRI brain (T1 and T2 axial images) showing mild communicating hydrocephalus with hemosiderin deposits in bilateral lentiform nucleus.