Diagnostic validity of somatosensory evoked potentials in subgroups of patients with sciatica.

The diagnostic utility of scalp-recorded somatosensory evoked potentials (SEP) in patients with sciatica has generally been regarded as low. The purpose of the present study was to determine the validity of sensory nerve SEP in different subgroups of sciatic patients. A total of 65 consecutive patients with sciatica showing disc pathology and/or facet joint hypertrophy on lumbar computed tomography (CT) and/or myelography were studied. Symptomatic myelographically compressed nerve roots were defined as truly compromised roots. Asymptomatic myelographically normal nerve roots were defined as truly normal roots. Bilateral sensory nerve SEP representing nerve roots L4, L5, and S1 were performed in all patients. Evaluation of SEP included the use of P1 latency inter-root comparison. The false-positive rate of SEP was low. Pathological L4, L5, and S1 SEP therefore strongly indicate true compromise of the corresponding nerve roots. The true-positive rate was higher in patients with facet joint hypertrophy with or without additional disc disease than in patients with disc pathology only, and highest if the sciatic sensory symptoms were present during the SEP registration. Diagnostic validity was not influenced by previous episodes of sciatica, the duration of the present episode, or the number of spinal levels with ipsilateral myelographically compressed nerve roots. Pathological SEP strongly indicate sensory radiculopathy in patients with sciatica. Diagnostic efficacy is higher in patients with facet joint hypertrophy than in patients with disc pathology only and highest when the sciatic symptoms are present during registration.

Cranial nerve clock. Part 1. A declarative memory paradigm.

RATIONALE AND OBJECTIVES: The authors performed this study to compare a declarative memory paradigm developed to help teach medical students about the cranial nerves with a traditional text-based approach. MATERIALS AND METHODS: The authors designed a clock-based paradigm to help medical students learn about the cranial nerves. To enhance memorization and related brain activation, the paradigm uses visual, spatial, and word associations in the context of an analog clock face. Twenty-one undergraduate students were randomly divided into two groups. Group T viewed traditional text slides, and group C viewed text slides followed by the corresponding cranial clock slides. Subjects were tested before and after these sessions. RESULTS: Group C performed significantly better than group T in learning the names of the cranial nerves and their correct order (P < .011). Recall of name, number, and function was better for 11 of 12 cranial nerves, with statistical significance reached for nerves III (P = .005), V (P = .04), and X (P = .03). CONCLUSION: Alternative teaching strategies may help improve declarative memory.

Cranial nerve clock. Part II: functional MR imaging of brain activation during a declarative memory task.

RATIONALE AND OBJECTIVES: The authors performed this study to assess brain activation during encoding and successful recall with a declarative memory paradigm that has previously been demonstrated to be effective for teaching students about the cranial nerves. MATERIALS AND METHODS: Twenty-four students underwent functional magnetic resonance (MR) imaging during encoding and recall of the name, number, and function of the 12 cranial nerves. The students viewed mnemonic graphic and text slides related to individual nerves, as well as their respective control slides. For the recall paradigm, students were prompted with the numbers 1-12 (test condition) intermixed with the number 14 (control condition). Subjects were tested about their knowledge of cranial nerves outside the MR unit before and after functional MR imaging. RESULTS: Students learned about the cranial nerves while undergoing functional MR imaging (mean post- vs preparadigm score, 8.1 +/- 3.4 [of a possible 12] vs 0.75 +/- 0.94, bilateral prefrontal cortex, left greater than right; P < 2.0 x 10(-12)) and maintained this knowledge at I week. The encoding and recall paradigms elicited distributed networks of brain activation. Encoding revealed statistically significant activation in the bilateral prefrontal cortex, left greater than right [corrected]; bilateral occipital and parietal associative cortices, parahippocampus region, fusiform gyri, and cerebellum. Successful recall activated the left much more than the right prefrontal, parietal associative, and anterior cingulate cortices; bilateral precuneus and cerebellum; and right more than the left posterior cingulate. CONCLUSION: A predictable pattern of brain activation at functional MR imaging accompanies the encoding and successful recall of the cranial nerves with this declarative memory paradigm.

Thrombus formation and structure and the evolution of mass effect in intracranial aneurysms treated by balloon embolization: emphasis on MR findings.

