Intracranial hypertension causing polyradiculopathy and late or absent F‐waves

Intracranial hypertension is well known to cause cranial neuropathies. The syndrome of intracranial hypertension causing limb weakness and paraesthesias is not, however, well described.¹,²,³,⁴ An illustrative case of intracranial hypertension causing polyradiculopathy with late or absent F‐waves is presented and compared with cases previously reported in the literature.

Case report

A 20‐year‐old previously healthy woman presented with 1 month of intermittent nausea, vomiting, headaches and blurred vision, 1–2 weeks of weakness and paraesthesia in the arms and legs, and pain in the right side of the neck. She was taking no drugs.

Neurological examination showed swollen optic discs. She had bilateral abducens palsies. Shoulder abduction, finger abduction, finger extension and hip flexion were weak bilaterally (Medical Research Council grade 4/5). Muscle stretch reflexes were diffusely absent. Sensation was intact to all modalities. Her gait was slightly unsteady.

Computed tomogram, magnetic resonance angiogram, magnetic resonance venogram and magnetic resonance image of the brain with contrast, and magnetic resonance image of the cervical and lumbar spine with contrast were normal. The following laboratory studies were unremarkable: pregnancy test, electrolytes, complete blood count, liver enzymes, urine analysis, prothrombin time or partial thromboplastin time, antinuclear antibodes and HIV. Erythrocyte sedimentation rate was increased at 60. Lumbar puncture showed an opening pressure of 550 mm H₂O. Analysis of the cerebrospinal fluid (CSF) showed one white cell and one red blood cell, glucose concentration of 78 mg/dl, protein concentration of 26 mg/dl and Gram stain with rare white cells and no organisms.

Visual acuity was OD (L. oculus dexter) 20/50 and OS (L. oculus sinister) 20/40‐2 with pinhole. Visual field examination showed mild concentric contraction of isopters for either eye and enlargement of the blind spots.

Nerve conduction studies (NCS) were normal except for absent F‐waves in the median, peroneal and tibial nerves and a prolonged minimum F‐wave latency in the ulnar nerve (76.5 ms). The right median, ulnar and sural sensory conductions were normal. Electromyography of the right abductor pollicis brevis, first dorsal interosseous, tibialis anterior, gastrocnemius and iliopsoas showed no abnormal spontaneous activity and normal motor unit action potentials. A neurogenic recruitment pattern was present in the abductor pollicis brevis muscle.

The patient's vision and weakness worsened despite treatment with intravenous immunoglobulin for the presumed diagnosis of Guillain–Barré syndrome (GBS). Repeat ophthalmological examination showed loss of nasal field in the left eye. Repeat lumbar puncture (5 weeks after the onset of symptoms) showed an opening pressure of >550 mm H₂O with a protein concentration of 21 mg/dl in the CSF. NCS continued to show prolonged or absent F‐waves without other demyelinating features. The patient was started on prednisone and acetazolamide and an external ventricular drain was placed. During the first 24 h after external ventricular drain placement, intracranial pressure was greater than 400 mm H₂O. The patient's nausea, headache and neck pain resolved. Visual blurring and distal paraesthesias improved over several days. Intracranial pressure dropped to <200 mm H₂O, and a ventriculoperitoneal shunt was placed. Over the next 24 h, muscle stretch reflexes returned in the lower extremities and hip flexor strength improved. NCS showed return of normal F‐wave responses. Prednisone and diuretic treatment were discontinued.

A follow‐up clinic visit 2 weeks later found that the patient had improved. Her examination showed only a mild right abducens palsy and minimal hand weakness. She continued to have bilateral papilloedema. Telephone follow‐up 1 and 4 months later showed that she was asymptomatic.

Literature review

The authors reviewed the literature (Pub Med) for case reports meeting the following criteria: (1) papilloedema, (2) increased opening pressure on lumbar puncture (>250 mm H₂O), (3) normal (<45 mg/dl) or slightly increased (45–75 mg/dl) protein concentration in the CSF and (4) areflexia or hyporeflexia.