This study was designed to further assess the capabilities of MR as a tool for the diagnostic evaluation of patients with giant intracranial aneurysms, to determine MR's ability to define the degree of thrombosis present within giant aneurysms before and after treatment with balloon occlusion, and to delineate the MR characteristics of both spontaneous and induced thrombus within giant aneurysms. Nine patients with unclippable intracranial aneurysms treated by parent artery occlusion with detachable balloons were evaluated with MR, angiography, and CT. Pretreatment and posttreatment MR studies were evaluated for their ability to (1) define the size, configuration, and anatomic relationships of an aneurysm; (2) detect and characterize thrombus within an aneurysm; and (3) determine if treatment successfully caused complete aneurysm thrombosis. MR imaging does not replace angiography in either the pretreatment or the posttreatment evaluation of patients with giant intracranial aneurysms. Thrombus formation and dissolution is a complex, dynamic process. Active thrombus in incompletely thrombosed aneurysms differs from isolated organizing thrombus in completely thrombosed aneurysms. Induced and spontaneous thrombi differ in mechanisms of formation and in composition; their MR characteristics are also different. Reduction in mass effect is common after complete thrombosis of giant intracranial aneurysms.

Fat infiltration, atrophy and hypertrophy of skeletal muscles demonstrated by X-ray computed tomography in neurological patients.

Since 1982, we have used X-ray computed tomography (CT) to study the skeletal muscles of neurological patients. We present here the findings in 23 patients with myogenic and 29 patients with neurogenic diseases. The method is convenient to demonstrate fat infiltration, atrophy and hypertrophy of skeletal muscles, but is of little help in differentiating between the 2 disease categories or individual diagnoses. The maximal isometric voluntary force of m. quadriceps femoris was measured in 13 of the patients with neurogenic, and in 10 of the patients with myogenic diseases. The power was compared with the cross-sectional area and the structural changes observed in the parenchyme of the muscles in the CT scans. A positive correlation was found between the size and the force of the muscle in both patient groups. The appearance of the muscular parenchyme was of little help to predict its function.

Bone scintigraphy in the diagnosis of fracture and infection of the temporal bone.

The sensitivity of 99mTc-MDP-bone-scintigraphy in the diagnosis of temporal bone fracture was found equal to that of conventional radiography if the patients were examined 10 days after the trauma. Temporal bone osteomyelitis with concomitant moderate osteosclerosis was demonstrated by bone scintigraphy in 5 cases of mastoiditis with atypical symptoms. A case of apicitis was for the first time demonstrated by scintigraphy. A low sensitivity of 67Ga-scintigraphy was demonstrated by positive 99mTc-bone-scintigraphy and negative 67Ga-scintigraphy in a patient with atypical mastoiditis. 99mTc-scintigraphy was negative in 5 cases of otitis media suppurativa and in 3 cases of otitis media chronica cum cholesteatoma, all with slight degree of osteosclerosis in the mastoid. The sensitivity of 99mTc-bone-scintigraphy in fracture and osteomyelitis of the temporal bone seems to be a function of the amount of reactive new bone formed.

Severity of postmyelographic arachnoiditis and concentration of meglumine locarmate in primates.

Myelography with meglumine iocarmate, a dilute meglumine iocarmate solution, or gas was performed in macaque monkeys. Twelve weeks later the animals were examined myelographically and histologically for evidence of arachnoiditis. Arachnoiditis in the animals treated with dilute meglumine iocarmate and gas was significantly less than in those treated with meglumine iocarmate.

Intracranial arteriovenous malformations: conservative or surgical treatment?

Of 89 patients with arteriovenous malformations of the brain, 47 were conservatively treated, nine of these died (19%), four with the first bleed, five of recurrent bleeding. Of 42 surgically treated patients, five died, a mortality of 12%. Four of these deaths occurred with patients in a deteriorating clinical condition caused by large intracerebral haematomas. The fifth death occurred with a recurrent bleeding where a ligation of feeding artery was the only treatment. There were no deaths in those patients in good clinical condition who underwent an excision of the malformation. Total excision of arteriovenous malformations should be performed whenever possible.

Lumbar myelography.

The total material of lumbar myelographies performed with metrizamide (Amipaque) up to November 1976 (48,000 examinations) has been reviewed to assess the incidence of side-effects. A detailed analysis of 2,457 examinations from Ullevål Sykehus has been performed in order to assess adverse effects and diagnostic reliability. Three epileptic seizures were recorded, two of these in known epileptics. The rate of minor side-effects was low and the diagnostic accuracy high.