Including our case, 13 cases met these criteria, 10 with benign intracranial hypertension and 3 with cerebral venous sinus thrombosis (table 1).¹,²,³,⁴,⁵,⁶,⁷,⁸,⁹ A total of nine patients were reported to have limb weakness, two with tetraplegia. Radicular pain or paraesthesias were described in nine patients. Cases of abducens palsy (n = 7), bilateral global ophthalmoplegia (n = 4) and facial weakness (n = 7) were reported. Headache and visual loss were common, absent in only three patients.

Table 1 Cases (n = 13) meeting the authors' four criteria.

Patient no (ref)	Age/sex	Clinical presentation (in addition to papilloedema)	LP opening pressure (mm H2O)	LP protein (mg/dl)	Imaging	EDX	Treatment	Outcome
1 (Kincaid 2006)	20/F	HA, CN 6 palsy, paraesthesias, radicular pain, limb weakness and areflexia	1–550	1–26	MRI/MRA/MRV brain—normal	F‐waves absent (M, P, T) or delayed (U)	1—Steroids, IVIG	After EVD: radicular pain relief, return of reflexes and strength
			2–550	2–21			2—Diamox, EVD
							3—VPS
2 (Moosa 2004)	24/F	Vision loss, ophthalmoplegia, limb weakness, areflexia, Kerning's sign	>400	40	Digital subtraction angiography —sinus venous thrombosis	Normal, including F‐waves	LPS	Improved over 2 weeks
3 (Moosa 2004)	33/F	Neck/back pain, vision loss, NR pupils, ophthalmoplegia, CN 7 palsy, limb weakness, areflexia	>850	44	MRI/MRV	F‐waves absent in all extremities (after LPS: return of F‐waves)	LPS	Recovery of CN function and partial return of strength
					Sinus venous thrombosis with haemorrhagic infarct
4 (Kharbanda 2002)	35/F	CN 6 and 7 palsy, limb weakness and areflexia	420	20	CT and MRI brain—normal	F‐waves absent	Steroids, diuretics	Gradual recovery but permanent vision loss
5 (Obeid 2000)	24/F	Neck/shoulder pain, CN 6 and 7 palsy, limb weakness and areflexia	420	40	MRI brain and cervical spine—normal	F‐waves prolonged (M, U)	1—Steroids	Improvement with LPS
							2—IVIG
							3—Repeat LPs, diuretics
							4—LPS
6 (Obeid 2000)	28/F	L shoulder pain, CN 6 and 7 palsy, limb weakness and areflexia	1–400	1—Normal	MRI/MRA brain—sinus venous thrombosis	F‐waves prolonged, decreased amplitude CMAP and SNAP	1—Steroids, diuretics, anticoagulation	Improvement with LPS
			2–570	2–73			2—IVIG
							3—LPS
7 (Weiss 1991)	22/F	Radiating neck pain, paraesthesias, CN 6 and 7 palsy, limb weakness, areflexia	1–600	1–14	CT brain—normal	F‐waves absent or prolonged	Repeat LPS and diuretics	Return of strength, but persistent areflexia and papilloedema with changes in visual field
			2–110	2–57
			3–350	3–62
8 (Kidron 1989)	18/F	Generalised seizure, bilateral vision loss, ophthalmoplegia, neck stiffness, areflexia	1–600	1–20	CT and MRI brain, cerebral angiogram—normal	ND	1—Steroids, diuretics, EVD	Improvement with EVD; when EVD d/c'd facial diplegia developed; definitive tx with LPS
			2–330	2—Normal			2—LPS
9 (Kidron 1989)	26/F	Blindness, bilateral opthalmoparesis, bilateral LE areflexia	>600	60	CT brain, cerebral angiogram—normal	ND	1—Steroids, diuretics	Further CN deficits after 3 days of conservative management
							2—EVD	Clinical improvement after EVD
10 (Macaya 1988)	5/F	Neck/back pain with radiation to L arm, hyporeflexia, CN 6 and 7 palsy	1–480	1–16	CT brain—normal	Impersistent F‐waves (M, P, T) normalised after repeat LPs	Repeat LPS	Improved radicular pain after LP, resolution of papilloedema
			2–510	2–23
11 (Murray 1986)	4/F	L neck/shoulder pain, L arm areflexia	1–550	1–16	CT brain, cervical myelogram, bone scan—normal	ND	1—Repeated LPS	Pain resolved after repeated LP, asymptomatic with normal examination at 5 months
			2–550	2 and 3—Normal			2—Steroids, diuretics
			3–350
12 (Bortoluzzi 1982)	34/F	Back/leg pain, numbness T6–T12, LE weakness, global hyporeflexia	350–450 (Multiple)	Normal	CT brain, spine—normal, cisternography—enlarged SA space below L2	ND	1—Steroids, diuretics	Improved pain after LPS, normal examination at 7 months
							2—LPS
13 (Sullivan 1977)	24/F	CN 6 and 7 palsies, limb weakness, unilateral hyporeflexia	1–310	1–15	CT brain, cerebral angiogram, normal	F‐waves—ND	Steroids	Gradual resolution of papilloedema and facial palsy
			2–245	2–23

CMAP, compound muscle action potential; CN, cranial nerve; CT, computed tomography; d/c'd, discontinued; EDX, electrodiagnostic testing; EVD, external ventricular drain; HA, headache; IVIG, intravenous immunoglobulin; L, left; LE, lower extremity; LP, lumbar puncture; LPS, lumboperitoneal shunt; mm H₂O, millimetres water; M, median nerve; MRA, magnetic resonance angiogram; MRI, magnetic resonance imaging; MRV, magnetic resonance venogram; ND, not done; NR, non‐reactive; P, peroneal nerve; R, right; SA, subarachnoid; SNAP, sensory nerve action potential; T, tibial nerve; tx, treatment; U, ulnar nerve; VPS, ventriculoperitoneal shunt.

Placement of a CSF shunt led to clinical improvement characterised by return of strength, reflexes, F‐waves or elimination of radicular pain in all eight patients.

In the five patients who did not undergo continuous CSF drainage, three showed clinical improvement (patients 10, 11 and 13), but two showed persistent visual loss (patients 4 and 7).

Discussion

We propose that intracranial hypertension can cause a syndrome of weakness and areflexia in addition to the more classic signs of intracranial hypertension. Our patient and seven other patients reported absent or prolonged F‐waves on NCS in the absence of other demyelinating features. This finding is often considered to be an early electrodiagnostic finding in GBS. Follow‐up NCS were carried out in our patient and in two patients (patients 3 and 10), none of whom developed other electrophysiological evidence of demyelination and all showed return of normal F‐wave latencies after definitive treatment of intracranial hypertension. The return of normal F‐waves after CSF shunting or repeated lumbar puncture is supportive of a cause and effect relationship between intracranial hypertension and polyradiculopathy. On follow‐up, protein concentrations in the CSF continued to be normal or slightly increased in all cases reporting follow‐up CSF results (mean 39.2 mg/dl, range 21–73), again arguing against the theory that these cases represent GBS with papilloedema.

Patient 12 initially underwent back surgery for persistent radicular pain. During surgery, the authors noted the presence of “enlarged” nerve roots and lumbar dural sac. A cisternogram also documented enlargement of the subarachnoid spaces below L‐2 and of the thoracic root pouches bilaterally.⁷ The mechanism by which intracranial hypertension causes weakness and areflexia is unknown, but this finding would argue in favour of the theory that increased pressure in the subarachnoid spaces, with subsequent compression of the nerve roots, is the cause of the polyradiculopathy.

In conclusion, we propose that in particularly severe cases of intracranial hypertension, an under‐recognised syndrome of polyradiculopathy with absent or prolonged F‐waves may result. CSF shunting may lead to a better outcome than medical management in these patients, particularly with regard to preservation of vision. Therefore, timely recognition of this syndrome is necessary.